Issuu

Geological Society of Australia

ABSTRACTS Number

Palaeontology Down Under 2000 Kinross Wolaroi, Orange, NSW 11-15 July 2000 Australian Palaeontological Convention (including the Barry Webby Symposium) Third International Symposium on the Silurian System (Sir Frederick McCoy Symposium) Second Australasian Conodont Symposium IGCP410 IGCP 421

Macquarie University Centre for Ecostratigraphy & Paiaeobioiogy

PALAEONTOLOGY DOWN-UNDER 2000 11TH-15TH JULY 2000 ORANGE, NSW, AUSTRALIA

ABSTRACTS

c m International Palaeontological Association

Under the auspices of the International Palaeontological the Association of Australasian the Macquarie University Centre for Association of Australasian Palaeontologists

and

Association, Palaeontologists, Ecostratigraphy

Paiaeobioiogy

and IGCP Projects 410 and 421.

Geological Society of Australia, Abstracts Number 61 Palaeontology Down-Under 2000 11-15 July, 2000 held at Kinross Wolaroi School, Orange, N.S.W., Australia

Editors: Peter Cockle, George A. Wilson, Glenn A. Brock, Michael J. Engelbretsen, Andrew Simpson, Theresa Winchester-Seeto.

ISSN 0729 01IX © Geological Society of Australia Incorporated, 2000

Preferred citation for papers in this volume: Adhamian, A. & Ghobadi pour, M. 2000. Heliopyge sp. nov. (Asteropyginae: Trilobita) from the Soh area, central Iran. Palaeontology Down Under 2000, Geological Society of Australia, Abstracts 61, 10. Material published here may be freely copied for library, educational or research purposes, but replication of any part requires written permission from the Geological Society of Australia, as well as appropriate acknowledgement. Copies of this publication may be obtainedfrom: Geological Society of Australia Incorporated Suite 706, 301 George Street Sydney NSW 2000 Australia Price: AUD20.00

TAXONOMIC/NOMENCLATURAL DISCLAIMER This publication is not deemed valid for taxonomic or nomenclatural purposes (See ICZN, 4th edition, 1999)

Printed by: Conference Publications, Springwood, NSW

Palaeontology Down Under

Contents

TABLE OF CONTENTS SECTION I Papers ADHAMIAN, A. AND GHOBADI POUR, M. THE HELIOPYGE SP. NOV. (ASTEROPYGINAE: TRILOBITES) FROM THE SOH AREA, CENTRAL IRAN

BRETT, C.E. AND RAY, D.C. SEQUENCE AND EVENT STRATIGRAPHY OF THE MEDIAL SILURIAN OF EASTERN NORTH AMERICA: COMPARISON OF NEW YORK AND SOUTHERN OHIONORTHERN KENTUCKY

BRIGGS, D.E.G., ORR, P.J., SIVETER, DAVID J., SIVETER, DEREK J. AND SUTTON, M.D. THE PRESERVATION AND RECONSTRUCTION OF FOSSILS FROM THE HEREFORDSHIRE (SILURIAN) LAGERSTATTE

BROCK, G.A. AND PERCIVAL, I.G. CAMBRIAN FAUNAS FROM MOUNT ARROWSMITH, NORTH-WESTERN NEW SOUTH WALES, AUSTRALIA

BROWNLAW, R.L.S. AND JELL, J.S. PALAEOECOLOGY AND DISTRIBUTION OF SHALLOW-WATER RUGOSE CORALS IN THE MIDDLE AND UPPER DEVONIAN REEF COMPLEXES, CANNING BASIN, WESTERN AUSTRALIA

BURYI, G.I. AND KASATKINA, A.P. DISCOVERY OF EUCONODONTS NEW SKELETAL ELEMENT

CHEN XU, FAN JUN-XUAN, AND MITCHELL, C.E. HIRNANTIAN GRAPTOLITE DIVERSITY CHANGES FROM THE YANGTZE REGION

CHEN XU, ZHOU ZHI-YI, RONG JIA-YU AND LI JUN ORDOVICIAN SERIES AND STAGES IN CHINESE STRATIGRAPHY: STEPS TOWARD A GLOBAL USAGE

CHOI, D.K., KIM, D.H. AND SOHN, J.W. ORDOVICIAN TRILOBITE FAUNAS AND DEPOSITIONAL HISTORY OF THE TAEBAEKSAN BASIN, KOREA: IMPLICATION TO PALAEOGEOGRAPHY

CONAGHAN, P.J. AND BISCHOFF, G.C.O. HONEYCOMBE-TEMPLATE-PATTERN-LIKE MINERAL-OCCLUSION PROBLEMATICA OF CLOSED OSTRACOD CARAPACES IN LOWER SILURIAN LIMESTONES OF MIDWESTERN NEW SOUTH WALES EXPLAINED AS FOSSILISED TRAPPED TAPHONOMIC GAS-BUBBLE COMPLEXES THAT FORMED DIAGENETICALLY AT SHALLOW BURIAL DEPTHS

CORRADINI, C., BARCA, S. AND SPALLETTA, C. LATE DEVONIAN - EARLY CARBONIFEROUS CONODONTS FROM SE SARDINIA (ITALY)

DANIELL, J. J. SEDIMENTOLOGY AND BIOSTRATIGRAPHY OF A MID-DEVONIAN CARBONATE PLATFORM MARGIN, BROKEN RIVER PROVINCE, NORTH QUEENSLAND

Contents

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DASTANPOUR, M. PALAEOECOLOGY OF THE FRASNIAN SPINA TRYPINA FROM KERMAN, SOUTHEAST IRAN

DUBININA, S.V. AND RYAZANTSEV, A.V. DISTRIBUTION OF EARLY ORDOVICIAN-EARLY SILURIAN CONODONTS IN SILICEOUS BASALT COMPLEXES OF THE SOUTHERN URALS

ETHINGTON, R.L., NICOLL, R.S., NOWLAN, G.S AND REPETSKI, J.E. OEPIKODUS BIOGEOGRAPHY AND PALAEOECOLOGY IN THE ORDOVICIAN

30 EARLY

FAN, J., CHEN X. AND ZHANG, Y QUANTITATIVE BIOSTRATIGRAPHIC STUDY OF YANGTZE PLATFORM WITH THE DESIGNING OF SINOCOR 2.0, A SOFTWARE PROGRAM FOR GRAPHIC CORRELATION

FARRELL, J.R. LATE PRIDOLI, LOCHKOVIAN AND EARLY PRAGIAN CONODONTS FROM THE GAP AREA BETWEEN LARRAS LEE AND EURIMBLA, CENTRAL EASTERN NSW

FERRETTI, A. AND SCH6NLAUB, H.P. HIRNANTIAN CONODONTS FROM THE CARNIC ALPS, AUSTRIA

FRANKE, W. THE SUTURE ZONE BETWEEN AVALONIA AND THE ARMORICAN TERRANE ASSEMBLAGE IN CENTRAL EUROPE

FRANKE, W., DOUBLIER, M., K0NIGSHOF, P. AND WIEDERER, U. IN LOVE WITH CONODONTS

GILI, E. AND SKELTON, P.W. FACTORS REGULATING THE DEVELOPMENT OF ELEVATOR RUDIST CONGREGATIONS IN A SANTONIAN CARBONATE PLATFORM SEQUENCE, SOUTHERN CENTRAL PYRENEES

GROVER, G. THE PALAEODEPTH AND TEMPERATURE INDICATORS OF TORQUAY, VICTORIA, FROM AHERMATYPIC CORALS

HAIRAPETIAN, V. AND YAZDI, M. LATE DEVONIAN CONODONTS FROM DALMEH SECTION, NORTHEASTERN ARDEKAN, CENTRAL IRAN

HAIRAPETIAN, V., YAZDI, M. AND LONG, J.A. DEVONIAN VERTEBRATE BIOSTRATIGRAPHY OF CENTRAL IRAN

HERAVI, M.A., YAZDI, M. AND KARIMI, L. PRELIMINARY ANALYSIS OF LATE DEVONIAN CONODONTS FROM KHUSHYEILAGH FORMATION (MIGHAN SECTION), EASTERN ALBORZ, IRAN

JOHANSON, Z. AND RITCHIE, A. SARCOPTERYGIAN FISHES FROM THE HUNTER SILTSTONE (LATE FAMENNIAN) NEAR GRENFELL, NSW, AUSTRALIA

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Contents

JOHNSON, M.E. AND RONG J-Y. SIGNIFICANCE OF A PALAEOISLAND AND RELATED ROCKY COASTLINE FROM THE UPPER SILURIAN (LUDLOW) OF THE SINO-KOREAN PLATE

JOWETT, D.M.S. AND BARNES, C.R LATEST ORDOVICIAN-EARLY SILURIAN CONODONT BIOSTRATIGRAPHY IN THE CAPE PHILLIPS FORMATION, ARCTIC CANADA

KEBRIA-EE, M.R. BIOSTRATIGRAPHY AND PALAEOECOLOGY OF SPINATRYPINA HORIZON IN CENTRAL IRAN (ESFAHAN AND KERMAN REGIONS)

KOZLOWSKA-DAWIDZIUK, A., POREBSKA, E. AND MASIAK, M. GEOCHEMISTRY, ACRITARCHS AND GRAPTOLITES OF THE LUNDGRENI EVENT OF THE EAST EUROPEAN PLATFORM

KRAFT, P. AND KRAFT, J. FAUNAL CHANGEOVER AND DIVERSITY TRENDS ON THE LLANVIRNIAN BOUNDARY IN THE BOHEMIAN ORDOVICIAN

51 ARENIGIAN-

LAURIE, J.R. THE AGSO PALAEONTOLOGICAL COLLECTIONS

LAURIE, J.R. MIDDLE CAMBRIAN BIOSTRATIGRAPHY OF THE SOUTHERN GEORGINA BASIN, NORTHERN TERRITORY: PRELIMINARY RESULTS

LENZ, A.C. AND KOZLOWSKA-DAWIDZIUK, A. THE UPPER WENLOCK GRAPTOLITE EXTINCTION (LUNDGRENI EXTINCTION EVENT): PERSPECTIVES FROM ARCTIC CANADA

MAREK, J., WEBER, B., SCHONIAN, F., EGENHOFF, S.O. AND ERDTMANN, B. ARENIG CEPHALOPODS FROM SOUTHERN BOLIVIA

MAWSON, R., MOLLOY, P.D., SIMPSON, A.J. AND TALENT, J.A. SILURO-DEVONIAN (PRIDOLI-LOCHKOVIAN) CONODONTS FROM THE NOWSHERA AREA, PAKISTAN: IMPLICATIONS FOR THE MID-PALAEOZOIC STRATIGRAPHY OF THE PESHAWAR BASIN

McCANN, D. FREDERICK McCOY: AUSTRALIA'S FIRST PALAEONTOLOGIST

McGOWRAN, B. AND QIANYU LI SEQUENCE BIOSTRATIGRAPHY AND FORAMIN-IFERA IN THE CAINOZOIC

61 EVOLUTIONARY

PALAEOECOLOGY:

MELCHIN, M.J. AND WILLIAMS, S.H. A RESTUDY OF THE AKIDOGRAPTINE GRAPTOLITES FROM DOB'S LINN AND A PROPOSED REDEFINED ZONATION OF THE SILURIAN STRATOTYPE

MELCHIN, M.J., HEATH, R.J., JOWETT, D.M.S., SENIOR, S.H., BARNES, C.R. AND MARSHALL, J.D. CORRELATION OF THE GRAPTOLITE AND CONODONT ZONATIONS AND CARBON ISOTOPE SIGNAL THROUGH THE LATE LLANDOVERY AND EARLY WENLOCK, CORNWALLIS ISLAND, ARCTIC CANADA

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Contents

METCALFE, I. COLOUR AND TEXTURAL ALTERATION OF PALAEOZOIC AND TRIASSIC CONODONTS FROM PENINSULAR MALAYSIA: IMPLICATIONS FOR TECTONIC EVOLUTION AND HYDROCARBON GENERATION

MINJIN, Ch. THE ORDOVICIAN AND SILURIAN ROCKS OF MONGOLIA

MULLINS, G.L. AND LOYDELL, D.K. INTEGRATED SILURIAN CHITINOZOAN AND GRAPTOLITE BIOSTRATIGRAPHY OF THE BANWY RIVER SECTION, WALES, UK

NARBONNE, G.M., GEHLING, J.G. AND DALRYMPLE, RW. THE MISTAKEN POINT ASSEMBLAGE (EDIACARIAN) OF FOUNDLAND: A NEW LOOK AT SOME OLD FOSSILS

71 EASTERN

NEW-

NICOLL, R.S. AND ETHINGTON, R.L. NEW SEPTIMEMBRATE CONODONT TAXA OF THE FAMILY OEPIKODONTIDAE FROM THE EARLY ORDOVICIAN OF AUSTRALIA AND NEVADA

NIPPERESS, D.A. PALAEOINFORMATICS: TOOLS FOR THE MANAGEMENT AND DISSEMINATION OF PALAEONTOLOGICAL INFORMATION.

PACKHAM, G.H., PERCIVAL, I.G., RICKARDS, RB. & WRIGHT, A.J. LATE SILURIAN AND EARLY DEVONIAN BIOSTRATIGRAPHY IN THE HILL END TROUGH AND THE LIMEKILNS AREA, NEW SOUTH WALES

PARIS, F. AND BOURAHROUH, A. THE ULTIMATE EFFECTS OF THE LATE NORTHERN GONDWANA CHITINOZOANS

75 ORDOVICIAN

GLACIATION

PERCIVAL, I.G., SHERWIN, L. AND PICKETT, J. BOLINDIAN (LATE ORDOVICIAN) BIOSTRATIGRAPHY OF CENTRAL NEW SOUTH WALES

PERRI, M.C. AND FARABEGOLI, E. CONODONTS ACROSS THE PERMO-TRIASSIC BOUNDARY IN THE SOUTHERN ALPS

PERRI, M.C., TALENT, J.A.T., AHMAD, I., ALI, A., MOLLOY, P.D. AND CONAGHAN, P.J. PREVALENCE OF TRIASSIC LIMESTONE SEQUENCES IN NORTHERN PAKISTAN

PICARRA, J.M. HIGH RESOLUTION GRAPTOLITE BIOSTRATIGRAPHY IN THE SILURIAN OF THE BARRANCOS REGION, SOUTH PORTUGAL

PICARRA, J.M., ROBARDET, M., PARIS, F., LARDEUX, H. AND GUTIERREZMARCO, J.C. FIRST EVIDENCE OF THE BASAL LLANDOVERY (PARAKIDOGRAPTUS ACUMINATUS GRAPTOLITE BIOZONE) IN THE ARMORICAN MASSIF (WESTERN FRANCE)

PICKETT, J. AND PERCIVAL, I.G. ORDOVICIAN FAUNAS AND BIOSTRATIGRAPHY IN THE GUNNINGBLAND AREA, CENTRAL NEW SOUTH WALES

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Contents

RONG, J.-Y., HARPER, D.A.T. AND ZHAN, R.-B. LATE ORDOVICIAN BRACHIOPOD MASS EXTINCTION RECOVERY IN SOUTH CHINA

91 AND

SUBSEQUENT

SANDFORD, A.C. SYSTEMATICS, BIOSTRATIGRAPHY AND PALAEOENVIRONMENTS OF A NEW GENUS OF PHACOPID TRILOBITE FROM THE LATE SILURIAN-EARLY DEVONIAN OF SOUTH EASTERN AUSTRALIA

SERPAGLI, E. AND HAMMANN, W. CYCLOCRINITES EICHWALD, 1840 (DASYCLADALES) FROM THE UPPER ORDOVICIAN PORTIXEDDU FORMATION OF SW-SARDINIA AND ITS BEARING ON PALAEO-GEOGRAPHY AND SYSTEMATICS

SERVAIS, T., FATKA, O., BROCKE, R., DORNING, K.J., HEUSE,T.» LE HERISSE, A., MOEYNEUX, S., RIBECAI, C., RUBINSTEIN, C.V., VANGUESTAINE, M., VECOLI, M. AND WICANDER, R. A COMPLETE CATALOGUE OF ORDOVICIAN ACRITARCH SPECIES

SIMPSON, A. LATE SILURIAN AUTOCHTHONOUS AND ALLOCHTHONOUS CARBONATES IN THE BROKEN RIVER REGION, NORTHEASTERN AUSTRALIA

SLOAN, T. RESULTS OF A NEW COMPUTER-BASED METHOD FOR THE DIFFERENTIATION OF CONODONT SPECIES

SNELL, J.F. PHYLOGENETIC RELATIONSHIPS OF WENLOCK FENESTRATE BRYOZOA

100

SOJA, C. M., WHITE, B. AND ANTOSHKINA, A.I. SILURIAN ISLANDS IN THE URALIAN SEAWAY

102

SUN W., ZANG W. AND ZHOU C. SEQUENCE STRATIGRAPHY, ACRITARCHS AND CORRELATION OF THE LATEST NEOPROTEROZOIC SEQUENCES BETWEEN CHINA AND AUSTRALIA

104

SZANIAWSKI, H. ORGANIC STRUCTURES OF PROTOCONODONT, PARACONODONT AND EARLY EUCONODONT ELEMENTS

105

TABAEI, M. AND KULSHRESHTHA S.K. BIOSTRATIGRAPHICAL INVESTIGATIONS OF PABDEH FORMATION IN KABIRKUH ANTICLINE, LURESTAN, IRAN

107

TABAEI M. AND SINGH, R.Y. PALAEOENVIRONMENT AND PALAEOECOLOGICAL SIGNIFICANCE OF MICROFORAMINIFERAL LININGS IN THE AKLI LIGNITE, BARMER BASIN, RAJASTHAN, INDIA

108

TABAEI, M. AND SINGH, R.Y. PALYNOLOGICAL INVESTIGATIONS ON THE LOWER TERTIARY SEDIMENTS OF WESTERN RAJASTHAN, INDIA

109

TABAEI, M. AND YAZDI, M. PRELIMINARY PALYNOLOGICAL INVESTIGATIONS OF AN ARGILITIC INTERVAL IN THE SOH AREA, NORTHEAST OF ESFAHAN, CENTRAL IRAN

110

Contents

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TALENT, J.A., MAWSON, R. AND SIMPSON, A.J. THE "LOST" EARLY ORDOVICIAN (ARENIG)-DEVONIAN (LATEST GIVETIANEARLIEST FRASNIAN) GEORGETOWN CARBONATE PLATFORM

111

TALENT, J.A., MAWSON, R. AND SIMPSON, A.J. SILURIAN TO EARLY CARBONIFEROUS (TOURNAISIAN) PLATFORM-SLOPE SEQUENCES IN EASTERN AUSTRALIA; RECENT ADVANCES IN STRATIGRAPHIC ALIGNMENTS

114

TRINAJSTIC, K.M. CONODONTS, THELODONTS AND PHOEBODONTS - TOGETHER AT LAST

121

UYENO, T.T. AND WENDTE, J.C. CONODONT BIOSTRATIGRAPHY IN TWO WELLS OF THE BEAVERHILL LAKE GROUP, UPPER MIDDLE TO LOWER UPPER DEVONIAN, CENTRAL ALBERTA, CANADA

122

VEVEL, Y.A., ZHURAVLEV, A.V., KOSSOVAYA, O.L. AND SOBOLEV, D.B. LOCHRIEA CRUCIFORMIS ZONE (LOWER CARBONIFEROUS) AND ITS CORRELATION WITH FORAMINIFER AND CORAL SUBDIVISIONS (NORTH OF URALS, IZYAYU SECTION)

123

WANG, X. THE TREMADOC (ORDOVICIAN) GRAPTOLITE DIVERSIFICATION EVENTS

124

WARNE, M.T. PALAEO-GEOMORPHOLOGICAL SIGNIFICANCE OF MIOCENE AND PLIOCENE EURYHALINE OSTRACODA IN THE NEPEAN 1 BOREHOLE, PORT PHILLIP BASIN, SE AUSTRALIA

126

WEBBY, B.D. IN SEARCH OF TRIGGERING MECHANISMS FOR THE GREAT ORDOVICIAN BIODIVERSIFICATION EVENT

129

WINCHESTER-SEETO, T. EARLY AND MIDDLE ORDOVICIAN CHITINOZOANS FROM THE CANNING BASIN, WESTERN AUSTRALIA; A REAPPRAISAL OF THE WORK OF COMBAZ & PENIGUEL (1972) AND THE BIOSTRATIGRAPHIC IMPLICATIONS.

131

YAZDI, M. AND BROCK, G.A. NAMURIAN (CARBONIEROUS) HOLOTHURIAN SCLERITES, FORAMINIFERA AND CONDONTS FROM THE SHOTORI RANGE, EASTERN IRAN

133

ZANG, W. EARLY ORDOVICIAN ACRITARCHS IN THE WARBURTON BASIN, AUSTRALIA

134 SOUTH

ZHAN, R. AND RONG, J. GRADIENT ANALYSIS OF MID ASHGILL BRACHIOPOD BIODIVERSITY IN EAST CHINA

136

ZHANG, J., BARNES, C.R. AND COOPER, B.J. MIDDLE ORDOVICIAN CONODONTS FROM THE STOKES SILTSTONE IN THE AMADEUS BASIN (CENTRAL AUSTRALIA)

137

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Contents

ZHANG, S. AND BARNES, C.R. BIOFACIES PARTITIONING AND RESPONSE TO EUSTATIC CHANGES OF LLANDOVERY (EARLY SILURIAN) CONODONTS, ANTICOSTI BASIN, QUEBEC, CANADA

138

ZHEN, Y., PERCIVAL, I.G. AND WEBBY, B.D. EARLY ORDOVICIAN (BENDIGONIAN) CONODONTS FROM CENTRAL NEW SOUTH WALES, AUSTRALIA

139

ZHOU, Z., ZHOU, Z. AND YUAN, W. LLANVIRN-EARLY CARADOC TRILOBITE BIOFACIES OF WESTERN HUBEI AND HUNAN, CHINA

140

ZHURAVLEV, A. V. CONODONT RESPONSE ECOLOGICAL EVENT

141 TO

THE

MID-VISEAN

(EARLY

CARBONIFEROUS)

SECTION II Posters ANDERSON, M. A STUDY OF BELODELLA AND NEOPANDERODUS WITH EMPHASIS ON FAUNAS FROM EASTERN AUSTRALIA

142

ATAABADI, M.M. AND RAHMANI, K.A. RECOVERY OF LATE DEVONIAN FLORA FROM KERMAN AREA, SOUTH EAST IRAN

143

AUNG, A.K. DEVONIAN OF SHAN STATE, MYANMAR

144

BAARLI, B. G., JOHNSON, M.E. AND ANTOSHKINA, A.I.. SILURIAN STRATIGRAPHY AND PALAEOGEOGRAPHY OF BALTICA

146

BASDEN, A. THE MOST PRIMITIVE OSTEICHTHYAN BRAINCASE?

147

BRIME. C., TALENT, J.A. AND MAWSON, R. TRANSITION FROM DIAGENESIS TO METAMORPHISM IN THE PALAEOZOIC SEQUENCES OF THE TOWNSVILLE HINTERLAND OF NORTHEASTERN AUSTRALIA

148

BURROW,C.J. CHANGES IN MICROVERTEBRATE FAUNAL ASSOCIATIONS THROUGH THE LOWER DEVONIAN OF SOUTH-EASTERN AUSTRALIA

149

CANRTILL, R.C. AND BURRETT, C.F THE GREATER GONDWANA DISTRIBUTION OF THE MIDDLE ORDOVICIAN

151

C O N O D O N T PANDERODUS

NOGAMll

(LEE, 1975)

DARGAN, G. SPONGE-CORAL MUTUALISM: A SILURIAN EXAMPLE

152

ENGELBRETSEN 1M. MIDDLE TO LATE ORDOVICIAN ACROTRETOID LINGULATE BRACHIOPODS FROM THE MOLONG VOLCANIC BELT, CENTRAL NSW

153

Contents

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ENGELBRETSEN, M., FARRELL, J., MATHIESON, D. AND PICKETT, J. GIANT BIVALVES FROM THE SILURIAN MOLONG LIMESTONE, WESTERN NSW

1 54 CENTRAL

FARRELL, J.R. REWORKED SILURIAN AND ORDOVICIAN CONODONTS WITHIN THE LATE DEVONIAN CATOMBAL GROUP F R t D A , J., AND ROHR, D.M. PALAEOGEOGRAPHY OF ORDOVICIAN ANALYSIS

155

156 GASTROPODS

PRELIMINARY

GIRARD, C. AND RENAUD, S. MORPHOLOGICAL RESPONSE OF CONODONTS TO KELLWASSER ANOXIC EVENTS

158

GHOLAMALIAN, H., TURNER, S., BURROW, C.J. AND YAZDI, M. RECOVERY OF LATE DEVONIAN (FRASNIAN) MICROVERTEBRATES AND CONODONTS FROM THE CHAHRISEH AREA, NORTH EAST OF ESFAHAN, IRAN

159

JONES, P.J. AND FOSTER, C.B. LATE PERMIAN (KAZANIAN) OSTRACODS, AND ASSOCIATED PALYNOMORPHS, FROM THE PETREL SUB-BASIN, NORTHWESTERN AUSTRALIA

160

KHAN, F.R. SEA LEVEL CHANGES WITH REFERENCE TO CONODONT BIOFACIES IN THE FRASNIAN TO FAMENNIAN AT THE COL DES TRIBES (MONT PEYROUX) AND TOURRIER (CABRRIERES), MONTAGNE NOIRE, SOUTHERN FRANCE.

161

KRAFT, P. AND KRAFT, J. POSSIBLE HYDROID FROM THE BOHEMIAN ORDOVICIAN

162

LEE, D-J. AND ELIAS, R.J. GROWTH CHARACTERISTICS IN SOME EARLY TABULATES (LATE ORDOVICIAN; MANITOBA, CANADA), AND THEIR PALAEOBIOLOGIC AND PHYLOGENETIC IMPLICATIONS

163

MATHIESON, D.K. INVESTIGATION OF CONODONTS COLOUR ALTERATION INDEX FROM THE BOOTH LIMESTONE SOUTH OF COBAR, NEW SOUTH WALES, AUSTRALIA

164

MAWSON, R AND SMITH, D. SILICIFIED EARLY DEVONIAN (LOCHKOVIAN) WINDELLAMA, SOUTHEASTERN AUSTRALIA

165 GASTROPODS

FROM

MELCHIN, M.J. AND HOLMDEN, C. CARBON ISOTOPE STRATIGRAPHY OF THE MID-ASHGILL (LATE ORDOVICIAN) TO LOWER TELYCHIAN (EARLY SILURIAN) OF THE CAPE PHILLIPS FORMATION, CENTRAL CANADIAN ARCTIC ISLANDS

166

MULLINS, G.L., ALDRIDGE, R.J. AND SIVETER, D.J. ACRITARCH AND PRASINOPHYTE ALGAE OF THE WENLOCK. AND LUDLOW SERIES (SILURIAN) OF THE TYPE AREAS

167

NOBLE, P. J. A COMPOSITE SILURIAN RADIOLARIAN BIOZONATION FOR NORTH AMERICA AND EURASIA

168

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Contents

PARKES, R., SIMPSON, A. AND FARRELL, J. A LATE SILURIAN ACANTHODIAN FROM COEVAL CARBONATES IN VICTORIA, NEW SOUTH WALES AND SOUTHERN CHINA

170

PERCIVAL, I.G., WEBBY, B.D. AND PICKETT, J. ORDOVICIAN (BENDIGONIAN TO EASTONIAN) INVERTEBRATE FAUNAS FROM THE NORTHERN MOLONG VOLCANIC BELT OF CENTRAL NEW SOUTH WALES

171

RAY, D.C. SUBSURFACE FACIES ANALYSIS OF THE MUCH WENLOCK FORMATION (SILURIAN), ENGLAND

172 LIMESTONE

RICKARDS, RB., HAMEDI, M.A. AND WRIGHT, A.J. AN UNUSUAL LATE ARENIG ASSEMBLAGE OF GRAPTOLITES, RHABDOPLEURAN HEMICHORDATES AND CHITINOUS HYDROIDS FROM THE BANESTAN AREA, EAST-CENTRAL IRAN

173

SIMPSON, A. A BRIEF HISTORY OF SILURIAN TIME USING CONODONTS

175

SIMPSON, A. LATE ORDOVICIAN CONODONTS FROM THE "CARRIERS WELL FORMATION", NORTHEASTERN AUSTRALIA

177

VALENTINE, J.L. SILICIFIED EMSIAN (EARLY DEVONIAN) BRACHIOPODS FROM THE MURRINDAL LIMESTONE, BUCHAN, VICTORIA.

179

WINCHESTER SEETO, T. AND McILROY, D. THE EARLIEST RECORD OF FORAMINIFERAL LININGS AND MELANOSCLERITES FROM THE LOWER CAMBRIAN LONTOVA FORMATION, ST PETERSBURG, RUSSIA

180

YAZDI, M. AND MANIZHEH SHIRANI, M. FIRST REPORT OF AN ICHTHYOLITH FAUNA CLOSE TO THE PERMIAN TRIASSIC BOUNDARY FROM A SECTION IN SOUTH OF ESFHAN, CENTRAL IRAN

181

YAZDI, M. AND RABLEY Z. FIRST REPORT OF PROBABLY CARBONIFEROUS MICROVERTEBRATES FROM THE DARCHALEH AREA (EASTERN SHAHREZA, IRAN)

182

ZIMMERMAN, M.K., NOBLE, P.J., HOLMDEN, C. AND LENZ, A.C. GEOCHEMISTRY OF EARLY SILURIAN (WENLOCK) GRAPTOLITE EXTINCTIONS: CAPE PHILLIPS FORMATION, ARCTIC CANADA

183

Papers

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THE HELIOPYGE SP. NOV. (ASTEROPYGINAE: TRILOBITA) FROM THE SOH AREA, CENTRAL IRAN ARTABAZ ADHAMIAN and MANSORH GHOBADI POUR Department of Geology, University of Esfahan, Iran A new species of the trilobite genus Heliopyge is described from the middle part of a stratigraphic section in Soh area, north of Esfahan. Contemporaneous condonts reported by Adhamian (2000, in press) include Bipennatus bipennatus, Neopanderodus aequabilis and Polygnathus pseudofoliatus suggesting a Givetian (Early to Middle varcus Zone) age. An argillaceous horizon at the top of the section contains reworked trilobites and brachiopods. The absence of Frasnian to Early Permian sediments in the area confirms the presence of a hiatus in the Soh area, that probably coincides with Hercynian epirogenetic movements in Iran. REFERENCES ADHAMIAN, A . ( 2 0 0 0 in press). Middle Devonian (Givetian) conodonts from Soh area, Central Iran. Records of

Western Australian Museum.

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Papers

SEQUENCE AND EVENT STRATIGRAPHY OF THE MEDIAL SILURIAN OF EASTERN NORTH AMERICA: COMPARISON OF NEW YORK AND SOUTHERN OHIO/NORTHERN KENTUCKY CARLTON E. BRETT and DAVID C. RAY Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, USA Recent comparative study of outcrops of upper Llandovery to Wenlock strata in southern Ohio-northern Kentucky has revealed marked similarities in overall sequence patterns to those previously documented (and designated S-l to S-6) in the better known northern Appalachian Basin (Ontario, New York, Pennsylvania). Moreover, this work has led to the discovery of K-bentonites and seismites that may facilitate event correlation. In south central Ohio, a thin, glauconitic carbonate (Dayton Limestone; mid Telychian?) oversteps a regionally angular unconformity that bevels older Silurian strata westward onto the Findlay Arch. Overall, the Dayton appears to represent a transgressive systems tract (TST) associated with a major late Llandovery sea level rise. The overlying greenish gray Estill Shale, has yielded conodonts of the Pterospathodus amorphognathoides Zone; it appears to represent the late Telychian highstand systems tract (HST). The upper portion of the Estill Shale Member (Crab Orchard Formation; late Telychian) rests with subtle unconformity on lower maroon colored Estill Shale in the eastern outcrop belt. Together, Dayton and Estill comprise a "fourth order" sequence equivalent to S-4 (Westmoreland-Willowvale-uppermost Rose Hill) in the Appalachian Basin. Sandy dolostones variably assigned to the uppermost Estill or lower Bisher Formation rest sharply on the Estill green shales and comprise the equivalent of the Rockway-Dawes (sequence S-4B) of New York. A series of newly discovered Kbentonites in the upper Estill may correlate with those found in the Willowvale Shale. Dolomitic, sandy, crinoidal pack- and grainstones in the lower Bisher Formation (lower Wenlock) that sharply overlie the S-4B strata. These beds appear to be coeval with the Irondequoit Limestone of New York and Ontario and the Keefer Sandstone of the northern Appalachian basin, which constitute the TST of sequence S-5. Locally, in south central Ohio, the crinoidal dolostones are overlain by up to 3 m of gray, fossiliferous, dolomitic shale ("upper Bisher Formation") that appears to represent a tongue of Rochester Formation, the HST of sequence S-5. However, this shale is cut out by unconformities to the southeast in Ohio and adjacent Kentucky. Locally, a bed of sandy dolostone, displaying convoluted bedding (seismite?) intervenes between the shale and overlying sandy crinoidal dolostones of the Lilly Formation. This bed may represent the DeCew Dolostone, a unit which shows deformation over much of western New York and southern Ontario. If so, this horizon may represent an extremely widespread seismite. The sharply erosional base of the Lilly Formation (mid-upper Wenlock) may represent the sequence 5-6 boundary at the base of the Lockport Group in the northern Appalachian basin. Crinoidal dolostones (TST of S6) are overlain by argillaceous dolostones with local bioherms, comparable to the Gasport reef zone (HST of S6) in western New York. Thin K-bentonites in the Lilly Dolostone may provide a link with those recently discovered in the Gasport Formation. These results confirm that sequence boundaries recognized in the Appalachian basin can be extended into the midwestern. Overall, these patterns suggest that widespread volcanogenic and seismic events associated with early phases of the Salinic Orogeny are superimposed on allocyclic eustatic sea-level fluctuations.

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THE PRESERVATION AND RECONSTRUCTION OF FOSSILS FROM THE HEREFORDSHIRE (SILURIAN) LAGERSTATTE DEREK E.G. BRIGGS , PATRICK J. ORR * , DAVID J. SIVETER , DEREK J. SIVETER ' and MARK D. SUTTON 1

2 5

1 2 3 4 5

Department of Earth Sciences, University of Bristol, Queen's Road, Bristol BS8 1RJ, UK Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK Current address: Department of Geology, National University of Ireland, Galway, Ireland Department of Geology, University of Leicester, University Road, Leicester LEI 7RH, UK Geological Collections, University Museum of Natural History, Oxford OX1 3PW, UK

Three-dimensional preservation of non-biomineralized fossils occurs in carbonate concretions in a volcaniclastic deposit from the Wenlock Series of Herefordshire, England. Specimens are preserved in calcite, the texture of which investigated in a new arthropod indicates that it constitutes void infill. Calcite forms a cast of the external surface of the specimens, having precipitated after decay of even the most recalcitrant biological tissues. Incorporation of the fossils into concretions ensured their long-term preservation but was not, at least in most examples, responsible for preventing collapse and occlusion of voids in the interval between tissue decay and the precipitation of calcite. The precipitation and/or accumulation of clay minerals adjacent to specimens during decay was important in this process, as was possibly the geotechnical properties of the ash. Interpretation of two-dimensional sections of the fossils, produced by splitting the nodules, is problematic. Recovering these calcitic specimens by acid digestion methods is clearly not an option. There is also difficulty in isolating the fossils from their matrix by mechanical methods because of their size and, often, their intricate external morphology. To overcome these problems in acquiring three-dimensional morphological information, a technique has been developed based on serial grinding and digital photography. Photographic datasets are processed digitally to produce volume models of the fossil for three-dimensional visualization. The models are rendered either directly to produce virtual X-ray images, or preferably by the computation of isosurfaces which are then rendered by ray-tracing. Static images are rendered from sequential angles and then combined to produce video files of the fossil spinning in space. Reconstructions produced in this way can be easily retouched and manipulated to remove 'noise' and preservational artifacts, to dissect out structures for detailed study, or to combine part and counterpart of the specimen into a single reconstruction. This technique has already extracted previously unattainable morphological information from the Herefordshire material and forms the basis for ongoing study of the biota.

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CAMBRIAN FAUNAS FROM MOUNT ARROWSMITH, NORTH-WESTERN NEW SOUTH WALES, AUSTRALIA GLENN A. BROCK1 and IAN PERCIVAL2 1

Centre for Ecostratigraphy & Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Specialist Services Section, Geological Survey of New South Wales, P.O. Box 76, Lidcombe, N.S.W. 2141, Australia

Mount Arrowsmith, situated in the far west of N.S.W., 200 km north of Broken Hill, lies at the north-western extremity of the Koonenberry Belt. Unconformably overlying Neoproterozoic alkaline volcanics and metasediments, which form the bulk of the mountain, are Early Palaeozoic sedimentary rocks. Formal definitions are provided for formations of Cambrian age at Mount Arrowsmith, comprising the Gnalta Group. The oldest fossiliferous unit is the Pincally Formation, of early Middle Cambrian (Ordian-Early Templetonian) age, composed of shales and thin-bedded limestones with a total thickness of 130 m. Fauna present includes the Ungulate brachiopods Eothele granulata ROBERTS, Hadrotreta djagoran KRUSE, lAngulotreta sp. Micromitra sp., molluscs Pelagiella, Helcionella, chancelloriids, hyolithids, hyolithelminthes, echinoderm sclerites, and problematic forms. The phosphatic assemblage closely resembles synchronous sequence 1 faunas from the "first discovery limestone" Member of the Coonigan Formation (ROBERTS & JELL 1990), carbonate sequences from the Daly, Wiso and Georgina basins from northern Australia (KRUSE 1990 1998) and the Arrowie and Stansbury basins in South Australia (BROCK & COOPER 1993). Conformably overlying the Pincally Formation is the Wydjah Formation, dominated by quartzose sandstones in its lower and upper parts; interbedded shales and thick oncolitic dolostones in the middle of the unit comprise the Pimpira Member. The dolostones contain a sparse fauna dominated by hyolithids and algae, with rare Ungulate brachiopods {Hadrotreta sp. and Eoobolus sp.). No fossils have been recorded in the overlying Wyarra Shale, but as this formation is relatively thin and conformably overlies the Wydjah Formation it is unlikely that the two units are markedly different in age. The Cambrian section is unconformably overlain by (or faulted against) the Yandaminta Quartzite and overlying Tabita Formation (comprising the Mootwingee Group), of Early Ordovician age. The interval of missing time represented by the stratigraphic break corresponds to the Delamerian Orogeny. The more precise age derived from study of the Cambrian fauna of the Pincally and Wydjah formations enable enhanced regional correlations along the Koonenberry Belt. REFERENCES BROCK, G.A. & COOPER, B.J., 1993. Shelly fossils from the Early Cambrian (Toyonian) Wirrealpa, Aroona

Creek, and Ramsay Limestones of South Australia. Journal of Paleontology 67, 758-787. KRUSE, P.D., 1990. Cambrian palaeontology of the Daly Basin. Northern Territory Geological Survey, Report 7,

1-58. KRUSE, P.D., 1998. Cambrian palaeontology of the eastern Wiso and western Georgina Basins. Northern Territory Geological Survey, Report 9, 1-68. ROBERTS, J. & JELL, P.A., 1990. Early Middle Cambrian (Ordian) brachiopods of the Coonigan Formation,

western New South Wales. Alcheringa 14,257-309. [2Published with permission of the Director General, N.S.W. Department of Mineral Resources.]

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PALAEOECOLOGY AND DISTRIBUTION OF SHALLOW-WATER RUGOSE CORALS IN THE MIDDLE AND UPPER DEVONIAN REEF COMPLEXES, CANNING BASIN, WESTERN AUSTRALIA. R.L.S. BROWNLAW and J.S. JELL. Department of Earth Sciences, The University of Queensland, Queensland, 4072, Australia Middle to Upper Devonian reef complexes are exposed extensively on the Lennard Shelf, Canning Basin, northwestern Australia. Carbonate deposition commenced in the basin during the middle Givetian and continued through to the late Famennian, with two major cycles of reef development. The Givetian-Frasnian reef cycle (Pillara Cycle) is considered to have formed during a transgressive phase and is characterised by vertical accretion punctuated by several backsteps. Initial deposition reflects a shallow open marine environment in a carbonate ramp setting, with localised hypersaline deposits. True reef-rimmed shelves did not develop until the Frasnian. The Famennian reef cycle (Nullara Cycle), arguably formed in regressive conditions during slow subsidence, is characterised by strongly prograding reef-rimmed shelves. While rugose corals form a conspicuous part of the fauna within the reef complexes, they are rarely found at platform margins, and are not considered major reef builders. The majority of corals are restricted to bioherms (Givetian) and biostromes (Frasnian) within the Pillara Limestone. Corals are also locally plentiful in the upper fore-reef slope strata of the Sadler Limestone, Virgin Hills Formation, and Napier Formation, and in the Sparke Conglomerate. Six (one Givetian and five Frasnian) rugose coral-bearing depositional environments are recognised. 1) Givetian ramp: corals are dominated by solitary (Temnophyllum spp., Grypophyllum spp., Chostophyllum sp., Aristophylluml sp., and Spinophylluml sp.) and cerioid (Careophyllum sp.) forms, with rare fasiculate (Sociophyllum sp.) corals. They occur as scattered individuals or more typically as biohermal mounds. The mounds comprise a framework of cerioid rugosans and tabular to massive stromatoporoids, with small solitary corals flanking the sides. 2) Lower Frasnian isolated platform: corals are abundant and typically fasiculate {Disphyllum spp.) or cerioid (Argutastrea sp.). They occur in cyclic back-reef biostromes. The shallowing-upwards cycles comprise eight carbonate facies, of which the coral facies is considered to represent the deepest phase. 3) Middle to upper Frasnian outer fringing reef: corals are rare, but when present are fasiculate (Disphyllum spp.). They occur in cyclic back-reef biostromes. The shallowing-upwards cycles comprise a mix of carbonate and siliciclastic facies, with the coral bearing lithologies representing the deepest phases. 4) Middle to upper Frasnian inner fringing reef: corals are abundant and consist of solitary (Novaphyllum sp., Tabulophyllum sp.), fasiculate to aphroid (Smithiphyllum sp.), and thamnastreoid (Phillipsastrea sp.) forms. They occur within siltstone horizons within the conglomerates. The conglomerates are cyclic, with the siltstones considered to represent the deepest facies in the overall deepening upwards cycles. 5) Middle to upper Frasnian fore-reef slope: corals are typically rare in the fore-reef slope, but may be locally abundant and in situ. They are typically fasiculate (Thamnophyllum spp and Peneckiella spp.), but solitary {Hillastraea sp.) and thamnastreoid (Kuangxiastraea sp, Frechastraea sp., and Hillastraea sp.) forms are locally common. 6) Latest Frasnian fore-reef slope bioherm: corals are abundant, with both solitary (Spinophyllum sp.) and thamnastreoid (Frechastraea sp.) forms present. The bioherms also contain brachiopods, Renalcis and stromatolites, and probably represent downslope accumulations during platform exposure in the latest Frasnian. Shallow-water rugose corals are common within the reef complexes of the Canning Basin and their distribution can be closely related to six distinct depositional environments.

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DISCOVERY OF EUCONODONT NEW SKELETAL ELEMENT G.I. BURYI1 and A.P. KASATKINA2 1 2

Far East Geological Institute of Far Eastern Branch, Russian Acad. Sci., Vladivostok, 690022, Russia Pacific Oceanological Institute of Far Eastern Branch, Russian Acad. Sci., Vladivostok, 690041, Russia

Euconodonts or representatives of euconodontophyles are marine worm-like invertebrates. Their isolated microscopic skeletal remains, known as conodonts, are a very important biostratigraphic faunal group for Paleozoic and Triassic deposits. Many discoveries of these elements in natural accumulations have shown them to belong to a mouth apparatus made up of conodont elements of differing morphologies including cones, ramiform and platform elements. The mouth apparatus probably provided the animal with food by catching prey, filtering water through the branched net of teeth, and crushing the filtered prey using thicker platform elements. It is apparent that the mouth apparatus was rather robust requiring a strong muscle system. We think that in the euconodont head part, there was a common mouth complex possibly composed of a pharynx, conodont elements of mouth_apparatusA a muscle system connecting and directing these elements and paired skeletal elements in the place of the attachment of muscles to the animal body working for elastic resistance. Chaetognaths, animals similar to euconodonts, have a light prehensile apparatus composed of chitinous grasping spines and denticles, which is attached to the body with the aid of two elongated, semi-transparent plates arranged on the ventral and dorso-ventral sides of the head. In our opinion, such skeletal head plates also existed in euconodonts. These lobate structures were located on the anterior of the conodont apparatus in several specimens from the Carboniferous Granton shrimp bed of Edinburgh, and the Upper Ordovician Soom Shale of South Africa. These lobate structures were considered soft tissues of conodont animal and were interpreted as sclerotic cartilages surrounding eyes or as eye capsules. From Lower Triassic deposits of the South Primorye (Kamenushka River), dated as Neogondolella milleri conodont zone and locally as the Anasibirites nevolini ammonoid zone, a new skeletal element has been found (Fig. 1). It resembles the Upper Ordovician and Carboniferous lobate structures of conodont animal. At the same time, in its physical characteristics this plate is analogous to isolated conodont elements found with it at this location. We believe that this previously unknown skeletal element of a euconodontophyle animal is its head attaching plate. It resembles a flattened plate of irregular rounded shape. Its major axis is 0.72 mm and minor axis is 0.57 mm. The thickness of the plate along the outer margin is about 0.1 mm. The outer margin of the plate is uneven with abundant projections. At a distance of 0.2 mm from the outer margin, in parallel to it, the inner margin of this plate extends hanging over its surface in the form of an edge or a narrow ridge bearing hardly visible projections or papillae. We suggest that just to that ridge and to the projections of the outer margin of the plate, the muscles, maintaining and directing the conodont elements of the mouth apparatus, were attached. In the center of the plate, there is a subtriangular hole. Fig.l Head attaching plate of a euconodont This work was supported by the Russian Foundation of Basic Research (grant No 98-04-49355).

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HIRNANTIAN GRAPTOLITE DIVERSITY CHANGES FROM THE YANGTZE REGION CHEN XU1, FAN JUN-XUAN1, and C.E. MITCHELL2 1 2

Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing 21008, China Department of Geology, SUNY at Buffalo, Box 603050, Buffalo, NY 14260-3050, USA

The present study of graptolite diversity changes through the Hirnantian and the Ordovician-Silurian extinction to new recovery and radiation bioevents is based on a large number of new data in the Yangtze region. It is gathered from four continuous and closely sampled sections that were examined recently, as well as 30 other sections which one of us (CHEN) and his colleagues have investigated in the past. Abundant new data provide data for a re-examination of the patterns and process of mass extinction and recovery of planktonic graptolites during the Hirnantian Substage with relation to diversity change. The graptolite zonation through the Ashgill to early Rhuddanian interval from the Yangtze region have been summarised elsewhere. The sections from Ludiping and Honghuayuan in the south (along the Dianqian oldland) to the sections at Wangjiawan and Fenxiang of Yichang in the central Yangtze platform area display a diachronous facies change from shallow water to deeper water environments. If the diversity of genera and species is tracked through successive samples at each of these four sections, we find that the timing of the first extinction episode is different between the shallow-water and more basinal sections. In particular, the relatively shallow water sites experienced extinction earlier, within the D. mirus Subzone, whereas in the deeper water areas the main extinction took place within the N. extraordinarius-N. ojsuensis Zone proper. Dating for the second episode in this double mass extinction event is rather more difficult than for the initial, larger event. However, the fact that the whole DDO graptolite fauna disappeared by the upper N. persculptus Zone indicates a big event in graptolite macroevolution, which coincides with the second extinction phase. We have compiled data on the number of victim graptolite families, genera and species during the double mass extinction in the following table. First episode

Second episode

3 extinct from total 4 families, occupying 75%

Genus

15 extinct from total 25 genera, occupying 60%

3 extinct from total 8 genera

Species

67 extinct from total 83 species, occupying 80.7%

10 extinct from total 28 species, occupying 35.7%

Family

The entire Ashgill graptolite radiation - double mass extinction - survival -recovery scenario can be defined based on data from the Yangtze region. Among the extinction taxa, most of the endemic and specialised forms expired before the first extinction episode. A few exceptions finally died out before the second phase of extinction. Two additional species, represented by only a few individuals near the top of their range, died out a little after the second episode. The survival-recovery interval between the two extinction episodes includes 18 survivor species among 10 genera of the DDO fauna, as well as 14 newly appearing species belonging to 4 genera of the Normalograptidae and Petalolithidae. Thus, it is difficult to single out a distinct survival interval after either the first or second extinction episode. The extinction - recovery process may be more complicated than the regular pattern suggested by previous authors. Disaster taxa have been recognised from the interval after the second extinction phase. The biologic factors most strongly correlated with graptolite mass extinction are mainly population size (proportional to geographic range), specialised colony structure (perhaps reflecting specialised habits), and probably some factor related to the genetic pattern of the proximal end of the rhabdosome. The present study is a contribution to the IGCP project 410.

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ORDOVICIAN SERIES AND STAGES IN CHINESE STRATIGRAPHY: STEPS TOWARD A GLOBAL USAGE CHEN XU, ZHOU ZHI-YI, RONG JIA-YU and LI JUN Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China The first Chinese Ordovician Series was erected by Lee in 1924. Since then, many regional Orodovician series and stage names have been erected and mostly published into Chinese. The present study is a review of these regional units with a discussion of their definitions and correlation to the international standard. Among them, the Ichang Series, Neichiashan Series, Chientangkiang Series, Yushanian Stage and Dawanian Stage are most important. The Lower, Middle and Upper Ordovician Series with their new definitions (WEBBY 1998) are now formally accepted in China. The global stage names, which have be approved (Tremadocian and Darriwilian), and "Caradocian" and "Ashgilian", which are potentially to be global standard, should be formally used in China. Only two regional stage names, the Yushanian and Dawanian, still remain since the international correlation of these two units have not yet been solved.

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ORDOVICIAN TRILOBITE FAUNAS AND DEPOSITIONAL HISTORY OF THE TAEBAEKSAN BASIN, KOREA: IMPLICATION FOR PALAEOGEOGRAPHY D.K. CHOI, D.H. KIM, and J.W. SOHN School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea The Taebaeksan Basin occupies the mid-eastern part of the Korean Peninsula and comprises mainly the carbonate-dominated Choson Supergroup (Cambrian-Ordovician) and clastic-dominated Pyongan Supergroup (Carboniferous-Triassic). The Choson Supergroup has been known to contain two contrasting Cambrian faunas: the Cambrian trilobite assemblages of the Taebaek Group belong to the Hwangho faunal province characterised by endemic taxa representing a shallow shelf habitat, whereas those of the Yongwol Group are comparable to the Jiangnan fauna which is dominated by cosmopolitan and pelagic forms indicating a deep-water oceanic environment. In contrast, the Ordovician trilobite faunas of both the Taebaek and Yongwol groups, representing shallow marine facies, are closely similar to each other and thus more significant in assessing the early Palaeozoic continental configuration around the Korean Peninsula. In the Taebaeksan Basin, trilobites are among the most dominant fossil group in the Early Ordovician; they become less important in Middle Ordovician faunal assemblages. The Yosimuraspis Zone of the Yongwol Group represents the earliest Ordovician zone in the Taebaeksan Basin, the base of which marks the CambrianOrdovician boundary in Korea. The poorly documented Pseudokainella Zone of the Taebaek Group may also be assignable to the early Tremadoc. The middle Tremadoc Kainella Zone of the Yongwol Group is apparently older than the Asaphellus Zone of the Taebaek Group. The succeeding late Tremadoc Shumardia Zone of the Yongwol Group shares a number of taxa with the Asaphellus and Protopliomerops zones of the Taebaek Group. The early Arenig Kayseraspis Zone has been documented from both the Taebaek and the Yongwol groups. The youngest trilobite fauna recognised in the Taebaeksan Basin is the Dolerobasilicus fauna of Darriwilian age. During the Ordovician the Taebaeksan Basin is inferred to have been a low-relief continental shelf, sporadically spotted with shoals, lagoons, and tidal flats. At the beginning of the Ordovician, shoal-water and lagoonal carbonate sediments were deposited in the offshore areas, while sand beach environment occupied the eastern margin of the basin. Rapid sea-level rise in the Kainella Zone (or Asaphellus Zone) time drowned the carbonate platform forming an open marine condition across the Taebaeksan Basin, while the beach environment was displaced beyond the eastern edge of the Taebaeksan Basin. This open shelf persisted throughout the late Tremadoc and early Arenig times. Near the end of Kayseraspis Zone time, the open shelf setting was replaced by lagoonal and tidal flat environments. These lagoonal and tidal flat environments were generally hypersaline, but intermittently flooded by normal marine waters. The termination of hypersaline peritidal environments was followed by the Darriwilian (or Llanvirn) marine transgression. As water depth increased, the formerly tidal flat environment was capped by subtidal, lagoonal or restricted marine setting. The final stage of the Taebaeksan Basin is represented by the extensive development of carbonate shoals. The marine sedimentation ceased over the whole Taebaeksan Basin in the Late Ordovician, and most of the Korean peninsula became emergent during the mid-Paleozoic until marine transgression resumed in the late Carboniferous. The Ordovician trilobite faunas of the Taebaeksan Basin are characterized by the common occurrence of pandemic trilobites such as Jujuyaspis, Kainella,, Leiostegium, Asaphellus, Shumardia, Apatokephalus, Hystricurus, Protopliomerops, Asaphopsoides, and Kayseraspis. Trilobite taxa with restricted distribution are Yosimuraspis, Koraipsis, Hukasawaia, Seisonia, Chosenia, and Dolerobasilicus. These shallow marine trilobite faunas show a strong biogeographic link to North China and, to a lesser degree, to Australia and South China. During the early Paleozoic the Taebaeksan Basin was a shallow carbonate shelf, which was connected through contiguous shallow waters to the North China block. This is a contribution to IGCP project no. 410 "The Great Ordovician Biodiversification Event"

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HONEYCOMBE-TEMPLATE-PATTERN-LIKE MINERAL-OCCLUSION PROBLEMATICA OF CLOSED OSTRACOD CARAPACES IN LOWER SILURIAN LIMESTONES OF MIDWESTERN NEW SOUTH WALES EXPLAINED AS FOSSILISED TRAPPED TAPHONOMIC GAS-BUBBLE COMPLEXES THAT FORMED DIAGENETICALLY AT SHALLOW BURIAL DEPTHS PATRICK J. CONAGHAN1 and GUNTHER C.O. BISCHOFF2'3 1

Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia 3 Deceased 2

Acetic-acid-residues of Lower Silurian limestone samples treated for the recovery of conodonts by BISCHOFF (1986) contain extremely large numbers of ostracods. Most of these occur in the form of bean-shaped internal moulds of closed complete carapaces or, due to separation along the median-/hinge-plane during the acid dissolution, of moulds of single valves. The ostracod fauna consists of about 11 species. As can be judged from partly acid-etched specimens, internal moulds, and thin-sections, all of them are smooth externally or are, at most, weakly ornamented. Confident identification to species or even generic level is impossible due to the loss of diagnostic morphological features during acid treatment. Tentative assignations to generic level are, eg., Bairdiocyprisl sp., Baschkirincf! sp., Krausellal sp., and Microcheilinellcf! sp. Study of the morphological details of these internal moulds by binocular, scanning-electron, and thin-section microscopy, and EDS and XRD analyses of the decalcified mineral-matter of which they are composed, allows elucidation of the genesis of the internal moulds as well as that of a variety of moldic (acid-etched) structures that many of them contain within, including: (1) incidental entire and fragmentary skeletal allochems of various invertebrates and dasyclad algae; and (2) an enigmatic variety of moldic geometry that is characteristically regularly or irregularly cellular in planimetric view and resembles an inverse-honeycomb-template-like pattern in which the cross-sectional (planimetric) shape of the individual cells is typically either circular or polygonal (and predominantly hexagonal). The decalcified ostracod moulds are composed predominantly of a spongy (micro-porous) three-dimensional interlocking meshwork of clay/phylsil crystals and sporadic microscopic euhedral authigenic quartz crystals. SEM images and EDS and XRD analyses of the clay/physil substrate demonstrates it to be mineralogically heterogenous, comprising predominantly: chlorite, smectite, nontronite, corrensite, and vermiculite. These authigenic clay/physil crystal-platelets are commonly straight-sided, have polygonal outlines, range from about 2 to 10 ^im in diameter, and intersect/interlock in what appears to be a geometrically random pattern, but in other places form a more regular boxwork manifesting subrectangular, rhombic, and polygonal (including hexagonal) outlines, commonly enclosing angles that measure about 60° or 120°. The diameters of the tiny pore-spaces that are enclosed by the clay/physil platelets vary in wide limits from 0.45 nm to 10 jim and in some cases even to 40 jim. Both the geometrical evidence regarding the nature of these micro-pores and the knowledge that the material that is now missing from them is a result of its solubility in weak acid, proves its identity to be calcite — a conclusion that is confirmed (and refined to be ferroan-calcite) by scrutiny of the authigenic-clayey occlusions of closed-ostracod carapaces in carbonate-stained thin-sections of the same rock samples. The internal moulds of carapaces and valves, regardless of whether they are fully occluded by clayey material and authigenic quartz or whether they enclose cavities, are completely (in the case of carapaces) or partly (in the case of valves) delimited by a thin clayey layer that closely reflects (or moulds) the shape of the inner surface of the now-dissolved calcareous valves or valve because it obviously had been in contact with them/it. EDS analyses of this layer suggest its composition is the same as the clayey material that makes up the rest of the internal mould, but it nevertheless seems by comparison with the latter to be firmer and more resistant to breakage. Its outer surface is smooth in most ostracod taxa observed in this study, but it is weakly nodose in some wherein the latter features probably manifest the presence of infilled normal pore canals. This layer is termed herein the "epitaxial layer" (but devoid of the usual connotations of mineral-overgrowth relationship that the term "epitaxial" normally carries). That this epitaxial layer is not an authigenic replacement of the calcareous valves of the ostracods by clay minerals is demonstrated by the presence of more or less deep grooves left by the dissolved smaller valve on internal moulds of some carapaces. Additionally, a firm clayey lamella, referred to herein as the "median lamella" commonly occurs in the zone of the ostracod hinge-plane in some internal moulds. It extends in the form of a sheet from the carapace margins toward the centre and may even cover the entire inner opening of the valve. The exposed surface of the median lamella is flat or very slightly concave, and it is located at a plane defined approximately by the margins of the valve's internal mould. The chemical and mineralogical composition of the median lamella is probably identical to that of the epitaxial layer. The median 19

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lamella, or at least some remnants of it, is present in the vast majority of internal moulds of valves, but it is possibly less common in those of carapaces as can be ascertained by glimpses through fractures in the epitaxial layer of hollow or partly hollow specimens. The foregoing evidence suggests that the epitaxial layer and the median lamella mainly constitute infiltrated detrital (epiclastic) clay/physil particles (subsequently diagenetically regenerated) that accumulated by adsorption onto the chitinous lining respectively of the inner surface of the (now acid-removed) calcareous valves (= calcified part of outer lamella), and of the inner lamella of duplicature. The cavities of interest in this report occur within the space defined by the epitaxial layer and the median lamella (where present) or the plane of its projection in the hinge-zone. The moldic preservation of incidental skeletal allochem inclusions (ostracod instars, tiny gastropods, fragments of dasyclad algae, etc.) in this space manifests their synsedimentary burial within the ostracod carapace by infiltrated clayey internal sediment and/or by the subsequent growth of authigenic clay. That at least some of this clayey material constitutes detrital internal sediment (as opposed to authigenic mineral growth) is demonstrated by the common definition of geopetal structures by such clay in some of the acid-residue internal moulds as well as in intersections of ostracod carapaces in thin-sections of the same rock samples. The enigmatic inverse-honeycomb-template-like moldic cellular pattern also occurs within this same space between the epitaxial layer and the median lamella, or remnants thereof. In specimens in which the median lamella is not developed, it occurs between the epitaxial layer and the opening defined by the ostracod hinge-plane. The essential characteristic of the cellular pattern in the acid-etched internal moulds is that it forms /Hverse-honeycomb-template-like (polygonal/hexagonal) or cyclindrical-cellular-like negative-boxworks (ie., boxworks that are architecturally the opposite of the beeswaxhoneycomb-template structure inasmuch as what is geometrically positive in the honeycomb-template is geometrically negative in the acid-etched ostracod moulds). Typically (but not invariably) the size and shape of the individual (positive/proud) cells (termed "cores" herein; the surrounding inter-core gaps are termed "moats") are uniform within each particular ostracod valve but vary in these attributes from one valve to another, as does the number of cores within the pattern. The cores are made up of the decalcified spongy clayey substrate as described above, and they commonly arise from (ie., are attached to) the epitaxial layer and partly or nearly completely fill the space between it and the median lamella (or its plane of projection). Less commonly can the cores be seen to arise from (ie., be attached to) the median lamella (a circumstance which is probably an artifact of the way in which the nature of the inner structure of the internal moulds presents itself in the acid-residue materials, visual access through the epitaxial layer from without being far less common than visual access from the hinge-plane-opening side of the moulds of the valves). The end of the core which is attached to a substrate is termed "proximal" and its other (commonly unattached or "free-") end is termed distal. The proximal end of the cores is commonly recurved inward (typically across a line of angular inflection) toward the longitudinal axis of the core immediately above the plane of attachment with the substrate, and a low gable-like positive ridge defines the mid-line of the floor of the moat that separates neighbouring cores. The longitudinal (ie., ostracod hinge-plane-transverse) axes of the cores are essentially orthogonal to the carapace hinge-/median-plane, at least in the majority of examples that involve cores of relatively large cross-sectional area; in examples that involve relatively small-sized cores (ie., ones which do not extend very far inward from the epitaxial layer) the hingeplane-transverse axes of such (commonly crowded) cores are likewise quite small, and it is difficult to ascertain if their direction is orthogonal to the plane of the ostracod hinge zone or more closely orthogonal to the curvilinear epitaxial layer. In instances where the entire valve/carapace planimetric area is occupied by the cellular pattern the number of cores present varies inversely with average core-diameter. Most cores in most moulds are equidimensional in cross-sectional (ie., planimetric) shape; less commonly do the honeycomb patterns show cores whose cross-sectional shape is elongated and in these cases all cores tend to show essentially the same degree of elongation as well as a uniform orientation of their axes of elongation. However, the direction of this uniform planimetric core-elongation shows no preferred relationship to the anterior-posterior axis of the valve/carapace itself, being in some examples parallel to that axis, and in other cases oblique or highly oblique to that axis. Largish cores that arise from the epitaxial layer terminate distally at or just short of the median lamella or its plane of projection, but never extend beyond this level; and cores that arise from the median lamella terminate distally in a free-end short of, or just short of, the epitaxial layer. Small cores that arise from the epitaxial layer terminate distally in free-ends well below the ostracod hinge-plane except for those located immediately adjacent to the valve perimeter (ie., hinge and free edges). Cores that have a circular planimetric cross-sectional geometry usually terminate in a subhemisphere. Cores that have a polygonal (usually hexagonal) planimetric crosssectional geometry show various terminations depending upon whether or not their distal ends reach the level of the median lamella (or its plane of projection), viz.: (1) where the distal end terminates fully short of the median lamella, the free-end is a pyramid (commonly with curvilinear edges and apex); (2) where it terminates just short of the median lamella it terminates in a truncated pyramid (commonly with curvilinear edges); (3) where it reaches the level of the median lamella it terminates in a plane-surface coincident with the level of the median 20

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lamella (or the plane of its projection where it is wholly or locally absent) and is fused onto the under-/near-side of the median lamella where the latter feature is present. Examples of each of these types of distal terminations can occur within the same valve, the fused terminations being located around the valve perimeter, inboard of which is an annular zone of cores terminating in truncated pyramids, centric of which are cores that terminate in full pyramids. Other shapes characterize the distal free-ends of cores in some valves but are less common. Except for those cores that are located around the perimeter-margins of the valves (ie., immediately adjacent to the hinge and the free edges), each core in the cellular/honeycomb pattern is separated from its neighbours in the acid-residue moulds by a "moat" whose inter-core width varies directly as a function of the cross-sectional (ie., planimetric) diameter of the cores themselves, and (where measured at the middle of opposed polygonal edges of cores) ranges from 2 to 33 \im with an extreme up to 63 \im. The knowledge that the material that formerly constituted the spaces now defined by the moats is soluble in weak acid suggests that it is calcite, and this conclusion is confirmed by study of thin-section intersections of ostracods that contain the honeycomb pattern (where it is seen to be ferroan-calcite). Cores that are located around the perimeter margins (ie., adjacent to the hinge and free edges) of the valve/carapace commonly have the character of "half-entities" inasmuch as only the inner (more centric) outline/edge of the each core is geometrically defined, the truncated half7part-core so defined thus fusing with the spongy clayey substrate that constitutes the epitaxial layer. Such truncation of the peripheral/marginal cores results from the fact that the moats (which give definition to the outline-geometry of the cores) abut blindly against the epitaxial layer at the valve periphery short of the distance required to complete definition of a whole core. Core-diameter varies in wide limits (13-308 [im; largest diameters measured in planimetrically inequidimensional cores). The observed number of cores per valve ranges from 3 large cores (plus 6 partial peripheral cores) to more than 140 small cores. There is no relationship between the number of cores contained in a valve/carapace and the taxonomic affinity of the ostracod (with probable exceptions of a few valves in which the presence of numerous small and short cores could be associated with equally abundant normal pore canals or their infillings). Otherwise, valves belonging to one and the same species/taxon may contain cores that vary in wide limits with respect to planimetric cross-sectional shape and diameter, as well as length and distribution. The length of cores, although rarely measurable for technical reasons, varies considerably from one ostracod specimen to another. Cores in some valves/carapaces barely rise above the surface of the substrate (usually the epitaxial layer); others span the full distance between the substrate and the median lamella. No cores have been observed that extend beyond the median lamella or, where this is not developed or no longer preserved, beyond its inferred level. Short and small cores within a given ostracod are commonly of equal or very similar size. Long and larger cores on the other hand may be shorter in peripheral parts of the valve than in its central portion if the substrate from which the cores arise comprises the concave surface of the epitaxial layer or an additional thin clay layer superposed upon it. But cores are apparently of equal length where the epitaxial-layer substrate from which they arise is flat and parallel to the median lamella; and they are apparently shorter in central areas than near the periphery if the epitaxial-layer substrate is convex inward. The maximum length of cores that span the entire distance between epitaxial layer and median lamella depends on the depth (width) of the valves/carapaces, and this in turn depends on the taxon and/or on the sex of the mature specimens. An exhaustive analysis of the conceivable origins of the enigmatic calcareous honeycomb pattern in the ostracod internal moulds leads to the elimination of the possibility (on various grounds) that they manifest the skeletons of calcareous coelobionts (ie., cavity-dwelling organisms; cf. KOBLUK & JAMES 1978). Also eliminated is the possibility that they manifest some type of patterned diagenetic (including neomorphic) calcite-crystal-growth seeded epitaxially by the prismatic calcite crystals in the calcareous layer of the outer lamella of the ostracod valves (cf. SORBY 1879, fig. 2; FOLK 1962, figs. 7, 8; FOLK 1965, figs. 6, 7); or that they manifest some type of micro-septarian nodule phenomenon (cf. LINDHOLM 1974). But conversely, the solution of the puzzle (as to what the honeycomb pattern does manifest) becomes immediately clear upon integration of the likely meaning of the spectrum of geometrical attributes of the pattern viewed as a non-organic phenomenon, features such as: (1) the range of different sizes of the individual cells (= cores) from one ostracod to another; (2) the degree of relative uniformity of size and uniformity of shape of the cells/cores within each ostracod specimen; (3) the geometric shapes of the individual cells/cores within the pattern, especially the predominance of polygonal (and especially hexagonal) and cylindrical cross-sectional shapes; (4) the presence at the planimetric edges of the honeycomb patterns of "half-cells" (= truncated cores); (5) the restriction of cells/cores of different planimetric crosssectional shape to different ostracod valves/carapaces (eg., planimetrically-elongated ["flattened"] cells/cores with common axis of elongation/flattening on the one hand versus planimetrically-equidimensional cells/cores on the other); (6) the presence of incurved terminations (involving an angular inflection) at the proximal (attached) ends of the cells/cores and pyramidal/truncated-pyramidal/subhemispherical/fused-flat terminations at the distal ends of the cells/cores; (7) the presence of the low gable-like ridge along the axis of the moats that 21

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separate adjacent cells/cores; and (8) the association of different types of distal terminations of largish prismaticshaped cells/cores of polygonal cross-sectional geometry, and the systematic annular arrangement of these different types of terminations. All these geometrical attributes (and others alluded to herein but not elaborated because of space limitations) are consistent with the properties known of gas-bubble-complexes and the intrinsic surface-tension phenomena and resulting meniscus effects that characterize the physics of gas bubbles in water (cf. BOYS 1959; WARD 1985).

On this basis the honeycomb-like cellular patterns (excluding ones that clearly manifest clay-moulded normal pore canals) are here interpreted to be fossilised trapped taphonomic gas-bubble-complexes that formed within the locally anaerobically-enhanced reducing conditions of closed ostracod carapaces under shallow burial conditions, but evidently at a time subsequent to the syn-burial infiltration of small amounts of detrital clay/physils sufficient to have formed the epitaxial layer and the median lamella. (The presence of the gasbubble-complexes within the carapaces constrains the timing of bubble formation to have occurred subsequent to at least a sufficient depth of burial of the carapaces so as to have prevented them from rising up into the watercolumn and floating away under the influence of their positive buoyancy.) Under such anaerobic conditions ammonia is commonly the gas that is released and concentrated through the decay of organic matter, and its presence has the effect of raising the pH of the associated water and initiating the precipitation of CaC0 (WEEKS 1957, p. 101). The gas was probably generated through decay of organic matter within the ostracod carapaces themselves, probably including the slow progressive or arrested (delayed) decomposition of the carapaces' chitinous linings (chitin being a refractory organic substance that resists organic decay; cf. STANKIEWICZ et al. 1997), and the bubbles were probably rendered physically stable by virtue of the presence of a natural surfactant that would have made them essentially permanent (ie., on a scale of years; cf. BOYS 1959, p. 113). Once the gas-bubbles had formed and stabilised into a complex of approximately equal-sized and equalshaped individuals, and to have evolved into polygonal (especially hexagonal) shapes (eg., see BOYS 1959, fig. 52) as they grew progressively larger through coalescence/fusion of neighbours (as is their natural want to do in order to minimize surface tension), calcium carbonate would then have begun to precipitate within the aqueous bubble walls and its continued precipitation would have led to a progressive thickening of the bubble walls outward from the wall axes, eventually giving rise to a relatively thick, calcified boxwork that fossilised the entire three-dimensional bubble-wall-complex (= calcareous moats in the honeycomb pattern and now-acidremoved former calcareous walls around the geometrically-defined distal free-ends of the bubbles; the proximal ends of the bubbles having been attached to the stratigraphically/spactially upper surface of the inside of the ostracod valve [or the underside of the mediam lamella in the lower valve] thus lacked full wetted-perimeters against that surface and hence were not calcified). This phenomenon has been observed to occur experimentally in the laboratory (though not within cavities in invertebrate skeletons) in a situation where gas-bubble-complexes were produced by anaerobic decay of organic matter in brines that concurrently precipitated calcium carbonate (MCCUNN 1972, see especially p. 154). Once the bubble walls had become mineralised, subsequent escape of the gas from the bubble-voids concurrent with its replacement by connate water, followed by (or concomitant with) the longer-term authigenic growth of an interleaved meshwork of microscopic ferroan-calcite and clay within the former bubble-voids (ie., originally unmineralised bubble centres) then led to the production of the spongy micro-porous cores/cells that manifest the resulting honeycomb patterns in the decalcified internal moulds. 3

Numerous additional points of clarification of the meaning of various geometrical details observed in the calcareous honeycombe patterns could be explored here in the context of the fossil-bubble-complex model but many are beyond the scope of this brief sketch of the model. Explanation of a few such geometrical details must suffice: (1) The gable-like median ridge that defines the mid-line of the floor of the moats on the surface of the epitaxial layer is a meniscus effect and an artifact of surface-tension where the bubble wall divides along a line at the level of attachment of the bubbles to that surface. (2) Arrays of inequidimensional (planimetrically-flattened) cores/cells of polygonal cross-sectional shape with a common axis of elongation/flattening that shows random relationship to the larger-scale symmetry of the ostracod carapace/valve are simply bubbles that have been squashed into a configuration of quasi-horizontal elongation by crowding from below (see BOYS 1959, fig. 52). (3) The truncated half-/part-cores/cells that occur around the perimeter edges of the honeycombe patterns in the ostracod valves are simply the manifestation of half-/part-bubbles such as commonly arise at the edges of gasbubble-complexes (eg., see BOYS 1959, fig. 52) because the physics of gas bubbles prefers (for reasons of minimizing and keeping surface tension uniform throughout the bubble-complex) to sustain bubbles of approximately equal size throughout the whole array rather than to make smaller bubbles at the edges of the confining vessel where the bubble pattern "runs out of room" to keep extending itself in a uniform-bubble-size way (ie., smaller bubbles have higher surface tension than larger bubbles, and are thus inherently unstable). (4) The annular arrangement (described above) of different distal-end terminations on largish cells/cores of polygonal cross-sectional shape in one and the same valve (ie., involving a central area of cores/cells characterised by pyramidal terminations, surrounded by a zone of cores with truncated pyramidal terminations, 22

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surrounded by a zone of cores that terminate in a flat surface fused with the median lamella) simply manifests the three-dimensional geometry of a complex of largish uniform-sized polygonal bubbles that line the underside of the concave-inward epitaxial layer of the upper valve (in a buried carapace whose hinge-line is horizontally disposed), so as to form an arch of bubbles (whose upper, proximal, ends thus do not have a full wettedperimeter against the epitaxial layey), and whose distal (bottom) ends do have full or almost-full aqueous walls except for those bubbles that are located at the margins of the valve; these latter bubbles impinge fully on the median lamella located below them, but bubbles located in the more central areas of the arch have their lower (distal) ends located at progressively higher elevations along the underside of the arch (and above the upper surface of the median lamella or the plane of its projection); thus the bubbles on the outside of the complex do not have a wetted-perimeter (aqueous wall) where they impinge fully on the median lamella, and hence do not calcify at their distal end; this is unlike the bubbles in the more central areas of the arch which do have geometrically-defined aqueous walls at their distal ends — pyramid-shaped in the centre (ie., no impingement on the median lamella) and truncated-pyramid-shaped in the intervening areas where they impinge slightly against the median lamella; thus the clayey cores that subsequently grow to fill the bubble voids of the marginal bubbles extend inwards from the inner surface of the epitaxial layer to fuse onto the median lamella, whereas those that occlude the other more-centrally-located bubble-voids terminate against pyramidal and truncated-pyramidal calcified bubble walls that are later dissolved in the acid-treatment, and thus come be exposed as free-ends. (5) Honeycombe core/cell complexes that arise from the median lamella and have their distal free-ends separated from and facing the epiaxial layer manifest bubble-complexes that were trapped on the underside of the median lamella in a carapace (whose hinge-plane was horizontally disposed in its buried situation) and which therefore lacked full aqueous wetted-perimeters against the median lamella but calcified folly elsewhere (ie., interbubble walls and distal terminations). REFERENCES BLSCHOFF. G.C.O. (1986). Early and Middle Silurian conodonts from midwestern New South Wales Courier

Forschungsinstitut Senckenberg 89: 1-337. BOYS, C.V. (1959). Soap-Bubbles: Their colours and the forces which mold them. Dover Publications, New York. FOLK, R.L. 1962. Petrography and origin of the Silurian Rochester and McKenzie Shales, Morgan County, West Virginia. Journal of Sedimentary Petrology 32: 539-578. FOLK, R.L. 1965. Some aspects of recrystallisation in ancient limestones. In L.C. Pray and R.C. Murray (eds.):

Dolomitisation and Limestone Diagenesis: A Symposium. Society of Economic Paleontologists and Mineralogists Special Publication 13: 14-48. KOBLUK, D.R. & JAMES, N.P. 1978. Cavity-dwelling organisms in Lower Cambrian patch reefs from southern

Labrador. Lethaia 12: 193-218. LlNDHOLM, R.C. 1974. Fabric and chemistry of pore filling calcite in septarian veins: models for limestone cementation. Journal of Sedimentary Petrology 44: 428-440. MCCUNN, H.J. 1972. Calcite and aragonite phenomena precipitated by organic decay in high lime concentrate

brines. Journal of Sedimentary Petrology 42: 150-154. SORBY, H.C. 1879. Anniversary address of the President (Structure and origin of limestones). Proceedings of the Geological Society of London 35: 56-95. STANKIEWICZ, B.A., BRIGGS, D.E.G., EVERSHED, R.P., FLANNERY, M.B. & WUTTKE, M . 1997. Preservation of

chitin in 25-million-year-old fossils. Science 276: 1541-1543. WARD, A. 1985. Experimenting with Surface Tension and Bubbles. Dryad Press, London.

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LATE DEVONIAN - EARLY CARBONIFEROUS CONODONTS FROM SE SARDINIA (ITALY) CARLO CORRADINI SEBASTIANO BARCA and CLAUDIA SPALLETTA 1

Dipartimento di Scienze della Terra (Paleontologia), University di Modena e Reggio Emilia, via University 4,1-41100 Modena, Italy; ccorr@unimo.it Dipartimento di Scienze della Terra, University di Cagliari, via Trentino 51, 1-09127 Cagliari, Italy; barcas@unica.it Dipartimento di Scienze della Terra e Geologico Ambientali, University di Bologna, via Zamboni 67,140127 Bologna, Italy; cspal@geomin.unibo.it The low-grade metamorphic Palaeozoic sequence of SE Sardinia is composed of middle Cambrian-lower Ordovician sandstones, unconformably (Sarrabese unconformity) followed by pre-Caradocian calcalkaline volcanites, upper Ordovician to upper Devonian sandstones, pelites, shales and limestones, and at the top by siliciclastic deposits of the Hercynian "Flysch" (Culm-type). The age of the top unit, lacking fossils, is inferred on the basis of: i) stratigraphic position above uppermost Devonian limestone; ii) presence of large calcareous clasts and exotic blocks yielding Late Devonian conodonts embedded within the siliciclastites (BARCA & SPALLETTA 1985; BARCA 1991; BARCA & OLIVIERI 1992); iii) similarity with other Lower Carboniferous sequences of the circum-Mediterranean area.

The highest part of the Devonian sequence underlying the Culm-type sediments is represented by a thick massive limestone unit yielding ammonoids, mostly climenids, historically known as "Calcari a Clymeniae". These limestones are composed of poorly fossiliferous micrites characterised by a quite rich conodont fauna. Mainly on the basis of conodonts, the age of the unit is attributed to the Famennian (OLIVIERI 1970; CORRADINI 1998a, 1998b). In the Monte Taccu area, two new stratigraphic sections (one on the North slope, the second on the South slope) have been measured and sampled for conodonts through a sequence comprising Famennian limestone to Hercynian "Flysch", near the boundary with the siliciclastics, in order to achieve additional data on the age of the uppermost part of the limestones. The studied samples yielded late Famennian conodonts. The relatively rich conodont fauna is composed of bispathodids, palmatolepids, pseudopolygnathids, siphonodellids, and polygnathids, and indicates the sections range in age from Lower postera to Lower praesulcata zones. In the heavy residues some rare, very well preserved vertebrate microremains (fish teeth) are present. A few samples of the Monte Taccu North section, collected at the very top of the limestone, just under the contact with the siliciclastics, yielded a well preserved, diverse Early Carboniferous conodont fauna. This fauna includes polygnathids, pseudopolygnathids, prothognathodids and siphonodellids, that correspond to the Lower duplicata - sandbergi zones (Tournaisian). This zonal attribution extends the age of the limestone unit up to part of the Early Carboniferous. It should be pointed out that the Devonian-Carboniferous boundary, as well as the Upper praesulcata and the sulcata zones, are apparently missing. The new data testify that calcareous sedimentation in the area continued up to the Early Carboniferous; therefore it is possible to confirm the previously inferred post-Devonian (generically Early Carboniferous) age of the overlying "Sardinian Hercynian Flysch". The beginning of the turbiditic phase of deposition probably occurred within the late Tournaisian, and this may have important new palaeogeographic implications for the timing of Hercynian orogenic movements in Sardinia. REFERENCES BARCA S. 1991. Ph6nom6nes de res6dimentation et flysch hercynien & facifcs Culm dans le "synclinal du Sarabus" (SE de la Sardaigne, Italie). Comptes Rendus de VAcademie des Sciences Paris, 313, 1051-1057. BARCA S. & OLIVIERI R. 1991. Age and source of calcareous rocks into Hercynian flysch-type sediments in

Sarrabus (South-western Sardinia). Atti Soc. Nat. Mat. Modena, 122: 49-66.

BARCA S. & SPALLETTA C. 1985. Nuove osservazioni sul conglomerato di Villasalto (Carbonifero inferioremedio, Sardegna). Giornale di Geologia 46 (1, 1984): 25-32. CORRADINI C. 1998a. Conodonti del Devoniano superiore dei "Calcari a Clymeniae" di Villasalto (Sardegna

Sud-Orientale): Tassonomia e Biostratigrafia. Unpubl. PhD Thesis, University di Modena, 1-139. 24

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1998b. Famennian conodonts from two sections near Villasalto. In: Serpagli (Ed.), Sardinia Guide-book, ECOS VII, Giornale di Geologia, 60, Special Issue, 122-135.

CORRADINI C.

OLIVIERI R. 1970. Conodonti e zonatura del Devoniano superiore e riconoscimento del Carbonifero inferiore nei calcari di Corona Mizziu (Gerrei, Sardegna). Bollettino della Societa Paleontoligica Italiana, 8(2): 63-152.

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SEDIMENTOLOGY AND BIOSTRATIGRAPHY OF A MID-DEVONIAN CARBONATE PLATFORM MARGIN, BROKEN RIVER PROVINCE, NORTH QUEENSLAND JAMES J. DANIELL Centre for Ecostratigraphy and Paleobiology, Deptartment of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Detailed mapping, biostratigraphic and sedimentological investigations of Early to Mid-Devonian (Emsian to mid-Givetian) lithostratigraphic units associated with the "Burgess Submarine Valley", part of the Broken River Group, North Queensland demonstrate that various allochthonous and sediment gravity flow deposits are in fact part of a large and expansive submarine carbonate fan complex. Autochthonous sequences of the Lomandra and Dosey Limestones are separated, in some areas, by a wedge of clastic sediments, herein demonstrated to be part of a primarily conglomeratic facies of the Storm Hill Sandstone, deposited as a submarine fan during a period of rapidly fluctuating sea level. These conglomerates were guided offshore by the Burgess Submarine Valley where they interfinger with the Burgess Formation. The deposition of these conglomerates, in the more distal parts of the basin, occurred as early as patulus zone and possibly as early as serotinus zone or as late as australis zone. Knowledge of the sedimentary dynamics and depositional processes of sediment gravity flows and allochthonous deposits plus their expression in sedimentary sequences is important for both the recognition and interpretation of these deposits in the field. The transition between predominantly autochthonous (Lomandra and Dosey Limestones) to allochthonous sequences (Burgess Formation) plays a defining role in reconstructing the palaeogeography of the Broken River Group. Previous contrasting interpretations of the palaeogeography of the Broken River group of sediments are reviewed and refined in a sedimentary and stratigraphic context. Conodonts were extracted from numerous limestone lithologies including debris flows, turbidites, allochthonous/slide blocks (olistoliths) and in-situ limestones. Data from 10 stratigraphic sections and numerous spot samples are presented. Yields for conodonts were generally low though this is has been remarked upon by previous worker (MAWSON & TALENT 1989). Conodonts extracted from allochthonous limestones often showed diachronism. REFERENCES MAWSON, R. & TALENT, J.A. 1989. Late Emsian-Givetian conodont stratigraphy and biofacies - carbonate slope and offshore shoal to lagoon and nearshore carbonate ramp - Broken River, north Queensland, Australia Courier Forschungsinstitut Senckenberg 117: 205-259.

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PALAEOECOLOGY OF FRASNIAN SPINATRYPINA FROM KERMAN, SOUTH-EAST IRAN MOHAMMAD DASTANPOUR Department of Geology, Shaheed Bahonar University, Kerman, Iran Kerman province is located in south-east central Iran. Devonian strata are the most widely distributed Palaeozoic rocks in Kerman. They crop out in many areas throughout the northern part of the province. Eight stratigraphic sections were studied in detail in this region. Devonian strata consists mainly of limestones interbedded with sandstones and shales. Two reefal carbonate outcrops were sampled along the Harus and Gerik sections situated on the eastern and western limbs of the Hojedk syncline about 75 km north of Kerman. Ten taxa of Rugosa and Tabulate corals were recognized. Disphyllum and Thamnopora are the most common taxa of the Frasnian coral reefs in the Gerik and Harus sections. None of the corals survived into the Famennian. Devonian strata contain abundant brachiopod faunas. Spinatrypina commonly has a restricted distribution being found mainly in the coral reef community. Size, density and biomass of Spinatrypina increases with overall faunal diversity, reaching maximum relative intensity in association with Thamnopora and Disphyllum dominated assemblages. Although many brachiopod taxa existed within Famennian strata, Spinatrypina is not found beyond the reef facies.

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DISTRIBUTION OF EARLY ORDOVICIAN-EARLY SILURIAN CONODONTS IN SILICEOUS BASALT COMPLEXES OF THE SOUTHERN URALS SVETLANA V. DUBININA and ALEXEY V. RYAZANTSEV Geological Institute, Russian Academy of Sciences, Pyzhevsky per., 7,109017 Moscow, Russia The siliceous basalt complex in the northern part of Magnitogorsk Zone in the Southern Urals, known as the Polyakovskaya Formation, is composed of a package of four thrust sheets. These are exposed along the limbs of a strongly faulted and dislocated antiformal feature. Six conodont assemblages were recovered from cherts and cherty shales of the Polyakovskaya Formation in numerous occurrences in the vicinity of Polyakovka village: (1) Mid-Arenig assemblages containing Oepikodus evae LlNDSTROM, Periodon flabellum (LlNDSTROM), Oistodus lanceolatus PANDER, and Protopanderodus rectus (LlNDSTROM); (2) Early Llanvirn assemblages represented by Periodon aculeatus zgierzensis DZIK, Amelia jemtlandica (LOFGREN), Paroistodus horridus (BARNES & POPLAWSKI), and Pygodus sp.; (3) Late Llanvirn faunas comprising Pygodus serra (HADDING), Periodon aculeatus HADDING, Ansella sp., and Baltoniodus sp.; (4) Llandeilo assemblages with Pygodus anserinus LAMONT & LlNDSTROM, Periodon aculeatus HADDING, Protopanderodus varicostatus (SWEET & BERGSTROM), Baltoniodus sp., and Panderodus sp.; (5) Early Caradoc assemblages including Periodon aculeatus HADDING transitional to P. grandis (ETHINGTON), Belodina compressa (BRANSON & MEHL), and Baltoniodus sp.; (6) Late Ordovician (Late Caradoc - Ashgill) faunas composed of Hamarodus brevirameus (WALLISER), Periodon grandis (ETHINGTON), Aphelognathus floweri SWEET, Plectodina aculeatoides SWEET, Protopanderodus liripipus KENNEDY, BARNES & UYENO, Besselodus borealis NOWLAN & MCCRACKEN, Belodina confluens SWEET, Drepanoistodus SUBERECTUS (BRANSON & MEHL), and Ozarkodina sp. The Polyakovskaya Formation does not represent a continuous stratigraphic succession of Ordovician deposits. It represents a series of fragments that have been technically re-assembled into a package of four thrust sheets. In the first thrust sheet (Fig. 1) the fragment of ophiolite association is crowned by cherts with Late Llanvirn Llandeilo conodonts (i.e., 3-4 conodont assemblages). The second sheet is composed of basalts with lenses and beds of grey cherts with Llanvirn conodonts only (i.e., 3 assemblages). In the third sheet, the section is represented by the interval Arenig - Llandeilo on the northern limb of the antiform (i.e., 1-4 assemblages) and up to the Caradoc on the southern limb (i.e., 1-5 assemblages). The fourth sheet is represented by Arenig-Llandeilo faunas (i.e., 1-4 assemblages) on the northern limb only. oX oo < uo

Krasnookhty River (left side)

1.5 km to the SEfrom

^ SE from the 4

Ridge with Z 0V A b z a k o v o v i l , a g e Balbukovka River ^Ua—e ° 552.7 m height (left side) Polyakovka village North foot of a ridge (west side) with 552.7 m height

3 sheet rd

Fig. 1. Correlation of the Ordovician strata in sections of the siliceous-basalt complex (nearby the Polyakovka village) based on conodont succession. 1 - grayish-green, rarely reddish-brown cherts and cherty aleurolite, phthanites, cherty shales; 2 - reddish-brown and red cherts, aleurolites, hematite shales; 3 - grayish-green aphyric basalts, hyaloclastites; 4 - dolerites of a sheeted dyke complex; 5 - serpentinite melange; 6 - conodont localities and their numbers.

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The Ordovician siliceous basalt complex and other members of the ophiolite association probably represent the relict of an accretionary prism where the elements of different zones of the Urals "palaeo-ocean" were technically juxtaposed such that units differ in terms of completeness of stratigraphic sections. Investigation of the siliceous-terrigenous formation, on the right side of the Balbukovka River, probably represent Early Silurian sedimenatation in a forearc basin. In cherts of this formation we have recovered Early Silurian (Late Llandovery) conodont assemblages represented by Apsidognathus tuberculatus WALLISER, Ozarkodina polinclinata (NlCOLL & REXROAD), Ozarkodina pirata UYENO & BARNES. The work is supported by RFFI, grants: N 98 05 64 857 and N 00 05 64 104.

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BIOGEOGRAPHY AND PALAEOECOLOGY IN THE EARLY ORDOVICIAN

OEPIKODUS

RAYMOND L. ETHINGTON , ROBERT S. NICOLL , GODFREY S. NOWLAN and JOHN E. REPETSKI 1

1 2 3 4

Department of Geological Sciences, University of Missouri-Columbia, Columbia, Missouri, USA 65211 Department of Geology, Australian National University, Canberra, ACT 0200, Australia Geological Survey of Canada, 3303 33rd Street N.W., Calgary, Alberta, Canada T2L 2A7 U. S. Geological Survey, 926A National Center, Reston, Virginia, USA 202192-0001

Geographic distribution of the various species of the Early Ordovician (Arenig) conodont genus Oepikodus appears to be strongly controlled by environmental factors. Oepikodus evae appears to be found principally in deeper, cooler waters. It is the only species of the genus found in Sweden. Other species, such as O. communis and O. sp. nov. A, appear to be restricted to warmer or shallower waters. In Australia O. communis and O. sp. nov. A are found in the shallow water cratonic basins (less than 100 m water depth) from which graptolites are generally absent, such as the Canning or Amadeus Basins, and O. evae is restricted to the graptolitic marginal slope facies of Victoria. Occasionally, but rarely, O. evae and O. communis have been reported from the same samples. Examples are the Black Rock Member of the Smithville Formation, NE Arkansas,representing a deepening event lapping onto the edge of southern Laurentia and the upper part of the Metaline Formation, NE Washington, representing a shelfedge depositional environment.

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QUANTITATIVE BIOSTRATIGRAPHIC STUDY OF YANGTZE PLATFORM - WITH THE DESIGNING OF SINOCOR 2.0, A SOFTWARE PROGRAM FOR GRAPHIC CORRELATION FAN JUN-XUAN , CHEN XU , and ZHANG YUAN-DONG 1

Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China

Graphic Correlation, the method for quantitative analysis, can be effectively used in stratigraphic analysis of fossiliferous sections of any geological periods. The first attempt of the software to graphic correlation, the SinoCor 1.0, has been reported during the IGCP410 project Nanjing Symposium (FAN & ZHANG, 1998). It was designed to deal with the large amount of data of sections. Due to the limitation of the functions and capacity of SinoCor 1.0, it is not superior to other similar software. The authors designed the more powerful software, SinoCor 2.0 recently. SinoCor 2.0 is written in Visual Basic programming language and designed for Windows 9.X. The module construction of SinoCor is shown in Fig.l. SinoCor 2.0 adopts interactive graphical interface and thus it can be easily operated. It deals with at least 40 sections and 200 taxa at once. The users can easily expand the capacity through the program menu, which needs quicker computer with more internal memory. SinoCor 2.0 is a free software which can be downloaded from the homepage of the authors, www.osnigp.com. In order to obtain the relatively precise ranges of graptolite species and reconstruct the time scale of Late Ordovician - earliest Silurian in the Yangtze platform, graphic correlation based on the new software seems an important attempt. The present paper studies 9 continuous sections in Hubei and Guizhou provinces. Among them, the Wangjiawan section in Hubei Province, the GSSP candidate section for the Hirnantian Substage (RONG JLA-YU et al. 1999), is considered as the reference section. The GCSS (graptolite composite standard sequence) analysis improves the graptolite biozonation through the Ashgill to Rhuddanian interval significantly. A graptolite macroevolutionary rate of this interval might be demonstrated depending on a more precise time scale. The present work is a contribution to IGCP Project 410

SinoCor 1.0 process

Input of

Revision

Input of

raw data

of data

data file

Plot of 1 Calculate equation data J1 of LOC

Output of Graphic correlation original of sections data

Output of intermediate data

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LATE PRIDOLI, LOCHKOVIAN AND EARLY PRAGIAN CONODONTS FROM THE GAP AREA BETWEEN LARRAS LEE AND EURIMBLA, CENTRAL EASTERN NSW JOHN R. FARRELL Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW. 2109, Australia Sampling for conodonts along three measured sections in the Camelford and Garra Limestones from The Gap area, central eastern NSW, has produced a number of zonal index species - Ozarkodina remscheidensis eosteinhornensis, Icriodus woschmidti, /. postwoschmidti, Amydrotaxis praejohnsoni, Pedavis pesavis and Eognathodus sulcatus eosulcatus. These have enabled dating of the deposition of these two units. Commencement of carbonate sedimentation of the Camelford Limestone occurred in the very latest Pridoli and continued through the eurekaensis Zone and possibly into the delta Zone. In the vicinity of the measured sections the Camelford Limestone is faulted against the Garra Limestone with some loss of section from both units. Approximately 4 km to the north a volcaniclastic unit, the Cuga Burga Volcanics, intervenes between these two carbonate sequences. Samples from the lowest limestone horizons within the Garra Limestone that sit conformably on the volcanics have yielded A. praejohnsoni - delta Zone. Carbonate sedimentation then proceeded through the pesavis Zone and into the very early sulcatus Zone. The Garra Limestone has an unconformable contact with the overlying Late Devonian Catombal Group and both have undergone major folding and erosion so a loss of section at the top of the Garra Limestone is possible. Farther north at Wellington deposition of the Garra Limestone commenced in the pesavis Zone and ceased in the kindlei Zone (WILSON 1989). The lowest horizons of the Camelford Limestone, that contained relevant faunas, are dated as well within the Pridoli with the topmost layers possibly extending into the delta Zone (FARRELL in prep.). This indicates diachronism in the Garra Limestone with younger sediments being deposited in the north (MAWSON et al. 1988) and a reverse of this in the Camelford Limestone with older carbonate sediments occurring in the north. In describing the recovered faunas one new genus, two new species and one new subspecies of Pandorinellina (P. wilsoni, P. ebzeryi, P. optima postoptima) and two new species of Ozarkodina (O. scotti, O. kylieae) have been recorded. REFERENCES MAWSON, R., TALENT, J.A., BEAR, V.C., BENSON, D.S., BROCK, G.A., FARRELL, J.R., HYLAND, K.A., PYEMONT, B.D., SLOAN, T.R., SORENTINO, L., STEWART, M.I., TROTTER, J.A., WILSON, G.A., & SIMPSON,

A.G. 1988. Conodont data in relation to resolution of stage and zonal boundaries for the Devonian of Australia. Canadian Society Pet. Geol., 14(3): 485-527

WILSON, G.A. 1989. Documentation of conodont assemblages across the Lochkovian-Pragian (Early Devonian) boundary at Wellington, central New South Wales, Australia. Courier Forschungsinstitut Senckenberg 117: 117-171.

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HIRNANTIAN CONODONTS FROM THE CARNIC ALPS, AUSTRIA ANNALISA FERRETTI and HANS PETER SCHONLAUB 1

'Dipartimento di Scienze della Terra (Paleontologia) via University 4,1-41100 Modena, Italy Geologische Bundesanstalt, P.O. Box 127 Rasumofskygasse 23, A-1031 Vienna, Austria

The Carnic Alps have long been a key area in Europe for elucidation of Lower Palaeozoic conodont biostratigraphy. WALLISER'S (1964) work on the conodont fauna from the Cellon section still represents a classic reference for much of the Silurian conodont zone succession. SERPAGLI (1967) carefully monographed Ashgill faunas from the "Tonflaserkalk" of Rifugio Nordio and Monte Zermula (northern Italy). FLAJS & SCHONLAUB (1976) reported a similar fauna from the Graywacke Zone of Styria (Austria), whose precise age could only be deduced by comparison with Serpagli's material owing to the absence of M elements of the Late Ordovician agediagnostic Amorphognathus species. Many of the conodont collections available from this region have been described as morphospecies, partially assembled in multi-element taxonomy by SWEET & BERGSTROM (1984). New material was recently provided by BAGNOLI et al (1998) from the Italian side of the Alps. Numerous sections that include Upper Ordovician and Lower Silurian strata are exposed in the Central Carnic Alps; but no continuity has thus far been documented across the Ordovician-Silurian boundary where a significant stratigraphic gap exists. The Late Ordovician is represented by a fossiliferous calcareous horizon with two main lithological types: the massive Wolayer Limestone (up to 18 m thick) composed of parautochthonous bioclasts derived from echinoderm-bryozoan mounds, and the nodular Uggwa Limestone (up to 6 m thick) representing the coeval basinal sediments (DULLO 1992). In some sections, the Uggwa Limestone grades into arenaceous and bioclastic limestones of the Plocken Formation ("Untere Schichten" of old authors; up to 9 m thick). This coincides with the upper part of the "Bereich I" of WALLISER (1964), from which he reported a few conodonts regarded as Early Silurian in age. This formation was later reinterpreted as a regressive sequence of Hirnantian age thanks to the recovery of Hirnantian shelly faunas, mainly brachiopods and trilobites (JAEGER et al. 1975), presumably corresponding to the G. persculptus graptolite biozone (SCHONLAUB 1988). Reinvestigation carried out recently in the Cellon section has provided important new data. Calcareous levels of the Pl5cken Formation above a well-known horizon with representatives of the widespread Hirnantia fauna produced an unexpectedly rich and locally well preserved conodont association. The fauna is composed of more than twenty species with a clear Ordovician aspect. Amorphognathus cf. A. ordovicicus BRANSON & MEHL, 1933 and A. lindstroemi (SERPAGLI 1967) are present. Elements of "Birksfeldia-Dichodella", corresponding to the distinctive North American Gamachian genus Gamachignathus, are also represented. Of significance is the presence of colder regime, high latitude genera (such as Sagittodontina and Istorinus). This preliminary report provides the first detailed definition of the Hirnantian conodont fauna from the North Atlantic Province. Our study also documents abundant conodont assemblages from the Wolayer and Uggwa limestones, which are unequivocally dated as A. ordovicicus Zone thanks to the recovery of the index zone species. The M elements of A. lindstroemi and Amorphognathus sp. were also found. Hamarodus europaeus (SERPAGLI, 1967), Scabbardella altipes (HENNINGSMOEN, 1948), and in some horizons Walliserodus amplissimus (SERPAGLI, 1967), are the most common taxa. These collections are strikingly similar in composition and age to material already described on the Italian side of the Alps and clearly indicate the HDS {Hamarodus europaeus-Dapsilodus mutatusScabbardella altipes) conodont biofacies of SWEET & BERGSTROM (1984). Stronger links with Sardinia (Italy) compared to other typical North Gondwana areas as well as relationships with lower latitudes regions sharing the same conodont biofacies like Avalonia and Baltica (FERRETTI & SERPAGLI 1999) are once more suggested. REFERENCES BAGNOLI, G., FERRETTI, A., SERPAGLI, E. & VAI, G.B. 1998. Late Ordovician conodonts from the Valbertad

Section. In M.C. Perri & C. Spalletta, (eds.), Southern Alps Field trip Guidebook, ECOS VII Giornale di Geologia 60, Special Issue: 138-149.

DULLO, W.-C. 1992. Mikrofazies und Diagenese der oberordovizischen Cystoideen-Kalke (Wolayerkalk) und

ihrer Schuttfazies (Uggwakalk) in den Karnischen Alpen: Jahrbuch der Geologischen Bundesanstalt, 135:

317-333.

FERRETTI, A. & SERPAGLI, E. 1999. Late Ordovician conodont faunas from southern Sardinia, Italy:

biostratigraphic and paleogeographic implications. In E. Serpagli, (edj, Studies on conodonts - Proceedings 33

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of the Seventh European Conodont Symposium: Bollettino della Society Paleontoligica Italiana, 37 (23)(1998): 215-236. FLAJS, G. & SCHONLAUB, H.P. 1976. Die biostratigraphische Gliederung des Altpalaozoikums am Polster bei Eisenerz (Nttrdliche Grauwackenzone, Osterreich): Verhandlungen der Geologischen Bundesantalt., 2: 257303. JAEGER, H., HAVLICEK, V. & SCHONLAUB, H.P. 1975. Biostratigraphie der Ordovizium/Silur-Grenze in den

SUdalpen-Ein Beitrag zur Diskussion um die Hirnantia-Fauna: Verhandlungen der Geologischen Bundesantalt., 4: 271-289.

SCHONLAUB, H.P. 1988. The Ordovician-Silurian boundary in the Carnic Alps of Austria: In L.R.M. Cocks, & R.B. Rickards, (eds.), A Global Analysis of the Ordovician-Silurian Boundary: Bulletin of the British Museum of Natural History (Geology), 43: 107-115. SERPAGLI, E. 1967. I conodonti dell'Ordoviciano superiore (Ashgilliano) delle Alpi Carniche: Bollettino della

Societa Paleontoligica Italiana, 6: 30-111. SWEET, W.G. & BERGSTROM, S.M. 1984. Conodont provinces and biofacies of the Late Ordovician: Special Paper of the Geological Society ofAmerica, 196: 69-87.

O. H.. 1964. Conodonten des Silurs- Abhandlungen des Hessischen Landesamtes fUr Bodenforschung, ,41: 1 -106.

WALLISER,

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THE SUTURE ZONE BETWEEN AVALONIA AND THE ARMORICAN TERRANE ASSEMBLAGE IN C E N T R A L E U R O P E W. F R A N K E

Inst, fttr Geowissenschaften, Justus-Liebig-Universitat, 35 390 Giessen, Germany

This paper reviews the location and tectonic evolution of the suture zone between Avalonia and the Armorican Terrane Assemblage (ATA). All these terranes are characterized by metamorphic and magmatic rocks formed during Neoproterozoic (Cadomian) subduction under the N-Gondwana margin. Distinction between Avalonia and the Armorican fragments is only possible for the early Palaeozoic: the ATA is characterized by relatively steep palaeomagnetic inclinations, traces of the Saharan glaciation, specific faunas and age spectra of detrital minerals. Since these features do not permit to distinguish between individual elements of the ATA, the seaways separating these elements must have remained rather narrow. During early Ordovician through to early Devonian times, the Armorican Terrane Assemblage in Central Europe consists of at least five terranes (FRANKE 1995 and in press; MCKERROW et al in press; TAIT et al in press): A Silurian/Devonian island arc is preserved in southern parts of the Rhenish Massif (MEISL 1995) and structurally deeper parts of the Mid-German Crystalline High:, (ALTENBERGER & BESCH 1993) Armorica sensu stricto (Central-Armorican Massif in France), Franconia (allochthonous fragments at the southern margin of the Rheno-Hercynian belt of S Cornwall and the Rhenish Massif, and structurally higher parts of the Mid-German Crystalline High) Saxo-Thuringia (Saxo-Thuringian Belt), and Bohemia (Tepla-Barrandian Unit). Displaced equivalents of the latter three units are detectable in the W-Sudetes (FRANKE et al 1993; FRANKE & ZELAZNIEWICZ in press).

Remnants of Avalonia are exposed in the various segments of the Rheno-Hercynian foldbelt, i.e., in SW England, the Ardennes, the Rhenish Massif E of the Rhine, the Harz Mts. and in the Moravo-Silesian Belt on the SE flank of the Bohemian orocline. The Avalonia/ATA suture is apparently situated in the boundary region between the Rheno-Hercynian Foldbelt and the Mid-German Crystalline High, but exact location of the suture and reconstruction of the docking history are severely hampered by Devonian through to Early Carboniferous reactivation. Important constraints may be derived from small, technically displaced rock units. Part of these fragments occur in a narrow, greenschistgrade zone at the southern margin of the Rheno-Hercynian Belt ("Northern Phyllite Zone"). In the Taunus Mts. at the southern margin of the Rhenish Massif, this zone contains Silurian through to Early Devonian, arc-related volcanic rocks (MEISL 1995). Further south, the Northern Phyllite Zone contains metapelites with organic-walled microfossils belonging to a cold-water realm, which indicate proximity to Armorica/Gondwana (ANDERLE et al 1995, REITZ et al 1995). Siluro-Devonian arc-related rocks have also been reported from in the Odenwald and Spessart segments of the Mid-German Crystalline High (Altenberger and BESCH 1993, NASIR et al. 1991). Allochthonous fragments at the base of the Giessen-Harz thrust sheet, which was emplaced over the RhenoHercynian par-autochthonous foreland, comprise: early Ordovician quartzites with trilobites of the Neseuretus province and detrital zircons of Armorica/Gondwana affinity. Silurian through to early Emsian limestones and shallow-water clastic sediments, whose faunas show relationships to Bohemia (i.e., Armorica). The faunal and isotopic evidence is reviewed in FRANKE & ONCKEN (1995). New data pertaining to the problem have been published by PLUSQUELLEC & JAHNKE (1999). A similar association of Armorican rocks occurs in a chaotic assemblage in the Lizard complex (SADLER 1974, FRANKE 1982).

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The Armorican fragments structurally underlie Devonian MORB-type metabasalts and their sedimentary cover, which were both derived from the floor of the Rheno-Hercynian ("Lizard-Giessen-Harz") narrow ocean. Since the allochthonous fragments were transported northwestwards at the base of the thrust sheet, their pre-tectonic position must have been on the north shore of the Rhenohercynian ocean. The fragments do not show any evidence of pre-Carboniferous tectonic deformation. From these observations, it is possible to deduce the following sequence of events: during closure of the Rheic ocean between Avalonia and the ATA, an island arc was formed and later accreted to the southern margin of Avalonia. In the Early Emsian, faunas are still different. It appears that the ATA, in Early Devonian time, closely approached Avalonia, but complete docking was not achieved. From the Late Emsian onwards, renewed crustal extension produced the Rhenohercynian narrow ocean. It grossly retraced the boundary between Avalonia and the ATA (i.e., the Rheic ocean), but some ATA fragments were left stranded on the north shore. During the late Devonian and Carboniferous, most of the Rhenohercynian ocean floor and parts of extended Avalonian crust were subducted southwards under the nascent Mid-Germany Crystalline High. Parts of the Siluro-Devonian island arc were underplated under the active margin, and are now exposed in an antiform in the hanging wall (ONCKEN 1997). Fragments of the Rhenohercynian ocean floor and of the distal Avalonian margin were scraped off from the downgoing plate and emplaced, at the base of the Lizard-Giessen-Harz allochthon, on the Rheno-Hercynian foreland (Avalonia). Continuation of the suture in Iberia and in the eastern part of the Bohemian Massif will be discussed. REFERENCES ANDERLE, H.-J., FRANKE, W., & SCHWAB, M . 1995. Rhenohercynian foldbelt: metamorphic units - stratigraphy.

In: D. Dallmeyer, W. Franke, & K. Weber, (eds.), Pre-Permian Geology of Central and Western Europe, Springer, Berlin, 9 9 - 1 0 7 . U. & BESCH, T. 1993. The Bflllstein Odenwald: evidence for pre- to Early Variscan plate convergence in Central European Variscides. Geologische Rundschau, 82: 475-488.

ALTENBERGER,

W. 1982. Variscan Sedimentary Basins on the Continent and relations with south-west England. Proceedings of the Ussher Society, 5: 259-269.

FRANKE,

1995. Rhenohercynian foldbelt: autochthon and nonmetamorphic nappe units - stratigraphy. In: D. Dallmeyer, W. Franke, & K. Weber, (eds.), Pre-Permian Geology of Central and Western Europe, Springer, Berlin, 33-49.

FRANKE, W .

in press. The mid-European segment of the Variscides: tectono-stratigraphic units, terrane boundaries and plate kinematic evolution. In: W. Franke, V. Haak, O. Oncken & D. Tanner, (eds.): Orogenic Processes - Quantification and Modelling in the Variscan Belt. Geol.Soc.London Spec.Publ.

FRANKE, W .

FRANKE, W . & ONCKEN, O. 1995. Zur pradevonischen Geschichte des Rhenohercynischen Beckens. Nova Acta Leopoldina NF 71, 291: 53-72. FRANKE, W. & ZELAZNIEWICZ, A. in press. The eastern termination of the Variscides: terrane correlation and

kinematic evolution. In: W. Franke, V. Haak, O. Oncken & D. Tanner, (eds.): Orogenic Processes Quantification and Modelling in the Variscan Belt Geol.Soc.London Spec.Publ. FRANKE, W . , ZELAZNIEWICZ, A., POREBSKI, S.J. & WAJSPRYCH, B. 1993. Saxothuringian zone in Germany and

Poland: differences and common features. Geologische Rundschau, 82: 583-599. MCKERROW, W . S . , MACNIOCAILL, C . M . , AHLBERG, P.E., CLAYTON, G., CLEAL, C.J. & EAGAR, R . M . C . in

press. The Late Palaeozoic relations between Gondwana and Laurussia. In: W. Franke, V. Haak, O. Oncken

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& D. Tanner, (eds.): Orogenic Processes - Quantification and Modelling in the Variscan Belt Geol.Soc.London Spec.Publ. MEISL, S. 1995. Rhenohercynian foldbelt: Metamorphic units - igneous activity. In: D. Dallmeyer, W. Franke & K. Weber, K. (eds.), Pre-Permian Geology of Central and Western Europe, Springer, Berlin, 118-131. NASIR, S., OKRUSCH, M., KREUZER, H., LENZ, H. & HOHNDORF, A. 1991. Geochronology of the Spessart Crystalline Complex, Mid-German Crystalline Rise. Mineralogy and Petrology, 44: 39-55.

ONCKEN, O. 1997. Transformation of a magmatic arc and orogenic root during the oblique collision and it's consequences for the evolution of the European Variscides (Mid-German Crystalline Rise). Geologische Rundschau, 86: 2-21. PLUSQUELLEC, Y. & JAHNKE, H. 1999. In: R. Feist, J. Talent, J. & A. Daurer, (eds./- North Gondwana: Mid-

Palaeozoic Terranes, Stratigraphy and Biota. Abh. Geol. Bundesanstalt Wien, 1999,4: 435-452. RJEITZ, E., ANDERLE, H.-J. & WINKELMANN, M. 1995. Ein erster Nachweis von Unterordovizium (Arenig) am

Sttdrand des Rheinischen Schiefergebirges im Vordertaunus: Der Bierstadt-Phyllit (Bl. 5915 Wiesbaden). Geologisches Jahrbuch Hessen, 123: 25-38. TAIT, J., SCHATZ, M., BACHTADSE, V. & SOFFEL, H. in press. Palaeomagnetism

and

Palaeozoic

Palaeogeography. In: W. Franke, V. Haak, O. Oncken & D. Tanner, (eds.): Orogenic Processes Quantification and Modelling in the Variscan Belt. Geol.Spec.Publ. SADLER, P. 1974. Trilobites from the Gorran Quartzites, Ordovician of South Cornwall. Palaeontology, 17: 71-

93.

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IN LOVE WITH CONODONTS WOLFGANG FRANKE 1 , MICHAEL DOUBLIER 1 , PETER KONIGSHOF2, ULRICH WIEDERER2 1 2

Institut fttr Geowissenschaften, Giessen, Germany; wolfgang.franke@geolo.uni-giessen.de Forschungsinstitut Senckenberg, Frankfurt, Germany; pkoenigs@sng.uni-frankfurt.de

Conodonts from pelagic limestones in the Devonian of the Montagne Noire (S-France) help to define the worldstratotypes of the Middle/Late Devonian and Devonian/Carboniferous boundaries. Conodonts permit analysis of facies patterns within the Peri-Gondwanan realm. Conodonts conserve oxygen and osmium isotopic ratios acquired in Palaeozoic seawater. Conodonts are also indispensible for studies of the complex tectonic evolution of the Montagne Noire - a classical metamorphic core complex. Emplacement of fold nappes was followed by exhumation of hightemperature/low-pressure gneisses and anatectic granites, which now occupy the "Zone Axiale". Conodont biostratigraphy permits, even in strongly deformed nodular limestones, the identification of stratigraphic younging, which records tectonic facing, and, hence, the sense of tectonic transport. In the Devonian limestones on the south flank of the Zone Axiale, previous studies have reported East-West trending, S-facing folds which have been taken to indicate the sense of nappe thrusting. However, our conodont studies reveal that folds facing North downwards are equally important as folds facing South upwards. Both sets of folds share the same axial plane cleavage and a prominent stretch lineation which parallels the East-West trending fold axes. These relationships, together with some rare 3D-outcrops, indicate that the folds on the S flank of the Zone Axiale do not record southward nappe thrusting, but, instead, represent sheath folds. The sense of shear must parallel the East-West trending fold axes and stretching lineation - but which way? Sheath folds are restricted to the vicinity of the gneissic core of the Zone Axiale, where metamorphism of the meta-sedimentary mantle is highest. Metamorphic grade is documented by the conodont alteration index (CAI) in Late Devonian nodular limestones. Metamorphic zonation cuts across the inverted limb of a major fold nappe and, hence, must post-date formation of the recumbent folds. The sheath folds developed in the high-temperature regime must likewise post-date formation of the inverted limb: they were formed in a stratigraphic sequence which had already been overturned. This observation is vital for the derivation of the sense of shear in the sheath folds. In a XZ-section through the nose of the sheath folds, we observe stratigraphic younging toward the West. If the sheath folds had been formed from a normal stratigraphic sequence, this would imply shearing top to the West. Since, however, the sheath folds were formed in an inverted sequence, the sense of shear must be directed toward the East. This sense of shear corresponds to the tectonic transport observed in the high-grade rocks of the Zone Axiale adjacent to the North. It appears that the northern part of the meta-sedimentary mantle was kinematically coherent with the gneissic core. These relationships will be used to propose a new tectonic model for the core complex of the Montagne Noire: exhumation of hot, low-density gneisses and granites in a dextral pull-apart scenario. For the purpose of this abstract, it is sufficient to underline the importance of conodont studies. Query: is it possible to fall in love with parts of extinct animals?

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FACTORS REGULATING THE DEVELOPMENT OF ELEVATOR RUDIST CONGREGATIONS IN A SANTONIAN CARBONATE PLATFORM SEQUENCE, SOUTHERN CENTRAL PYRENEES EULALIA GILI1 AND PETER W. SKELTON2 1

Departament de Geologia, Universitat Autdnoma de Barcelona, Bellaterra 08193, Spain igpaa@blues.uab.es Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, UK P.W.Skelton@open.ac.uk

Upper Cretaceous carbonate platform deposits show a widespread development of distinctive lenticular to tabular bodies of rock (lithosomes) formed by congregations of upright tubular (elevator) rudist bivalves. Many were generated by slender rudists such as hippuritids, growing constratally - i.e. with the upright to inclined growth of the rudists taking place at a similar rate to sediment accumulation. Hence, only the growing tips of the shells projected (some centimetres) above the sediment surface, and the bulk of the skeletal fabric was embedded in, and supported by, the accumulating interstitial sediment. The matrix, consisting almost entirely of bio-eroded debris, was generated within the local system by biological and physical processes. Here we discuss the factors that regulated the initiation, consolidation and termination of such lithosomes, based on examples in the Santonian of the southern Central Pyrenees. In the study area, rudist congregations developed between phases of sediment influx from neighbouring source areas. For the initiation of settlement, sedimentation rate evidently had to be very low or nil. Frequently, the stopping of continuous sediment fluxes can be related to a relative sea-level rise allowing sequestering of the sediment elsewhere in the platform. The initial rudist growth both provided more hard substrates for rudist settlement, and resulted in the in situ formation of sediment, leading to the embedding and consolidation of the congregation (both positive feedbacks to establishment). Thereafter, rudist density correlated with inferred sediment destabilization at the benthic boundary layer, which in turn affected rudist recruitment. Thus, successful rudist larval settlement declined with increasing numerical density of individuals in the congregation a crucial negative feedback mechanism. The density of the rudist congregations could then have been maintained at more or less the same level through time by this stabilizing process. The history of consolidation and ultimate preservation of an individual congregation appears to be related to the accommodation space made available by relative sea-level rise. Some additional accommodation space could also have been generated by the compaction of underlying sediments, even when sea level remained static. However, the contribution of this last factor was probably small during the development of the congregations themselves. Finally, development of the rudist congregations ceased with progressive shallowing. But since the congregations did not themselves generate significant localized relief, they were not physical obstacles to occasional storm surges and lateral sediment migration and so were prone to reworking and/or burial by allochthonous sediment. A blanket of bioclastic deposits, frequently associated with evidence for shallower conditions, is often seen covering the rudist lithosomes.

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THE PALAEODEPTH AND TEMPERATURE INDICATORS OF TORQUAY, VICTORIA, FROM AHERMATYPIC CORALS MONTAGUE GROVER Deakin University, Rusden Campus, 662 Blackburn Rd, Clayton, Victoria, 3068, Australia Recent depth-temperature distribution of corals can provide a valid basis for estimating the palaeodepth and palaeotemperature conditions for fossilised faunas (WELLS 1967; FlLKORN 1994). It has been deemed reliable for Cenozoic faunas and less reliable for those of Mesozoic age. The assumption is that the extinct, or for that matter, the few extant genera or species, had comparable environmental constraints as the living species or genera. Of the two major forms of coral, the hermatypic, or colonial (reef) corals, are more temperature and depth dependant and more robust. The ahermatypic or solitary corals tend to be more fragile and do not transport well. When complete fossils are found they imply a basically in-situ fauna. By comparing extant coral species with their fossil counterparts assumptions about the depth and temperature of the water can be made. Through systematic studies of the ahermatypic, scleractinian corals of the Jan Juc Marl (Tertiary - Late Oligocene to Miocene - Janjukian), the depositional depth and water temperature can be determined. There has been controversy in the past concerning the depth of the water during sedimentation, and it is only recently when Li et al, (1999) re-assessed the foraminiferal evidence that the palaeodepth has been adjusted to the shallower depths in accordance with coral data. The one thing that foraminiferal data does not show is palaeo water temperature. The corals from the formation can be used to determine the approximate temperature at the time of sedimentation. This study implies that the presence in the fossil record of genera now found only living in warmer waters is evidence that similar higher temperatures existed in Victoria for the duration of the record of these genera. REFERENCES FlLKORN, H.F. 1994. Fossil Scleractinian corals from James Ross Basin, Antarctica. Antarctic Research Series.

65. Washington: American Geophysical Union. 96pp.

Li, Q., Davies, P.J. & McGowran, B. 1999. Foraminiferal sequence biostratigraphy of the Oligo-Miocene Janjukian strata from Torquay, southeastern Australia. Australian Journal ofEarth Sciences, 46(2): 261-273. WELLS, J.W. 1967. Corals as bathometers. Marine Geology 5(5-6): 349-365.

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LATE DEVONIAN CONODONTS FROM DALMEH SECTION, NORTHEASTERN ARDEKAN, CENTRAL IRAN VACHIK HAIRAPETIAN and MEHDI YAZDI Department of Geology, University of Esfahan, Iran Late Devonian conodonts were recovered out of 79 samples from a section in the Dalmeh area, Garigoon Mountains (northeastern Ardekan) using standard acid leaching techniques. Forty three conodont species/subspecies can be recognised from the following genera: Ancyrognathus, Bispathodus, Clydagnathus, Icriodus, Pandorenellina, Pelekysgnathodus, Polygnathus, Mehlina and Siphonodella. The presence of these taxa indicate a time interval from Late Frasnian (Late rhenana to linguiformis zones) to Late Famennian (praesulcata Zone). This is the first identification of the praesulcata Zone from the Late Devonian of Iran, based on recognition of the index species, Siphonodella praesulcata. The palaeoenvironment of the Dalmeh section is considered a shallow water sequence related to polygnathidicriodid biofacies. A possible of deeper water, offshore pelagic biofacies can be interpreted for the praesulcata Zone at the the top of the section, equivalent in setting to the palmatolepid-bispathodid standard biofacies. Additionally palaeoichthyology indicates this section is rich in micro and macrovertebrates specially shark, palaeoniscoid, dipnoan and acanthodian remains typical of the Early and Late Famennian. Undifferentiated dolomites lie on top of the section that are possibly Permian strata. A lateritic bed (mostly bauxites in component) on top of the Late Devonian sediments similar to the Zefreh and Chahriseh areas (NE of Esfahan) is present. This level can be used as key for reconstruction of palaeorelief in those areas, that can be related to the Late Devonian to Permian time interval. This research continues with the process of initial documentation of Late Devonian conodont faunas from the Yazd province, Central Iran. REFERENCES HAIRAPTIAN, V. 2 0 0 0 . Biostratigraphy of Late Devonian sediments in the Dalmeh area Northeastern Ardekan,

based on conodont and vertebrate remains. University of Esfahan, Iran, unpublished M.Sc. thesis, pp. 141.

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DEVONIAN VERTEBRATE BIOSTRATIGRAPHY OF CENTRAL IRAN VACHIK HAIRAPETIAN 1 , MEHDI YAZDI1 and JOHN A. LONG2 1 2

Department of Geology, University of Esfahan, Iran Western Australian Museum, Perth, Australia

Middle to Late Devonian fish faunas are known from different parts of Central Iran. These faunas comprise acanthodians, actinopterygians, chondricthyans. sarcopterygians thelodonts and placoderms which are predominantly marine in many localities. This study presents a survey of previous and current studies on the biostratigraphy of micro and macro vertebrates from ten localities. These localities are from non limestone beds north of Esfahan of hemiansatus to early and middle varcus zones in age (ADHAMIAN 1999, LONG & ADHAMIAN in press); Ab-e-morad, Chanaruh, Hutk and Tangile-ab-Garm- (Ravar), localities in Kerman province of late Givetian to early Frasnian age as noted by P. Janvier and others during several expeditions; Chahrisch area at northeastern Esfahan probably of Early Frasnian and jamieae zone age (HAIRAPETAIN & GHOLAMALIAN 1998, LONG et al in press, LONG & HAIRAPETAIN in press). The Howz-e-Dora and Niaz sections in the Shotori Range, in the vicinity of Tabas yielded Early Frasnian fish horizons beneath the F/F boundary, and crepida Zone fish horizons near the D/C boundary (YAZDI 1999, YAZDI & TURNER in press, YAZDI et al). Fish remains from the Garigeon Mountains in Dalmeh area, north-eastern Ardekan, can be dated in the interval from triangularis to crepidatlli and late postera - early expansa zones (HAIRAPETAIN 2000). The palaeoenvironment of the faunas in these studies, in terms of the polygnathid-icriodontid biofacies, show shallow water conditions prevailed, with the exception of the fish bearing beds at Howz-e-Dorah which represent a deeper water facies. The biostratigraphic positions of the faunas, inferred from associated conodont data, can be used to provide a framework for biogeographic studies. These will increase our data concerning the most important regions related to Middle East terranes, from North Gondwana, during the Devonian time. REFERENCES ADHAMIAN, A. 1999. Biostratigraphy of the Middle Devonian rocks in the Soh area (north of Esfahan, Iran)

based on conodonts.. University of Esfahan, Iran M.Sc. thesis pp.97. HAIRAPETIAN, V. 2000. Biostratigraphy of Late Devonian sediments in The Dalmeh area, northeastern Ardekan based on conodonts and vertebrate remains. University of Esfahan, Iran, unpublished M.Sc. thesis, pp. 141. HAIRAPETIAN, V. & GHOLAMALIAN. H. 1998. First report of Late Devonian fish remains and microvertebrate

fragments in the Chahriseh area northeast of Esfahan, p. 15. In R. Mawson, J. A. Talent, G. Wilson and P. Cockle (eds.). Abstract book, Esfhan Meeting of UNESCO-IGCP project 421, North Gondwanan MidPaleozoic bioevent/biogeography patterns in relation to crustal dynamics, 5-20 December, 1998. LONG, J, A. & ADHAMIAN, A. 2000 (in press). Givetian microvertebrates from Soh area, Iran. Records of

Western Australian Museum. IGCP421 Volume. LONG, J, A., ADHAMIAN, A. & HAIRAPETIAN, V. 2 0 0 0 (in press). 'Middle Frasnian fish remains from Chahriseh

area, Iran. Records of Western Australian Museum. IGCP 421 Volume. LONG, J, A, & HAIRAPETIAN, V. 2 0 0 0 (in press). Famennian microvertebrates from Dalmeh area, Central Iran.

Records of Western Australian Museum, IGCP 421 Volume. YAZDI, M., LONG, J.A. & TURNER, S 2 0 0 0 , (in press), late Devonian and Carboniferous vertebrates from the

Shistu and Sardar Formations of the Shotori Range. Records of Western Australian Museum. IGCP 421 Volume.

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PRELIMINARY ANALYSIS OF LATE DEVONIAN CONODONTS FROM KHUSH-YEILAGH FORMATION (MIGHAN SECTION), EASTERN ALBORZ, IRAN MAHMMOD AHMADZADEH HERAVI1, MEDHDIYAZDI2 and LAEILA KARIMI1 1 2

Geological Survey of Iran, Tehran, Research Centre, Iran Department of Geology, University of Isfahan, Iran

Sixty geological samples were processed by using standard acid-leaching techniques from the Shahrud area (Mighan section). Based on the recovery of conodonts, the age of the Mighan section can be dated as Late Devonian, Frasnian and Famennian stages. This section is rich in micro vertebrates especially sharks teeth that can be of use in the biostratigraphy of the Famennian stage. These remains mostly belong to Phoebodus gothicus, protacrodonts and stethacanthids. The teeth that resemble Phoebodus gothicus, have been reported previously from the Famennian of northwestern Iran (HAMPE 1998) and from central Iran ( L O N G & HAIRAPETIAN 2 0 0 0 , in press). Recovery of ammonoids from the Mighan section that are similar to those from the Mrakib section (Morocco) confirms palaeoenvironmental similarities in Morocco (BECKER et al, 1999) and Iran during the Fammenian. Furthermore, the presence of a sandy unit at the top of the Mighan section can be correlated to the closure of the Famennian in the Mrakib section of Morocco. REFERENCES HAMPE, O . 1998. Remains of Phoebodus from the Upper Devonian (Middle Famennian) of Northwestern Iran

(Chondrichthyes: Elasmobranchii). p. 16, In R. Mawson, J. A., Talent, G. Wilson, and P. Cockle, (eds.). Abstracts book, Esfahan meeting of UNESCO-IGCP Project 421, North Gondwanan mid-Palaeozoic bioevent/biogeography patterns in relation to crustal dynamics, 5-20 December, 1998. LONG, J, A, & HAIRAPETIAN, V. 2000 (in press). Famennian microvertebrates from Dalmeh area, Central Iran.

Records of Western Australian Museum, IGCP 421 Volume. BECKER, R. T., ROCKWINKEL, J., EBBIGHAUSEN, V & HOUSE, M. R. 1999. Jebel Mrakib, Anthi-Atlas (Morocco),

A potential Upper Famennian substages boundary, stratotypes section, In A. Elhasssani and A. Tahiri, Excursion Guidebook, SDS-IGCP Project 421, North Gondwanan mid-Palaeozoic bioevent/biogeography patterns in relation to crustal dynamics, April 23rd-May 1st, 1999.

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SARCOPTERYGIAN FISHES FROM THE HUNTER SILTSTONE (LATE FAMENNIAN) NEAR GRENFELL, NSW, AUSTRALIA ZERINA JOHANSON and ALEXANDER RITCHIE Palaeontology, Australian Museum, 6 College Street, Sydney, NSW 2000, Australia The Hunter Siltstone fauna (Upper Devonian, latest Famennian) comprises a diverse assemblage of placoderm, acanthodian and rhipidistian fishes which are disarticulated, but otherwise well preserved. The biogeographic relationships of this fauna are somewhat unusual for the Upper Devonian of eastern Australia, with the antiarch (placoderm) group Sinolepidoidei described exclusively from Grenfell and the North and South China terranes. This relationship has been used previously to assess position and timing of rifting of Asian terranes from the northern margins of Gondwana. Rhipidistian fishes (Sarcopterygii, Osteichthyes) are well represented in the Hunter Siltstone. They include a tooth-plated lungfish, two tetrapodomorphs and three dipnomorphs (including two porolepiforms), and a phylogenetically basal form possessing a combination of tetrapodomorph and dipnomorph characters. Sarcopterygians from North and South China terranes are rare, but lungfish and other rhipidistian scales have been described from the South China terrane (Wutung Group, near Nanjing), in association with two sinolepid species. However, these scales do not show strong similarity to the Hunter Siltstone taxa. Other Late Devonian localities in NSW show stronger faunal similarity to Euramerican localities; the widely distributed Late Devonian porolepiform Holoptychius occurs in certain of these and in the Hunter Siltstone, but thus far appears absent from sinolepid-bearing units on the North and South China terranes.

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SIGNIFICANCE OF A PALEOISLAND AND RELATED ROCKY COASTLINE FROM THE UPPER SILURIAN (LUDLOW) OF THE SINO-KOREAN PLATE MARKES E. JOHNSON1 and JIA-YU RONG2 1 2

Geosciences Dept., Williams College, Williamstown, MA 01267, USA Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing 21008, China

All ancient rocky shores are represented in the geologic record by unconformities of one kind or another. Burial of substantial palaeotopography results in physical breaks that may be used to quantify sea-level changes and sort out other large-scale palaeogeographic vagaries. Preliminary results are reported, herein, regarding the physical geology of an Upper Silurian rocky island and related coastline from Inner Mongolia on the continental shelf of the Sino-Korean Plate (North China Block). Ordovician basalt, diorite, and granodiorite comprise the principal igneous bedrock in a region of north-central Inner Mongolia situated 140-180 km northwest of the provincial capital of Hohhot (China). The Upper Silurian Xibiehe Formation is widely distributed throughout the area above and lateral to the igneous basement rocks. Diverse brachiopod, coral, and stromatoporoid faunas generally place the formation within the Ludlow Series (Li et al, 1983). The detailed palaeontological results of this study are reported elsewhere. A critical key to the Silurian bathymetry and geography of the Sino-Korean platform is embodied in a small palaeoisland located near Bater Obo about 50 km south of the Chinese-Mongolian border. The island is composed of resistant diorite bedrock with an oblong shape that measures 610 m x 200 m. Limestone strata conforming to the Xibiebe Formation surround the island and dip away from the igneous core in a radial pattern at fairly steep angles. The present geographic orientation of the island follows a bearing of N55°E. Silurian strata on the broad northwest and southeast flanks of the island dip off in opposite directions at complimentary angles up to 50°. Strata on the constricted east and west flanks of the island dip off in opposite directions at lesser angles up to 25°. Although the dip slopes are probably too extreme to be fully snysedimentary as carbonate ramps, retention of a balanced symmetrical arrangement indicates that the island and its associated strata underwent no appreciable amount of tectonic tilting in post-Silurian time. The exposed minimum topographic relief of the igneous core is 30 m. Silurian strata on the southeast flank of the island have been stripped away except for a relatively thin cover. In contrast, strata on the northwest flank exhibit development of a thick escarpment capped by a carbonate mud mound that towers above the exhumed palaeoisland. Restoration of the stratigraphic canopy over the island indicates that a minimum rise of 30 m in sea level was required to completely bury the island. This transgression may be related to prominent eustatic highstands in sea level during the Early or Late Ludlow. Differential erosion on the opposite principal flanks of the palaeoisland is directly related to their contrasting lithofacies. The softer southeast flank is composed primarily of silty limestone in which large stromatoporoids are imbedded, many directly on the unconformity surface. On the opposite flank, a diorite conglomerate consisting of rounded to angular boulders and cobbles 2-3 m in thickness is succeeded by dense limestone up to 5 m in thickness. Encrusting stromatoporoids are not present on the northwest side of the island. The contrasting facies indicate that the northwest side of the island was subject to more vigorous wave activity than the southeast side. A simple dichotomy of exposed windward versus sheltered leeward environments is strongly implicated. Islands are small, highly constrained components of much larger palaeogeographic entities that often reveal precise information about climatic interactions with marine and atmospheric circulation patterns. We entertain the interpretation that the Silurian island near Bater Obo was formerly located in the low-latitude trade winds of the Northern Hemisphere. If so prevailing winds and waves swept against the island from the northeast to the southwest in response to a powerful high-pressure system over the equator that was operational through most of the year. Our explanation is corroborated on a wider geographic base by analysis of related unconformities located about 30 km further to the south, where a linear Silurian rocky coastline extends for a distance of more than 10 km from the Gushan area to Baorhantu. With an approximate present strike of N60° E, the orientation of this coastline is roughly parallel to that of the palaeoisland. The southwestern half of the shore consists of granodiorite, but the immediately adjacent northeastern part is composed of more resistant basalt (assigned to the Baorhantu Formation). During our investigation of this shoreline, we were surprised to find that one of the lithofacies in direct contact with the basaltic coast is relatively coarse siliciclastic sandstone. We believe the sandstone was derived from the granodiorite of the Gushan area and was transported by a long-shore current driven by oblique winds to the Baorhantu area. The directionality of this interpretation is confirmed by low-angle cross beds in the sandstone facies.

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Based on these relationships, the greater North China Block (and perhaps the entire Sino-Korean Plate) should be rotated at least 90° clockwise from its present position in order to approximate its original Silurian orientation under a prevailing atmospheric system associated with northeasterly trade winds. Different authors have interpreted the global position of the Sino-Korean Plate during the Silurian Period in different ways, but most follow SCOTESE & MCKERROW (1990), showing the Korean Peninsula in the same orientation as today, but only slightly more to the south. None of the published scenarios makes an accommodation for prevailing winds that satisfies our physical data. REFERENCES Li W.G., RONG J.Y. & DONG D.Y. (eds.). 1983. Silurian and Devonian Rocks and Faunas of the Bateaobao Area in Darhan mumingan Joint Banner, Inner Mongolia. People's Publishing House of Inner Mongolia, Hohhot, 46 p. (in Chinese with English abstracts) SCOTESE, C.R. & MCKERROW, W.S. 1990. Revised world maps and introduction. In W.S. McKerrow and C.R. Scotese (eds.), Palaeozoic Palaeogeography and Biogeography. Geological Society of London, Memoir 12, p. 21.

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LATEST ORDOVICIAN-EARLY SILURIAN CONODONT BIOSTRATIGRAPHY IN THE CAPE PHILLIPS FORMATION, ARCTIC CANADA DAVID M.S. JOWETT and CHRIS R. BARNES University of Victoria, School of Earth and Ocean Sciences, P.O. Box 3055,Victoria, British Columbia V8W 3P6, Canada, d iowett@u vic.ca, crbarnes@uvic.ca An unprecedented biostratigraphic opportunity exists in the Canadian Arctic Islands to refine the latest Ordovician-Early Silurian conodont biostratigraphy. The thick passive-to-convergent Franklinian succession contains a record of sedimentation that began in latest Proterozoic time and contains a thick sequence of shelf and slope deposits whose deposition was terminated in the Devonian as a result of the Ellesmerian Orogeny. The Cape Phillips Formation represents the slope equivalent facies of the latest Ordovician to Devonian reef-rimmed shelf-to-basin transition that formed through a pronounced back-stepping event in Late Ordovician time. This flooding event, in combination with the Early Devonian Boothia Uplift, resulted in the advantageous deposition of a spectacular graptolitic shale and carbonate sequence over the drowned Ordovician shelf in the central high Arctic which preserves significant conodont yields of exceptional quality (CAI<2). The acuminatus and nathani Zones are well represented, and are separated by a palaeokarst surface. Admixture of Ordovician and Silurian faunas cannot be confirmed. Oulodus? nathani, the nominate species, along with Oulodus kentuckyensis, Dapsilodus obliquicostatus, Distomodus kentuckyensis, Ozarkodina hassi, O. oldhamensis, and Decoriconus fragilis occur immediately above the Ordovician-Silurian boundary. Post-nathani Zone faunas are dominated by an apparent deep-water association of Aspelundia, Walliserodus, and Dapsilodus obliquicostatus. The Aspelundia-Dapsilodus association is a typical Llandovery offshore fauna, and appears earlier in basinal sequences than on continental shelves. Aspelundia expansa is common until just prior to the base of the celloni Zone. The celloni and amorphognathoides zones preserve a rich diversity and abundance of late Llandovery conodonts. In the lower Telychian an association of Aspelundia fluegeli and the closely related Aspelundia capenis/Pandorinellina plana species appear and dominate the fauna until their relatively abrupt disappearance within l-2m of the base of the insectus graptolite Zone (a brief interval immediately before the base of the Wenlock). This may mark the transition from the Lower to Upper Pseudooneotodus bicornis zones of JEPPSSON (1997), the second datum plane of the Ireviken Event which details the largest Silurian conodont turnover. Walliserodus also appears to have a lineage that shadows that of Aspelundia through the Llandovery. After the disappearance of Walliserodus in the fastigatus graptolite Zone, Walliserodus reappears in early post-nathani time and is dominant throughout the remainder of the Rhuddanian and the Aeronian stages, but disappears in prQ-celloni strata in the earliest Telychian. After a short interval, Walliserodus cf. W. sancticlairi appears and is dominant until just prior to the Llandovery/Wenlock boundary. Dapsilodus obliquicostatus appears at the Ordovician/Silurian boundary, and is found in low abundance until its last occurrence in the Llandovery in the lowermost Telychian. It reappears and dominates the lower Sheinwoodian in association with Kockelella ranuliformis, Ozarkodina e. excavata, and a new, peculiar conodont genus. This occurs after the last appearance of Pterospathodus pennatus procerus, and hence is interpreted as sometime after datum plane six of the Ireviken event. Although sparse, key later Wenlock species have been identified, including Kockellapatula, K. absidata, and Ozarkodina conlfuens. The conodont data from the Cape Phillips Formation details the faunal events in the slope environment across the second greatest mass extinction boundary (the Ordovician/Silurian), the Llandovery recovery and radiation, and the Llandovery/Wenlock turnover. The refined biostratigraphic data allow interpretations of the control of fauna by sea-level change and/or changes in ocean and climate states.

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BIOSTRATIGRAHY AND PALAEOECOLOGY OF SPINATRYPINA HORIZON IN CENTRAL IRAN (ESFAHAN AND KERMAN REGIONS) MOHAMMAD R. KEBRIA-EE Department Of Geology, Faculty Of Sciences, Esfahan University, Esfahan, Iran, Kerbria-ee@ScLui.ac.ir

The sequences in the age of Late Devonian (Frasnian) in the Central Iran (specially Esfahan and Kerman regions) are wide spread. The rocks consist of: limestones, marly limestone, sandstone and dolomite. This sedimentary series in Esfahan (Zefreh and Chariseh areas) and Kerman regions (Hootk, Houjedk, Gerik, Goudechah, Shams-Abad and Baghin areas) have one or two biostromes. Most fauna in these biostroms are corals (belonging to Rugosa and Tabulata families), sponges, algae etc. There are a few marly limestone beds near the biostrom like horizon in which can be found many brachiopoda. Most of the brachiopoda faunas are related to the Spinatrypina genus. Spiratrypina genus in these regions has four species which consists of, Spinatrypina robusta, S. marisul, S. bodini and S. chitralensis. These species are associated with other brachiopods Cyrtospirifer, Cyrtina and Rhynchonellida orders such as Cyphoterorhynchus, C. koraghensis, C. koraghensis interpsitus and Rhipidiorhynchus elbozensis, they make an assemblage biozone. In addition recovered conodont species from the marly limestone in the Esfahan region (Zefreh and Cherish areas) the following species have been identified; Polygnathus aspelundi, P. pacificus, P. aequails, P. sp., Icriodus symmetricus, I. sp. All species the above mentioned fauna show that the marly limestone horizon is no older than Hassi Zone in age (YAZDI 1999) and also it seems Spinatrypina genus prefer reefal environment to other environments.

REFERENCES YAZDI, M. 1999. Documentation of Late Devonian - Carboniferous conodont faunas from the Shotori Range,

Eastern Iran. /w-Mawson, R.,. Talent, J., Wilson, G. and Cockle, P. (eds.): Abstract book, Peshawar Meeting of UNESCO- IGCP 421. .31-32.

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GEOCHEMISTRY, ACRITARCHS AND GRAPTOLITES OF THE LUNDGRENI EVENT OF THE EAST EUROPEAN PLATFORM A. KOZLOWSKA-DAWIDZIUK , E. POREBSKA , and M. MASIAK 1

1 2 3

Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, PL-00-818 Warszawa, Poland Jagiellonian University, Institute of Geological Sciences, Oleandry 2a, PL-30-063 Krakow, Poland Institute of Geological Sciences, Polish Academy of Sciences, Twarda 51/55, PL-00-818 Warszawa Poland

The lundgreni Event in the Polish part of the East European Platform (Baltica), earlier recognised in detailed studies of the graptolite sequence, is here analysed for the first time in terms of 8 C o , 8 C b a t c > and 8 0 isotopic record. Changes of isotope frequencies are synchronous and indicate similar and simultaneous amplitudes of fluctuations. These data are correlated for the first time with stratigraphic changes in the primary palaeoproductivity recorded in the acritarch succession, together with the biomarker distribution of organic matter. l 3

car

The graptolite extinction at the end of the lundgreni Biozone is correlated with a rapid increase of 5 C M (2%O), 8 C carbonate (0.7%o) and 8 0 (1.5 %o), and a very small decrease in total organic carbon and CaC0 . Simultaneously, the frequency of acritarchs increases with the domination of leiospheres. Biomarker distributions are such as those expected for marine organic matter, and are characterised by a smooth n-alkane profile, with low abundance of C o+ members. This may suggest that the positive anomalies in the isotope composition of organic carbon, carbonate carbon and oxygen do not represent a distinctive change in the nature of palaeoproductivity. 1 3

The first phase of the post-extinction crisis, with no graptolites preserved, is correlated with the largest increase of isotope anomalies for 5 C (2.8%o), 8 C „ a t c 0 % ° ) and S 0 (1.2%o). There are no changes in the acritarch frequency and diversity, nor are there any positive indicators of palaeoproduction intensity. Thus, the primary productivity in this phase of lundgreni-Event are the same as those at the end of the lundgreni Biozone. However, analysis of biomolecular organic matter (with the predominance of C hopane over C 9 regular sterane) points to more dysoxic conditions during the deposition of organic matter. It might hence be concluded that the marked anomaly after lundgreni extinction was not caused by a change in nature of primary productivity. 1 3

O M

1 8

carbo

The second phase of the post-extinction crisis, with the occurrence of the opportunistic graptolites Pristiograptus parvus and Gothograptus nassa, is interpreted as a return to more negative isotopic values, characteristic of the pre-crisis phase. This differs from other regions like Sudety (southern Rheic ocean), and Masyw Malopolski (Gondwanan microcontinent), where the positive anomaly continues. Biomolecular markers show algal type of kerogen only, deposited in oxidized conditions on the sea floor. This interval is characterised by a change in acritarch flora, which becomes more frequent, but less diverse, and dominated by Leiofusa spp. This may reflect a slight enrichment of nutrients in the photic zone that enabled the renewed colonization by graptolite plankton. The end of the second phase of the post-extinction crisis and the beginning of the recovery phase is recorded by the next positive anomaly of 8 C (1.7%o), 8 C t e (1.2%o) and 8 0 (1.2%o). The anomalies of organic carbon and oxygen are smaller, and comparable to the anomalies at the beginning of the crisis, whereas the anomaly of inorganic carbon is larger. The acritarch assemblage is more diversified, comprising long-ranging, cosmopolitan taxa, as well as some new forms, and lesser numbers of Leiofusa spp. In general, this assemblage is similar to those from the top of the lundgreni Biozone. The biomarkers exclusively document algal kerogen deposited in a well-oxygenated water column. 1 3

O M

1 3

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The lundgreni Event is thus associated with two positive anomalies in organic and inorganic carbon isotopes, as well as in oxygen isotopes. These anomalies are in-phase, and their stratigraphic position is precisely known with respect to successive phases of the post-lundgreni crisis. The first anomaly is correlated with the main phase of the post-extinction crisis, and the second one falls at the beginning of the recovery phase. These anomalies are not related to any major changes in the photic zone. According to the pyrolitic and biomarker analyses of the organic matter in successive crisis phases, the producers were of algal origin, and biochemically unchangeable. The activity of primary producers was almost stable during the lundgreni Event. There is evidence of only a small increase in oligotrophication of the photic zone after extinction and during the postextinction crisis.

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The isotopic record of the lundgreni Event from the Bartoszyce borehole in the East European Platform differs from that in the Sudety (SW Poland) and Masyw Matopolski (SE Poland). In the latter regions there is one positive anomaly in the parvus/nassa interval. The Bartoszyce-borehole isotope record seems to be more precise than that of other regions characterised by condensed sequences, although some differences may also be due to geographical variations. More studies are necessary in searching for the causes of, and formulating a model for, the lundgreni Event.

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FAUNAL CHANGEOVER AND DIVERSITY TRENDS ON THE ARENIGIAN/LLANVIRNIAN BOUNDARY IN THE BOHEMIAN ORDOVICIAN PETR KRAFT1 and JAROSLAV KRAFT2 1

Charles University Prague, Faculty of Sciences, Institute of Geology and Palaeontology, Albertov 6, CZ128 43 Prague 2, Czech Republic, kraft@natur.cuni.cz West Bohemian Museum PIzen, Kopeckeho sady, CZ-301 36, Plzen, Czech Republic, ikraft@volnv.cz

In 1 9 9 0 - 1 9 9 1 , during the construction of a highway west of Rokycany, the most complete section of the Arenigian/Llanvirnian boundary interval in the Prague Basin (Czech Republic) was uncovered . This section is situated in the area of the classical locality at DrahouS and it was documented in detail by the present authors; preliminary results of macropalaeontological and stratigraphical investigations have been published (KRAFT & KRAFT 1993). Some new dendroid graptolites were described by KRAFT et al. ( 1 9 9 3 ) , whereas ichnofossils were studied by MIKULAS ( 1 9 9 4 ) . The evaluation of qualitative data (stratigraphical distribution) made it possible to distinguish the succession of periods characterized by typical animal groups and their diversity (Fig.l).

Period 7

Period 6

Period 5

| i 9n9nOnO A

Period 4

I u i

Period 3 Period 2

Period 1

Fig. 1. Measured section at Drahous with stratigraphical ranges of essential taxa. Patterns: 1 (horizontal hatch) • shales; 2 (accents circumflex) - volcanoclastic rocks; 3 (circles) - oolitic iron ores. Period 1. The uppermost part of the shales of the Klabava Formation (Arenigian). In the fauna, graptolites and inarticulate brachiopods prevail. Among graptolites dendroids are very common. Clusters of sponge spicules are locally abundant on the bedding planes. The remains of phyllocarid crustacens are rare. The diversity is stable and corresponds to other localities in the western part of the Prague Basin. Period 2. The interval of volcanoclastic rocks (tuffitic shales and tuffs) belonging to the top of the Klabava Formation (Arenigian). In contrast to period 1, fossils are represented excusively by animal groups with organophosphatic shells, only inarticulate brachiopods can be identified. The absence of fossils with organic shells is probably a secondary taphonomic feature. Period 3. Iron ores in the basal portion of the Sarka Formation (Arenigian). No fossils are known from this interval with the exception of one specimen of the index species Corymbograptus retroflexus found 3 cm below the top of the iron ore layer.

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Period 4. Shales in the lowermost part of the Sarka Formation (Arenigian). At a higher taxonomic level the fauna is very similar to that of period 1. On the species level, the fauna underwent an important changeover. New species of graptolites and inarticulate brachiopods appeared and an abundance and diversity of dendroids sharply decreased. There is a difference in the abundance of phyllocarid crustaceans; the number of specimens rapidly increased. Moreover, new elements (cephalopods and trilobites) appeared, but they are very rare. Period 5. Shales in the lower part of the Sarka Formation (Llanvjrnian). The character of the fauna corresponds to that of period 4, but its diversity is moderately increased. It is enriched by hyolithids, ostracods and new species of graptolites including Llanvirnian pendent didymograptids. Cephalopods and trilobites are more abundant. Period 6. Shales in the lower part of the Sarka Formation (Llanvirnian). The short period of decreasing diversity is marked by the successive disappearance of cephalopods, hyolithids, ostracods, trilobites and even some species of graptolites, including pendent didymograptids. Period 7. Shales in the lower and middle part of the Sarka Formation (Llanvirnian). This period begins with the abrupt appearance of a highly diversified fauna. Only graptolites are strongly restricted. Among them Corymbograptus retroflexus and Undulograptus novaki prevail through the whole interval, Didymograptus spinulosus reappears and is abundant higher in the section following a substantial absence. The described changeover is one of the most marked faunal events in the Bohemian Ordovician. REFERENCES KRAFT, J., KRAFT, P.(1993. The Arenig/Llanvirn boundary (Ordovician) in the Prague Basin (Bohemia). Journal

of the Czech Geolological Society, 38 (3-4): 189-192. KRAFT, J., KRAFT, P. & SEIDL, R.(1993. New dendroid graptolites from the Lower Ordovician of Bohemia). Journal of the Czech Geolological Society, 38 (1-2): 89-94. MIKULAS, R. 1994. Trace fossils at the Arenig-Llanvirn boundary (Ordovician, Czech Republic). Journal of the Czech Geolological Society, 3 9 (2): 2 0 5 - 2 1 2 .

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THE AGSO PALAEONTOLOGICAL COLLECTIONS JOHN R. LAURIE Australian Geological Survey Organisation, GPO Box 387 Canberra, ACT 2601, Australia The AGSO fossil collections are large and are physically divided into two collections. The first and smallest, but in some ways most important, is the Commonwealth Palaeontological Collection (CPC), which is a specimen based collection comprising type, illustrated, or otherwise published material. Currently this collection contains over 35,000 specimens ranging from 3,500 million year old Archaean microfossils to more recent palynomorphs, forams, nannofossils, conodonts, brachiopods, trilobites, bivalves, fish, birds, mammals and many other groups. This collection is currently growing at over 500 specimens per annum and resides in a compactus unit and several slide and other cabinets in the basement of the main AGSO building at Symonston. The CPC collection data is currently stored on an ORACLE database. This database is outdated and is now in the initial stages of being updated and integrated with the other databases throughout the organisation. Furthermore, it is planned that this database will be accessible via the internet and will eventually contain images of each specimen in the collection. The second, and by far the largest, is variously termed the 'bulk' or 'field' collections. This collection is a sample based collection and occupies about 60% of the high-rise shelving in the palaeo/rock store, in the AGSO support building at Symonston. This 60% comprises about 6,354 drawers, each 85cm x 50cm x 9cm, as well as 1,120 deeper shelves for larger specimens and assorted boxed collections. This high-rise storage extends up to about 10m above floor level on the high side of the building and about 6.5 m on the low side. The collection is accessed by a stockpicker. The 'bulk' collection data is currently partly stored on an EXCEL spreadsheet, which contains the drawer number, field sample number, and commonly the collector, geological province and state. This currently runs to about 33,000 entries. Unfortunately, all the locality information is either in publications, field notebooks, on airphotographs or in a record card system which dates from the 1950s and runs to several metres thick. It is hoped that a database for this collection will be developed, but it is an enormous task and will take much effort. The material in the 'bulk' collection comes from all over the continent, from offshore territories, including Antarctica, as well as from Papua-New Guinea, and is from outcrop, drillcore (both onshore and offshore), deep sea dredge samples etc. A large proportion of the material in this collection was originally obtained during the time when AGSO (then BMR) was involved in regional mapping. Samples would be brought back from the field, a quick analysis of the age (eg. Middle Cambrian) and palaeoenvironment (eg. marine, fluvial etc.) given and the samples put into storage. Only some of these collections were later worked on in more detail and the results published. Some of the later work on this material formed the basis of the biostratigraphic framework for the continent. The 'bulk' collections are an enormous repository of information, only part of which has been extracted. It is in the interests of the nation that this information is extracted and made available.

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MIDDLE CAMBRIAN BIOSTRATIGRAPHY OF THE NORTHERN TERRITORY: PRELIMINARY RESULTS

SOUTHERN

GEORGINA

BASIN,

JOHN R. LAURIE Australian Geological Survey Organisation, GPO Box 387 Canberra, ACT 2601, Australia A study, as part of a joint project with the Northern Territory Geological Survey, on the petroleum prospectivity of the Cambrian of the southern part of the Georgina Basin was undertaken. It was based on the analysis of coreholes as outcrop is generally poor. These included: NTGS Hue 1, Hue 2, Elk 3, 99/1; BMR Hay River 11; Pacific Oil & Gas Baldwin 1, Ross 1, Hacking 1, Owen 2, Maclntyre 1; MIM BHD4, BHD9. In these wells the Middle Cambrian succession mostly lies between archaeocyathid-bearing Lower Cambrian dolostones (Errarra Formation & Red Heart Dolomite) and Upper Cambrian limestones and dolostones of the Arrinthrunga Formation. In the western part of the area (Huckitta sheet area), the fossiliferous Middle Cambrian succession is mostly referred to the Arthur Creek Formation, while to the east (S Tobermory and N Hay River sheet areas) it is referred to the Hay River Formation and the overlying Marqua Formation. To the northeast of this (NE Tobermory sheet area) the succession is referred to the Thorntonia Limestone, Georgina Limestone and Steamboat Sandstone. Detailed sampling of all of the above wells was undertaken by Dr P. Kruse (NTGS) and the author during 1999. Preliminary analyses of each corehole was undertaken and certain coreholes selected for more detailed preparation and analysis. This is still under way. The fossiliferous succession in NTGS Elk 3 (lowest 114m of Arthur Creek Formation) contains a succession of agnostid faunas near the bottom of the formation which begins (100-103m) with an assemblage limited to Itagnostus elkedraensis, overlain by an assemblage containing /. elkedraensis and Pentagnostus anabarensis (99-100m). Above this /. elkedraensis continues but it is associated with Pentagnostus praecurrens (69-84m). This in turn is overlain by an assemblage comprising Acadagnostus sp., Pentagnostus sp. nov. (57-65m). From 55-57m, Acadagnostus sp. is the only agnostid found and above this is a mostly barren interval (55-20m), but in the uppermost parts (6-20m) the polymerid Xystridura sp. is ubiquitous. A similar succession of agnostid assemblages also occurs near the base of the Arthur Creek Formation in Pacific Oil & Gas Baldwin 1 (870-882m). From 814-870m is a barren interval followed by several horizons containing Xystridura sp. commonly associated with a pagetiid species (664-810m). Above this, at 653-659m is an unusual pustulose ptychoparioid. An unexpected discovery is the occurrence (at 603m) of Xystridura sp. with Onymagnostus angulatus, an agnostid known only from the late Floran to late Undillan. Xystridura sp. has not previously been recorded younger than late Templetonian in Australia. A similar succession is also present in Pacific Oil & Gas Macintyre 1. In one corehole (MIM BHD 9) an undoubted Redlichia sp. is found some distance above agnostids of the Itagnostus elkedraensis assemblage interspersed with Xystridura sp.. Given that Redlichia supposedly indicates and Ordian age in this part of the continent, this occurrence poses a conundrum. The presence of a succession of agnostid assemblages apparently older than the late Templetonian Triplagnostus gibbus Zone will require revisions of the Australian Middle Cambrian biostratigraphic scheme. The presence of Xystridura sp. apparently younger than Templetonian T. gibbus Zone will impact on the rather simplistic use of that genus as a Templetonian or older index. The presence of Redlichia sp. above agnostids {Itagnostus elkedraensis) of suspected early Templetonian age indicates that the more recent interpretation of the Redlichia biofacies and the Xystridura biofacies as partial temporal equivalents may be closer to the truth than the previous successional interpretation.

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THE UPPER WENLOCK GRAPTOLITE EXTINCTION (LUNDGRENI EXTINCTION EVENT): PERSPECTIVES FROM ARCTIC CANADA A.C. LENZ1 and A. KOZLOWSKA-DAWIDZIUK2 1 2

Department of Earth Sciences, University of Western Ontario, London, ON N6A 5B7, Canada Institute of Paleobiology, Polish Academy of Sciences, 51/55 Twarda, 00-818 Warsaw, Poland

The Late Wenlock, early Homerian graptolite extinction event (lundgreni extinction event) is now well recognized and studied in many parts of the world: Arctic Canada, Australia, Central Asia, (southern) China, Czech Republic, Germany, Poland, Portugal, Spain, UK. The overall dynamics of the extinction event and subsequent post-extinction recovery are, as a result, reasonably well known, although the exact cause of the extinction is still inadequately understood. Broadly speaking, a highly diverse lower Homerian (lundgreni Biozone) graptolite fauna consisting of "monograptids": Monograptus, Streptograptus, Monoclimacis, Testograptus, Pristiograptus, Diversograptus, Cyrtograptus, and retiolitids: Sokolovograptus, Retiolites, Paraplectograptus, Pseudoplectograptus, Eisenackograptus, Cometograptus, Gothograptus, became largely extinct during the event. Only the long-ranging and morphologically simple monograptid, Pristiograptus dubius, and the retiolitid, Gothograptus, survived and presumably became the progenitors of the morphologically very different upper Homerian and subsequent faunas. Graptolites are particularly well preserved in an uncompressed form in carbonates of the Cape Phillips Formation of the Canadian Arctic, and are readily released through acid dissolution. Our present study of uncompressed, as well as some compressed, graptolites from the lundgreni Biozone beds from several sections on Cornwallis Island and neighbouring islands, has yielded a biozone graptolite fauna with a species diversity greater than any previously recognised in the world, largely due to the remarkably fine preservation of the, sometimes, very delicate retiolitids. Our study of the Arctic biozonal material reveals the presence of at least 19 species of "monograptids" and 14 retiolitids most of which range through the entire biozone, and this, in spite of the absence of any of the several species of Gothograptus (one of which may be the ancestor of Gothograptus nassa\ recognized in this biozone in the East European Platform, and of two species of Cyrtograptus known elsewhere in the world. Of particular note, however, is the presence of a relatively diverse and apparently endemic fauna of six species of the recently-recognized Cometograptus lineage, comprising C. apoxys, C. apsis, C. bicladis, C. kirki, C. marsupium, and C. nevadensis. Only C. nevadensis is found outside the Arctic. In addition, two different species of Cometograptus from Poland, and probably another one from the Barrandian, and possibly eastern Australia, and all from the lundgreni Biozone, are also known. A further observation based on few data, suggests that some taxa, such as Retiolites and Sokolovograptus - the Arctic occurrences of which show the longest biostratigraphic range in the world - disappeared halfway through the biozonal interval, suggesting a limited stepwise extinction. Globally, then, the lundgreni extinction event witnessed the demise of 96% of the monograptids and 93% of the retiolitids! On Cornwallis Island, the highest lundgreni beds are characterized by the presence of graded beds, whereas those of the immediate post-extinction interval, the nassa-dubius Biozone, differ lithologically from the underlying or overlying intervals by lesser amounts of carbonates and greater amounts of silts and shales. Species diversity is low in the nassa-dubius Biozone, comprising only the abundant, opportunistic species Pristiograptus dubius and/or a closely related form, and Gothograptus nassa. Recovery and development of new morphotypes appear only in the overlying praedeubeli/deubeli Biozone, which in the Arctic, is marked by at least nine species of monograptids, mainly species of Colonograptus and Lobograptus, and more than seven species of retiolitids, primarily members of the Plectograptus and Gothograptus lineages. Globally, about twenty species are recognized in the interval.

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ARENIG CEPHALOPODS FROM SOUTHERN BOLIVIA JAROSLAV MAREK1, BERND WEBER2, FRANK SCHONIAN2, SVEN O. EGENHOFF2 and BERNDDIETRICH ERDTMANN2 1

Charles University, Institute of Geology and Palaeontology, Albertov 6, CZ-128 43 Praha 2, Czech Republic; mareki@natur.cuni.cz 2 Institute for Applied Geosciences II, Technical University Berlin, Ackerstrasse 71-76, D-13355 Berlin, Germany; webb0933@mailszrz.zrz.tu-berlin.de Fragments of cephalopod shells were found during sedimentological investigation of Ordovician successions in southern Bolivia, realised by a scientific team of the Technical University, Berlin. Cephalopods were collected from two localities of the lower Arenigian. The first locality (Chaupiuno, near El Puente at 21°19'S / 65°13'W) forms part of a Lower Ordovician succession of shallow water clastics, unconformably capped by Cretaceous sediments of the Camargo syncline (EGENHOFF & WEBER 1998). The second locality (Sella at 21°23'S / 64°40'W) is situated within a Tremadocian (?) to middle Arenigian succession of shallow water shelf sediments, disconformably overlain by Latest Ordovician tillites (SCHONIAN et al. 1999, MALETZ et al. 1995). The material adds new information to hitherto unsatisfactory known cephalopod fauna (CECIONI 1953, 1965) and palaeobiogeography of this part of Gondwana. Basal Arenigian, locality Chaupiuno, cca 55 km NW of Tarija, (EGENHOFF & WEBER 1998, ERDTMANN et al. 1995, MALETZ et al. 1995). Carbonatic nodules from the dark siltshales containing inside rather well preserved macrofauna, which from are at disposal cephalopods only. From associated fauna are present inarticulate brachiopods attached to ellesmerocerid cephalopod and tiny ostracod shells. Cephalopods: Bathmoceras sp. (sp. nov.?), Bactroceras aff. avus, Dideroceras sp. (large), endocerid sp. (small), ellesmerocerid sp. Lower Arenigian, locality Sella, cca 20 km N of Tarija, (MALETZ et al. 1995, SCHONIAN et al. 1999). Heavily weathered shallow water aleurites (originally carbonatic) with abundant fragments of shells forming lumachella composed of prevailing tiny bivalves (up to 5 mm; nuculid bivalves, heterodont bivalves, ? Babinka sp. and two other unidentified forms), associated with orthid brachiopods, asaphid trilobites, graptolites, rostroconchians (Ribeiria sp.) and echinoderms (possible crinoid holdfast). Cephalopods: Bathmoceras sp. (sp. nov.), Protocycloceras sp., ellesmerocerid sp.l, ellesmerocerid sp.2. All till now determined genera and species show palaeogeographic relations mainly to the Baltica and partly also to the L a u r e n t i a (see CRICK 1980, 1990; COCKS & FORTEY 1990).

REFERENCES CECIONI, G. 1953 Contribucion al conocimiento de los nautioloides-eopaleozoicos Argentinos. Parte I: Protocycloceratidae - Cyclostomiceratidae. Bol. Mus. Nac. Hist. Nat., 26(2): 57-110. CECIONI, G. 1965 Contribucion al conocimiento de los nautioloides-eopaleozoicos Argentinos. Parte II: Robsonoceratidae, Ellesmeroceratidae, Procerocameroceratidae, Baltoceratidae. Bol. Mus. Nac. Hist. Nat., 29(1): 1-24. COCKS, L. R. M. & FORTEY, R. A. 1990 Biogeography of Ordovician and Silurian faunas. Mem. Geol. Soc. London, 12 97-104.

CRICK, R. E. 1980 Integration of paleobiogeography: evidence from Arenigian nautiloid biogeography. J. Paleont., 54 (6): 1218-1236

CRICK, R. E. 1990 Cambro-Devonian biogeography of nautiloid cephaliopods. Mem. Geol. Soc. London, 12: 147-161 EGENHOFF, S. & WEBER, B. (1998): Ichnofauna trends in a shallowing - coarsening - upward succession : an example from the Arenigian of southern Bolivia. Abstr. Vol., 15th Internal Sedimentolog. Congr., Alicante (Spain), 1998: 311-312.

ERDTMANN B.-D., KLEY J. & MULLER J., JACOBSHAGEN V. 1995 Ordovician basin dynamics and new graptolite data from the Tarija region, Eastern Cordillera, South Bolivia. In Ordovician Odyssey, 7th ISOS, Las Vegas, 1995: 69-73. Fullerton.

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MALETZ, J., KLEY, J. & REINHARDT, M . 1995 New data on the palaeontology and biostratigraphy of the

Ordovician in southern Bolivia. Newsl. Strata 32(3): 163-173 SCHONIAN, F., EGENHOFF, S., MARCINEK, J. & ERDTMANN, B.-D. 1999 Glaciation at the Ordovician-Silurian

boundary in southern Bolivia. Acta Univ. Carol., Geol., 43: 1-2: 175-178

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SILURO-DEVONIAN (PRIDOLI-LOCHKOVIAN) CONODONTS FROM THE NOWSHERA AREA, PAKISTAN: IMPLICATIONS FOR THE MID-PALAEOZOIC STRATIGRAPHY OF THE PESHAWAR BASIN RUTH MAWSON, PETER D. MOLLOY, ANDREW J. SIMPSON and JOHN A. TALENT Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia The Kandar Formation (junior synonym, Panjpir Formation) spans most of Silurian time from LlandoveryWenlock to Pridoli, with its youngest horizons, documented by conodonts, falling within the Pridoli eosteinhornensis Zone. Portion of the conformably overlying (but perhaps locally unconformable) Nowshera Limestone of the Nowshera-Pir Sabak area falls within the eosteinhornensis Zone, but the bulk of this unit is inferred to extend from Early Devonian (Lochkovian) near Kandar through to at least perbonus Zone (early Emsian) or the succeeding inversus Zone in the highest beds exposed at Pir Sabak. The question of which if any of the intervening zones may be represented needs clarification. Regional considerations suggest that SilurianDevonian sequences around the eastern flank of the Peshawar Basin may display a conspicuous transgressive event within the Middle Devonian. This needs to be probed. It is suggested therefore that caution should be exercised before late Emsian and younger sequences around the Peshawar Basin are referred to the Nowshera Limestone - at least until additional stratigraphic-cum-sedimentary and chronologic data demonstrate continuity of sedimentation through the Middle Devonian for these sequences.

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FREDERICK McCOY: AUSTRALIA'S FIRST PALAEONTOLGIST DOUG McCANN School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn Rd, Clayton VIC 3068, Australia Congratulations are in order to the organisers of the Sir Frederick McCoy Silurian Symposium for naming the conference in McCoy's honour thus granting him some of the recognition he undoubtedly deserves. McCoy has received such a bad press over the years (partly his own fault) that he has become a somewhat neglected and denigrated figure in the history of Australian science. What is often overlooked is that despite his notorious public stouches McCoy in his prime was a talented palaeontologist of world standing and laid the foundations for an indigenous Australian-based palaeontology. Frederick McCoy (1823-1899) was born in Dublin and must have been a precocious youth - he published his first paper at 15 years of age and arranged the collections of the Museum of the Dublin Geological Society becoming a member of the Society at age 16. (A Catalogue of the Museum was published in 1841 - in effect his first publication on fossils). Around 1840 he was hired to determine the fossils collected by the staff of the Boundary Survey for the Geological Map of Ireland. Two notable publications resulted which firmly established McCoy as a capable palaeontologist: Synopsis of the Carboniferous Fossils of Ireland (1844) and Synopsis of the Silurian Fossils of Ireland (1846). In 1845 the Geological Survey of Ireland was instituted and McCoy was employed as the first staff member but only stayed briefly, without distinction, engaged in mapping rather than doing palaeontological determinations. Meanwhile, his earlier palaeontological work had attracted the attention of Adam Sedgwick and he was invited to Cambridge to arrange the fossil collection in the Woodwardian Museum which Sedgwick had assembled over many years. His collaboration with Sedgwick lasted for a period of some 8 years. Initially, he worked full-time on the project. He was competent and dedicated - working long days and well into the evening. Intending to take out a degree, McCoy also attended lectures in science and medicine but never graduated. He never really needed to because his reputation by now was such that in 1849 he gained a post as Professor of Geology, Mineralogy and Palaeontology at Queen's College, Belfast. However, he continued to work on the Sedgwick collection during vacations. The most important outcome of his collaboration with Sedgwick was a major monograph entitled, Synopsis of the British Palaeozoic Rocks and Fossils (1852), and also a series of about 28 palaeontological papers in the Annals and Magazine of Natural History (reprinted as a book, Contributions to British Palaeontology in 1854). Along with McCoy's earlier publications on the Irish Carboniferous and Silurian fossils these works constitute some of the foundation works of world Palaeozoic palaeontology. He was elected Fellow of the Geological Society of London in 1852. McCoy played a key role in the famous debate between Adam Sedgwick and Roderick Murchison on where to draw the boundary between the Cambrian and Silurian periods. McCoy provided Sedgwick with the fossil determinations he needed to justify his case. The argument was really only settled with the insertion of the Ordovician by Lapworth in 1879 as a kind of no-mans land between the Cambrian and Silurian periods (it took until 1960 for the Ordovician to gain full international recognition). While still in Great Britain McCoy worked on Australian fossils collected by the Rev. W.B. Clarke and sent to Sedgwick at Cambridge. In 1847, he published a significant paper based on this work titled "On the fossil botany and zoology of the rocks associated with the coal of Australia" in the Annals and Magazine of Natural History. This familiarity with Australian fossils was possibly one factor that enticed him into emigrating to Australia. McCoy applied for and secured the first professorship at the newly planned University of Melbourne. He arrived in the colony of Victoria in December 1854. Soon after his arrival in Victoria as Professor of Natural Science, McCoy set about clarifying issues connected with the local palaeontology and stratigraphy and was duly appointed Palaeontologist to the Geological Survey of Victoria in 1856. He moved quickly in taking over the colony's fledgling natural history museum and despite some spirited public opposition moved it from its city location to the grounds of the University of Melbourne. Overcoming many obstacles he was able to build the National Museum into a world class institution. He was appointed Director in 1858. 59

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In 1861 he published in the Victorian Exhibition catalogue the first comprehensive account on the zoology and palaeontology of Victoria. McCoy was able to show that based on palaeontological evidence the geological column in Australia conformed to that of Great Britain, Europe and North America. For the first time it could be stated unequivocally that the rock sequences in the Southern Hemisphere correlated precisely with those of the Northern Hemisphere. In other words, the geological column was a global phenomenon. This is a milestone in the history of geology that has largely gone unheralded. The breadth of McCoy's contributions to palaeontology and zoology, his scientific, philosophical and theological activities aimed at the public, and his administration of public institutions and societies, have not made him an easy subject of study. Because of the burden of his numerous institutional commitments and his extensive zoological work he never approached the prodigious output in his Australian palaeontological work that he achieved in Great Britain. His Prodromus of the Palaeontology of Victoria, published serially between 1874 to 1882, remained unfinished with the seventh issue or "decade". His Prodromus of the Zoology of Victoria was issued in twenty "decades" between 1878 and 1890. McCoy was a party to many disputes both scientific and public. McCoy's anti-evolutionary stance, which he shared with such luminaries as Sedgwick and Murchison, is probably another reason that his scientific achievements have not been widely acclaimed. Nonetheless, in his day he was an eminent authority and made lasting contributions not only locally but to international science generally. He accumulated many international honours during his lifetime. He was one of the pioneering figures of modern palaeontology and until the arrival on the local scene of Ralph Tate and Robert Etheridge, Jnr., he was without peer as palaeontologist in Australia.

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SEQUENCE BIOSTRATIGRAPHY AND EVOLUTIONARY PALAEOECOLOGY: FORAMINIFERA IN THE CAINOZOIC BRIAN McGOWRAN and QIANYU LI Department of Geology & Geophysics, The University of Adelaide, Adelaide SA 5005, Australia What is sequence biostratigraphy? There are three components: (i) The geochronology of sequence biostratigraphy uses standard bioevents to relate depositional sequences to global geochronology, including the refining of biostratigraphic events against marginal sequences, magnetochronology and the 87Sr/86Sr curve. It tests the timing of the sequence boundary and maximum flooding surface, (ii) Sequence biostratigraphy in basin analysis is the application of micropalaeontology to depositional sequences, clarifying the intra-sequence and inter-sequence architecture of a sedimentary prism or basin fill. It uses ratios such as planktonic/benthic and infaunal/epifaunal in seeking microfossil signatures of the major parts of the sedimentary sequence, (iii) The ecostratigraphy and paleobiology of sequence biostratigraphy is the taxic and biofacies profiling of secondand third-order sequences. This program relates fossil assemblages to sequences and draws such problems as recurrent biofacies and communities into a physical framework. Figure 2 describes the age/facies split and its modern healing.

Infaunal deposit eeders Fomminiferal (Protozoan) communities Figure 1. Reasons for studying the foraminifera. Benthics comprising a mix of epifaunal, infaunal and photosymbiotic strategists fossilize together with planktonics, themselves possessing a range of strategies (often overlapping). Their understanding was driven by classical biostratigraphy s.s. (i.e., correlation and age determination based on the reconstructed ordination ofspeciation and extinctions), and biofacies (fossil assemblages signalling environments and environmental change and cyclicity). These streams have been united recently in sequence stratigraphy and the search for cycles in the rock record. The flipside of these "geological" drives is the "palaeobiological" question of ancient communities and their long-timescale equivalents, chronofaunas. What is evolutionary palaeoecology? There are three merging kinds of evolutionary study of the fossil record: (i) identifying and calibrating evolutionary novelties and the consequent radiations; (ii) studying taxic diversity through geological time (taxic evolution); (iii) reconstructing the patterns of ecological organization and change through long periods of time, i.e., the anatomy of chronofaunas and chronofloras. This discipline is evolutionary palaeoecology, the logical and chronological bridge between ecology and evolutionary biology. Evolutionary palaeoecology meets the challenge of ancient biotas that are both too long-lived to be understood by extrapolation back from modern ecologies and too widespread across environmental spectra to be represented by the living world: the present provides us only with a narrow and blurred window into the past. It asks: How are communities maintained over 106-107 years? How do communities respond in the long run to environmental 61

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impact? Is the fossil record actually chunky—displaying stasis interrupted by major turning points—and hierarchical, or is that apparent chunkiness merely an artefact of preservation? The chronofauna perceived persistence through time by community types in terrestrial vertebrate communities. There was stability and coadaptation whilst evolution proceeded as an essentially self-contained entity held together by an elaborate set of positive and negative feedback loops. But are chronofaunas real, or an artefact, or a pretty metaphor? A prominent recent argument has been based in two worldviews named after prominent ecologists. In an "Eltonian" world, communities are exclusive associations of interdependent and coevolving species each with its own special role or niche. In a "Gleasonian" world in contrast, communities are haphazard samples of a regional species pool that just happen to be there and able to cope: it could have been other species and there is great ecological redundancy. Community ecology has shifted in the Gleasonian direction just as ecologists are learning to take the long view, discovering that neontology cannot by itself predict major patterns in the biosphere at 10 10 years' scales. 5

sequence blostratlgraphy subsumed in sequence stratigraphy & exogenic blogeohlstory

environmental forcing: putative global cycles & chemostratlgraphlc events

integrated geochronology in the IMBS A third-order blochronozones with chronological resolution myrs

third-order physical-ecological packets with duration ~ myrs

biozones In strata based in irreversible phylo-events

biofacies in strata based in reversible eco-events

ages & correlations of strata

depositlonal environments of strata

dfch<jtomy applied palaeontology: using the fossils found In strata

Figure 2. The age/facies split arose from the 18thC question: is that fossil informing us about the age or the depositional environment of this stratum? Hence classical biostratigraphic zones (left stream) and various ecostratigraphic events and units (right stream). Sequence biostratigraphy unites the two streams in the modem synthesis of sequence stratigraphy and exogenic biogeohistory. Foraminiferal communities and chronofaunas. Foraminifera contribute to three streams of enquiry into Cainozoic biogeohistory through their abundance, diversity and ease of recovery (Fig. 1). Biofacies are best understood in the conceptual trophic resource continuum (TRC) of low-to-high nutrients. Tethyan large foraminifera comprise a succession of chronofaunas at 10 -10 years' scale, and Indo-Pacific faunas display chronofaunal turnovers coeval with Tethys at end-Maastrichtian, late Bartonian, end-Priabonian, and endLanghian ages. At the southern edge of the province, immigrations mark provincial latitudinal expansion during global warmings, and the latter correlate with a strongly pulsing taxic turnover in New Zealand. 6

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A RESTUDY OF THE AKIDOGRAPTINE GRAPTOLITES FROM DOB'S LINN AND A PROPOSED REDEFINED ZONATION OF THE SILURIAN STRATOTYPE M.J. MELCHIN1 and S.H. WILLIAMS2 1

Department of Geology, St. Francis Xavier University, Antigonish, Nova Scottia, B2G 2W5, Canada, mmelchin@stfx.ca Department of Earth Sciences, Memorial University of Newfoundland, St. John's NF, A1B 3X5, Canada, williams@snarkv2.esd.mun.ca

The stratotype base of the Silurian System is defined in the Linn Branch stream section at Dob's Linn, Scotland, at 1.6 m above the base of the Birkhill Shale (COCKS 1985). This level coincides with the base of the acuminatus Zone. The biostratigraphic study on which this decision was largely based was done by Williams (1983), who defined the base of the P. acuminatus Zone by the first appearances of A. ascensus and P. acuminatus sensu lato. Unfortunately, the "sensu lato" designation of the latter taxon was omitted in some subsequent references to their occurrence in those samples (eg., COCKS 1985). This has caused difficulties in studies in other regions where A. ascensus is normally found to have its first occurrence below that of P. acuminatus sensu stricto. The question arose as to which of those two species should be regarded as indicative of the boundary, for purposes of international correlation. In order to resolve this problem we have restudied the material on which the WILLIAMS (1983) paper was based, as well as more recently collected samples from the same section taken at closer sample intervals (5 cm through the boundary interval), and extending into the overlying vesiculosus Zone. We found that although two different akidograptines can be found in the stratigraphic interval from 1.6-1.8 m above the base of the base of the Birkhill Shale, neither can be assigned to A. ascensus s.s. or P. acuminatus s.s. WILLIAMS (1983) suggested that the specimens he had referred to P. acuminatus s.l. might belong to P. acuminatus praematurus. Our restudy has shown that these specimens are indeed, referable to that taxon, but that there seems to be no known morphologic overlap between them and the specimens of P. acuminatus s.s., which occur higher in the section, beginning at 3.15 m. For this reason, we would regard P. praematurus as a distinct species. The other akidograptine occurring in the 1.6-1.8 m interval resembles A. ascensus in all respects except that it has a less protracted proximal end. In this case, however, there seems to be a morphologic continuum between these forms and the more typical specimens of A. ascensus in the overlying samples. For this reason, we regard the stratigraphically lowest specimens at and immediately above the stratotype level, as a new subspecies of A. ascensus. We can now affirm that at Dob's Linn, as at many other localities around the world, A. ascensus first occurs in strata substantially lower than P. acuminatus. Therefore, the strata that have previously been assigned to the acuminatus Zone at Dob's Linn should be divided into a lower ascensus Zone and a higher acuminatus Zone. The ascensus Zone marks the base the Silurian System and is recognized by the first appearances of A. ascensus n. subsp. and P. praematurus. A. ascensus ascensus makes its first appearance 20-30 cm above the boundary. Akidograptus ascensus n. subsp. and P. praematurus both resemble their probable normalograptid ancestors more closely than A. ascensus ascensus, P. acuminatus, or any other more derived akidograptines. Therefore, these taxa may represent evolutionary transients between a normalograptid and more typical akidograptines. If this is the case, then it indicates that the stratigraphic succession through this interval "captures" the evolutionary origins of the akidograptid species on which the zonation is based. REFERENCE COCKS, L.R.M. 1985. The Ordovician-Silurian boundary. Episodes, 8: 98-100. WILLIAMS, S.H. 1983. The Ordovician -Silurian boundary graptolite fauna of Dob's Linn, southern Scotland. Palaeontology, 26: 605-639.

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CORRELATION OF THE GRAPTOLITE AND CONODONT ZONATIONS AND CARBON ISOTOPE SIGNAL THROUGH THE LATE LLANDOVERY AND EARLY WENLOCK, CORNWALLIS ISLAND, ARCTIC CANADA M.J. MELCHIN1, R.J. HEATH2, D.M.S. JOWETT3, S.H. SENIOR4, C.R. BARNES3, AND J.D. MARSHALL5 1

Department of Geology, St. Francis Xavier University, Antigonish, Nova Scottia, B2G 2W5, Canada, mmelchin@stfx.ca Badley Ashton & Associates Ltd., Reservoir Geoscience Consultancy, Winceby House, Winceby, Horncastle, Lincolnshire, LN9 6PB, U.K. 3 School for Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, V8W 3P6, Canada 4 Department of Earth Sciences, University of Western Ontario, London, Ontario, N6A 5B7, Canada. 5 Department of Earth Sciences, University of Liverpool, PO Box 147, Brownlow Street, Liverpool, L69 3BX, U.K.

The type section of the Cape Phillips Formation on northeastern Cornwallis Island preserves a continuous record of sedimentation from the mid-Telychian (upper Llandovery), through most of the Wenlock and beyond. It yields well-preserved graptolites in both compressed and uncompressed form, conodonts, and other fossil groups including radiolaria, chitinozoa, and vertebrates. It is an organic-rich sequence of predominantly lime mudstones and calcareous shales of low thermal maturity and is thus well suited for stable isotopic analysis of the organic matter and whole-rock carbonate fractions. Detailed sampling through the upper Telychian, lower Sheinwoodian (lowermost Wenlock) interval has permitted resolution of a more complete graptolite biostratigraphy through this interval than was previously available. We can now recognize distinct sakmaricus and insectus zones in the upper Telychian and centrifugus and murchisoni zones in the lower Sheinwoodian. The upper portion of the murchisoni Zone overlaps with strata that had previously been assigned to the lowemost instrenuus-kolobus Zone. Thus the graptolite succession through this interval can now be more precisely correlated with successions in Europe. The major phases of faunal change within the graptolite succession occur within the uppermost sakmaricus Zone and the murchisoni Zone. Both of these levels have been previously recognized as graptolite extinction events (MELCHIN et al., 1998). Within the conodont succession, the strata through the Llanovery-Wenlock boundary interval can be assigned to the amorphognathoides Zone within the generalized conodont zonation, and the base of the overlying ranuliformis Zone appears to coincide closely with the top of the murchisoni Graptolite Zone. In addition, despite generally low conodont yields thought this interval, at least one other level within the high resolution "Standard Conodont Zonation" of JEPPSON (1998) can be tentatively recognized. The top of the lower bicornis Zone appears to correlate approximately with the base of the insectus Graptolite Zone. Other levels within the high resolution conodont zonation in the lowest Wenlock cannot be recognized due to relatively low diversity faunas and low overall yields. Nevertheless, it is clear that the Ireviken Event, a multistep phase of conodont extinction and faunal turnover (JEPPSON, 1998), begins within the uppermost sakmaricus Graptolite Zone and continues at least through the murchisoni Zone, into the overlying instrenuus-kolobus Zone. The signals of stratigraphic variation in whole-rock 613Ccart) and 813Corg both show a clear positive shift of approximately 3%o that begins near the sakmaricus-insectus zonal boundary, and then gradually declines beginning in the murchisoni Zone, into the instrenuus-kolobus Zone. Thus, the timing of the positive and negative shifts generally coincides with the peak phases of extinction in both the graptolites and conodonts. This C-isotope excursion has been widely recognized in other regions, especially in limestones in Baltica. If the excursions are precisely correlative worldwide, we can now affirm the timing of this event in relation to the graptolite zonation as noted above. As with the Late Ordovician event, there is good evidence that the positive C-isotope excursion coincides, at least in its early stages, with a sea level fall that may have been glacio-eustatic in origin. It is noteworthy that although the overall timing and magnitude of the 513Ccarb and 5I3Corg shifts are similar, their patterns differ somewhat in detail. In particular, the S13Corg rises abruptly to peak values near the sakmaricusinsectus zonal boundary and remains relatively constant until its decline beginning in the murchisoni Zone. By contrast the 513Ccarb rises gradually to a peak in the lower murchisoni Zone, followed by gradual decline. These differences may be caused by one or more of the following factors: different diagenetic processes influencing the carbonate and organic fractions; changing local rates of detrital input of recycled carbonate due to changing sea levels; changes in the nature of the organisms contributing to the organic matter; and/or changing atmospheric 64

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C0 resulting in shifts in the relative proportions of the 5 C and 8 C g values. Changes in rates and styles of erosion, atmospheric C0 composition, and local faunal/floral communities can all be expected to accompany an episode of glaciation so the precise C-isotope signal changes may not be resolvable to a single causal factor.

carb

REFERENCES JEPPSON, L. 1998. Silurian oceanic events: summary of general characteristics. In: Silurian Cycles: Linkages of

Dynamic Stratigraphy with Atmospheric, Oceanic and Tectonic Changes. New York State Museum Bulletin 491,239-257.

MELCHIN, M.J., KOREN', T.N. AND STORCH, P. 1998. Global diversity and survivorship patterns of Silurian

Graptoloids. In: Silurian Cycles: Linkages of Dynamic Stratigraphy with Atmospheric, Oceanic and Tectonic Changes. New York State Museum Bulletin 491, 165-182.

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COLOUR AND TEXTURAL ALTERATION OF PALAEOZOIC AND TRIASSIC CONODONTS FROM PENINSULAR MALAYSIA: IMPLICATIONS FOR TECTONIC EVOLUTION AND HYDROCARBON GENERATION L METCALFE Asia Centre, University of New England, Armidale, NSW 2351, Australia Colour Alteration Indices (CAIs) of conodonts in Peninsular Malaysia range in value from 1.5 to 8 (Figure 1). The lowest values are found in Triassic limestones in northwest Peninsular Malaysia and the highest values occur in Palaeozoic strata within or close to zones of deformation or to intrusives. Palaeozoic conodonts from the Sibumasu Block (Western Belt of Peninsular Malaysia) show a background value of CAI 5, all conodonts of Ordovician to Middle Permian age showing CAIs of at least 5 and locally up to 8. Palaeozoic conodonts of Sibumasu exhibit textural alteration interpreted as due to regional metamorphism, whereas Triassic conodonts exhibit little textural alteration. The disparity between CAIs and textural alteration of Palaeozoic vs. Triassic conodonts of Sibumasu suggests regional metamorphism of these rocks around the Palaeozoic/Mesozoic boundary which is consistent with the previously suggested timing for initial collision between the Sibumasu and Indochina blocks. Upper Palaeozoic conodonts from the Indochina Block (Central and Eastern Belts), however, are more variable. Late Lower Carboniferous (Namurian) conodonts from the Panching Limestone in the Eastern Belt exhibit a CAI of 3 and appear to have escaped the effects of the regional metamorphism that affected the coeval rocks on the Sibumasu Block. Permian conodonts from limestones along the western margin of the Central Belt have an anomalously high CAI of 5, probably caused by the heating effect of the Main Range Granitoids.

Fig. 1. Map of Peninsular Malaysia showing conodont localities and CAI values with age. Conodont localities: 1. Setul Limestone, Langkawi Island. 2. Setul Limestone, Kaki Bukit. 3. Kanthan Limestone, Gunong Kanthan, Perak. 4. Kanthan Limestone, Batu Gajah, Perak. 5. Sungai Bilut Limestone, and Krau Satu Limestone, Raub, Pahang. 6. Panching Limestone, Panching, Pahang. 7. Gua Panjang, Pahang. 8. Gua Sei, Kampong Gua, Pahang. 9. Kodiang Limestone, Gunong Keriang, Kedah. 10. Kodiang Limestone, Bukit Kecil 1, Kedah. 11. Kodiang Limestone, Bukit Kepelu, Kedah. 12. Semanggol Formation, Kedah. 13. Sungei Jeleteh Limestone, Pahang. 14. Jerus Limestone, Pahang. 15. Semantan Formation, Pahang. O = Ordovician. S = Silurian. D = Devonian. C = Carboniferous. P = Permian. T = Triassic. L = Lower. U = Upper.

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Triassic conodont CAIs for Peninsular Malaysia show an overall range of 1.5 to 5. The lower values of 1.5-2.5 are found in conodonts from the Kodiang and Chuping limestones of northwest Peninsular Malaysia and indicate that these sediments fall within the mature liquid hydrocarbon window. This indicates that these, and similar early Mesozoic sediments buried beneath offshore Cenozoic sediments, may have acted as source rocks for hydrocarbons now trapped in Mesozoic and Cenozoic sedimentary basins of the region. Conodonts from the Lower-Middle Triassic of Gunong Keriang, south of the main Kodiang limestone, appears to be anomalous with CAIs of 3-4. These higher values are unlikely to be caused by extra overburden but could be due to the presence of a subsurface intrusion. Gravity data from the area, however, suggests that this is not the case and that migration of hydrothermal fluids may be the cause. High Triassic values of CAI 5 are recorded from LowerMiddle Triassic limestones along the western margin of the Central Belt and are probably the result of heating by the Main Range Granitoids of latest Triassic-Early Jurassic age. Values pf CAI 5 are also recorded from Middle Triassic pelagic limestones associated with cherts of the Semanggol Formation in Kedah. This CAI value implies an overburden of 7,500-10,000 metres if the CAI is due solely to burial but the estimated maximum overburden is only 3,500 metres indicating that the CAI is anomalously high.

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THE ORDOVICIAN AND SILURIAN ROCKS OF MONGOLIA Ch. MINJIN Mongolian Technical University, Ulaanbattar-46, P.O. Box 46/520, Mongolia Ordovician rocks: Ordovician sediments were recognised from palaeontological material in the Mongolian Altai, Govi Altai, South Mongolia and Bayanhongor regions. Through inferences from stratigraphy, probable Ordovician sediments can be identified in the Mongolian Altai, Hangai and Hentii regions. Upper Ordovician deposits are the most widely distributed of all Ordovician rocks found in the territory of Mongolia. In the Tsagaan Shiveet zone of the Mongolian Altai, 500-700m thick Middle-Upper Ordovician volcanogenic terrigenous and carbonate sediments, containing brachiopods have been recognised. A 2000m thick sandstone and shale unit, situated in the Tonhil subprovince of the southern part of the Mongol Altai Hovdyn belt, was identified as Lower and Middle Ordovician in age from graptolites, and a type section was selected. In the Hajingiin Nuruu, Botgony Havtsal, Hoit Tsenher Gol and Achit Nuuryn basin, a 100-400 m thick limestone, aleurolite and sandstone rock unit of marine shelf origin with corals and brachiopods is known. In southern Mongolia's Gichgen Nuruu, a Lower-Middle Ordovician terrigenous and volcanoclasitc rock unit with a sequence of brachiopod faunas has been discovered. Middle-Upper Ordovician faunas are known from a 10002000m thick carbonate, terrigenous and tuffaceous sedimentary unit in the Shinejinst and Bayangovi region. A terrigenous rock mass with limestone layers and coral faunas is 2000-3000m thick in the eastern part of South Mongolia, Undershil and Altan-Shiree subprovinces. A 1500m thick terrigenous rock unit around Tavan Har Uul south from the Zuun Bayan, a limestone and aleurolite rock unit with coral remains, and a 300m thick unit around Shovdol-Ovoo, south from the Baruun Urt town contain Middle Ordovician faunas. A 500m thick limestone, gravelstone and conglomerate with the Upper Ordovician corals is known from the thin graben of the Bayanhongor belt. The thick terrigenous rock units that can not be accurately dated from palaeontological material are known in the Mongolian Altai (the Uulynaltain series), Hangai (the Zag series) and Hentii (the Haraa series). Silurian rocks: These sediments are found in the Mongolian Altai, in the Nuur Basin of South and Eastern Mongolia. All Silurian stages have been recognised from graptolite, coral, and brachiopod data. In the Mongolian Altai, mainly in the Hovd zone's Hajingiin Nuruu and Botgony Havtsal, Ordovician units are conformably overlain by Silurian strata. A 2000-3000m thick rock unit consisting of limestone, aleurolite, shale, basic, medium and acidic volcanics and associated tuffs is known to contain graptolite and brachiopod faunas. In the basin of Ih Nuur around the Togtohyn Shil and the Har-Us Lake, there is a red coloured sandstone, aleurolite and conglomerate with coral and brachiopod remains from marine intervals. In the western part of the Mongolian Altai the Silurian section begins with a 500-1000m thick unit of grey and red conglomerates and quartz sandstone. Lower Silurian limestone and mudstone with corals and brachiopods are found here. In Southern Mongolia Silurian sediments occur as belts with east-west strike in the Shinejinst, Ulaan Han Uul, Arts Bogd, Mushgai Hudag, Haraat Shand and Baruun Urt regions. In the Shinejinst region Upper-Lower Silurian limestone, aleurolite and sandstone rock units with a marine shelf fauna and a thickness of 1000m was studied and nominated as the type section. Around the Mushgai Hudag region this rock mass has turbidic intervals. In the Haraat-Shand and Baruun Urt contains a higher proportion of carbonates. In the Ulaan-Han Uul and Havtgai Uul area Silurian sedimentation was related to the inception of orogenic molasse. In the southern border of Mongolia, around Tsagaan Nuur, a 500m thick limestone with a Lower Silurian fauna has been discovered. In the Central Mongolia, around Bayanhongor, a 300m thick Lower Silurian graptolitebearing black shale and marine sandstone unit is known. In the Herlen River's basin in the Bud Uul, Baytsyn Ovoo region, a 2000m thick sandstone and shale unit with limestone intercalations yielding brachiopod faunas is known. This extension of this unit has been identified in the Shuus River region south from the Onon River. In the Govi Tenger Uul and Halhyn Gol region there are sedimentary intervals with a non specific Silurian age.

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INTEGRATED SILURIAN CHITINOZOAN AND GRAPTOLITE BIOSTRATIGRAPHY OF THE BANWY RIVER SECTION, WALES, UK GARY L. MULLINS1 2 and DAVID K. LOYDELL1 1

School of Earth, Environmental and Physical Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth POl 3QL, United Kingdom 2 (Current Address) Department of Geology, University of Leicester, University Road, Leicester LEI 7RH, United Kingdom The Banwy River section (Powys, Wales) exposes a succession of strata including the upper Llandovery and lower Wen lock. Graptolitic horizons are found throughout the sequence (in thin mudstone-shale bands in the upper Llandovery-lowermost Wenlock and in thick hemipelagite units higher in the Wenlock). Graptolites from these horizons allow recognition of the crispus, sartorius, spiralis, lapworthi and insectus biozones (Llandovery) and centrifugus, murchisoni, firmus and riccartonensis biozones (Wenlock; see LOYDELL & CAVE 1996). Samples from these graptolitic horizons have been processed for the recovery of chitinozoans, thus allowing a direct correlation between the two biostratigraphical schemes. A succession of thirty-eight chitinozoan taxa has been recorded in the Banwy River section. These taxa include Eisenackitina dolioliformis, Angochitina longicollis and Margachitina margaritana, the index taxa of three of the 'global' chitinozoan biozones proposed by VERNIERS et al (1995). The first E. dolioliformis are recorded in the lowermost sample from the Banwy River section and it is therefore probable that the base of this biozone has not been recognised. The first occurrence of specimens of A. longicollis and M. margaritana have, however, been directly correlated with the graptolite biostratigraphical scheme. In addition to the 'global' chitinozoan biozones, three local biozones have been defined in the Banwy River section (Margachitina banwyensis, Cingulochitina bouniensis and Salopochitina bella). The bases of these biozones have been directly correlated with the graptolite biostratigraphical scheme and it is possible that they may enhance resolution of the chitinozoan biostratigraphical scheme outside the Banwy River area. The chitinozoan data obtained from the Banwy River section have been compared with published data from several sections where graptolite biostratigraphical control exists (Ohesaare borehole, Estonia-NESTOR 1994; LOYDELL et al. 1998; Prague Basin, Czech Republic-DUFKA 1992; DUFKA et al 1995; Builth Wells area, Wales-ZALASiEWicz & WILLIAMS 1999; VERNIERS 1999; Gotland and mainland Sweden-GRAHN 1995, 1998). This comparison of data has shown that the base of the E. dolioliformis chitinozoan biozone cannot (at present) be correlated with the graptolite biostratigraphical scheme with any certainty. It has also highlighted problems with the correlation of the A. longicollis biozone with the graptolite biostratigraphical scheme and identified areas where further research is required. REFERENCES DUFKA, P. 1992. Lower Silurian chitinozoans of the Prague Basin (Barrandian, Czechoslovakia) -

preliminary

results. Revue de Micropaleontologie, 35: 1 1 7 - 1 2 6 . P., KRIZ, J. & STORCH, P. 1995. Silurian graptolites and chitinozoans from the Uranium Industry boreholes drilled in 1968-1971 (Prague Basin, Bohemia). Vestnik Ceskeho geologickeho ustavu, 70: 5-14.

DUFKA,

GRAHN, Y. 1995. Lower Silurian Chitinozoa and biostratigraphy of subsurface Gotland. GFF, 117: 57-65. GRAHN, Y. 1998. Lower Silurian (Llandovery-Middle Wenlock) Chitinozoa and biostratigraphy of the mainland

of Sweden. GFF, 120: 273-283. LOYDELL, D. K. & CAVE, R. 1996. The Llandovery-Wenlock boundary and related stratigraphy in eastern mid

Wales with special reference to the Banwy River section. Newsletters on Stratigraphy, 3 4 : 3 9 - 6 4 . LOYDELL, D. K., KALJO, D . & MANNIK, P. 1998. Integrated biostratigraphy of the lower Silurian of the Ohesaare

core, Saaremaa, Estonia. Geological Magazine, 135: 7 6 9 - 7 8 3 . NESTOR, V. 1994. Early Silurian chitinozoans of Estonia and North Latvia. Academia, 4: 1-163

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VERNIERS, J. 1999. Calibration of Chitinozoa versus graptolite biozonation in the Wenlock of Builth Wells

district (Wales, U.K.), compared with other areas in Avalonia and Baltica. Bolletino della Societa Paleontologica Italiana, 38: 359-380. VERNIERS, J., NESTOR, V., PARIS, F. DUFKA, P., SUTHERLAND, S. & VAN GROOTEL, G . 1995. A

global

Chitinozoa biozonation for the Silurian. Geological Magazine, 132: 6 5 1 - 6 6 6 . ZALASIEWICZ, J. & WILLIAMS, M. 1999. Graptolite biozonation of the Wenlock Series (Silurian) of the Builth

Wells district, central Wales. Geological Magazine, 136: 263-283.

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THE MISTAKEN POINT ASSEMBLAGE (EDIACARIAN) OF EASTERN NEWFOUNDLAND: A NEW LOOK AT SOME OLD FOSSILS GUY M. NARBONNE, JAMES G. GEHLING and R.W. DALRYMPLE Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, ON, Canada K7L 3N6 The Mistaken Point assemblage (565±3 Ma) is the oldest diverse assemblage of complex macroscopic organisms in the world. Fossils are spectacularly exposed on large, tennis court-sized bedding surfaces, with scores to thousands of specimens preserved on each of these surfaces. Ediacaran fossils range though four successive formations that collectively span several kilometers of strata. A few of the taxa are cosmopolitan (eg. Charnia, Charniodiscus, Aspidella) and a few are known from equivalent strata in the Avalon Zone of England (eg. Bradgatia), but most apparently are restricted to the Mistaken Point assemblage. Our research program has focused on elucidating the nature of the fossils, their ecology, and their evolution through the section. The unusual preservation of the fossils both permits and requires techniques not commonly used in studies of other Ediacaran assemblages. Fossils are preserved almost exclusively as impressions on the upper surfaces of beds, and their morphology is most easily studied on latex molds of the fossils. Retrodeformation of fossil images (to remove the effects of 40% tectonic shortening perpendicular to cleavage) is necessary to determine the true shape and angular relationships of the organisms. Preservation of the fossils as census populations under beds of volcanic ash provides a unique opportunity to apply ecological models derived from study of modern living communities, and makes Mistaken Point a superb natural laboratory to assess late Neoproterozoic community structure. Most of the common taxa of the Mistaken Point assemblage occur through hundreds or even thousands of meters of strata. Evidence of evolutionary development may be present in the "spindles", which appear to comprise two biostratigraphically-restricted species. Our study of the presumed pseudofossil Aspidella terranovica Billings, 1872 implies that it is organic and represents the first Ediacaran-type fossil named anywhere in the world. The Mistaken Point assemblage has commonly been regarded as having lived in a deep-water, oceanic setting. Our discovery of abundant hummocky cross-stratification (HCS) and bipolar fossil orientations implies a shallower water setting, above storm wave-base and perhaps within the photic zone, an environment similar to that interpreted for most classic Ediacaran assemblages (eg. South Australia, White Sea, Namibia). Trace fossils and bilaterian body fossils are abundant in these younger Ediacaran assemblages but are conspicuously absent from the Mistaken Point assemblage. This implies that the unusual composition of the Mistaken Point assemblage represents an early stage in the evolution of the Ediacara biota that may predate the first appearance of large mobile metazoans.

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NEW SEPTIMEMBRATE CONODONT TAXA OF THE FAMILY OEPIKODONTIDAE FROM THE EARLY ORDOVICIAN OF AUSTRALIA AND NEVADA ROBERT S. NICOLL1 and RAYMOND L. ETHINGTON2 department of Geology, Australian National University, Canberra, ACT, 0200, Australia department of Geology, University of Missouri-Columbia, Columbia, Missouri, USA Two species of the Early Ordovician (Arenig) conodont Family Oepikodontidae are described using material obtained from Amadeus and Canning Basins of Australia and Great Basin of Nevada. The species are Oepikodus sp. nov. A and Gen. nov. A sp. nov. A. A septimembrate apparatus structure is recognized for each of these species. Species assigned to the genera Oepikodus and Gen. nov. A can be distinguished from species of the genus Prioniodus by the presence of a quadform alate Sa element rather than a triform alate Sa element. The evolutionary relationship of these species is briefly discussed, as is their biostratigraphy. The terms biform, triform and quadform are introduced to define the process morphology of the symmetrical alate Sa element of the conodont apparatus.

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PALAEOINFORMATICS: TOOLS FOR THE MANAGEMENT PALAEONTOLOGICAL INFORMATION.

AND DISSEMINATION

DAVID A. NIPPERESS Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW. 2109, Australia Recent advances in the development of biodiversity information technology are readily applicable to palaeontological information. This paper is essentially a discussion of the various software and hardware technologies available and how they can be applied to both teaching and research in the palaeosciences. All research utilising taxonomic data, whether biostratigraphy, biogeography, systematics or ecology, ultimately relies on the information provided by specimens. Many research agendas require data from hundreds to thousands of specimens. Clearly, some technological solutions to the curatorial problems resulting from large specimen collections, would benefit such research. Specimen management databases are particularly useful informatics tools for research purposes. In these typically relational databases, the essential elements of specimen information (what is it, where was it found, who found it) can be recorded in an efficient and retrievable format. While the author is not aware of any software packages specifically catering to palaeontological information, more general packages, such as Biota™ have proven suitable. Specimen curation also benefits from the use of barcodes. As in department stores, barcode technology greatly expedites the management of a large inventory of objects. It has been estimated that the use of barcodes saves one researcher at least a quarter of a million keystrokes a year (THOMPSON 1994). Barcodes are used widely in museums and herbaria, and in some biodiversity research laboratories (OLIVER et. al 2000). Palaeontological research laboratories could similarly benefit. Computer-aided identification tools are applicable to both teaching and research in the palaeosciences. Typically, these tools are in the form of a multi-access key which differs from the traditional dichotomous key in that the user decides the order in which character states are entered. This feature, combined with the liberal use of digital images, makes such software more 'user-friendly' and flexible than traditional identification techniques. Commercial packages available include DELTA™, LucID™ and Linnaeus II™. The phenomenon of ever increasing hard drive capacities and RAM allocations, coupled with falling prices, make the use of high resolution digital images within the capabilities of most researchers. New technologies, such as high resolution digital cameras, and montaging software (eg. AutoMontage™) allow for fully focused images of specimens previously too small to capture without using SEM techniques. Digital images, posing as 'virtual specimens', have the potential to revolutionise taxonomic practises through their ready transfer via the internet. REFERENCES I, PIK A, BRITTON D , DANGERFIELD JM, COLWELL RK & BEATTIE AJ. 2000. Virtual biodiversity assessment systems. Bioscience 50: 441-450.

OLIVER

THOMPSON FC. 1994. Bar codes for specimen data management. Insect Collection News 9: 2-4.

Papers

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LATE SILURIAN AND EARLY DEVONIAN BIOSTRATIGRAPHY IN THE HILL END TROUGH AND THE LIMEKILNS AREA, NEW SOUTH WALES G.H. PACKHAM ,1.G. PERCIVAL , R.B. RICKARDS , and A.J. WRIGHT 1

1 2 3 4

School of Geosciences, University of Sydney, NSW 2006, Australia Geological Survey of New South Wales, P.O. Box 76, Lidcombe, NSW 2141, Australia Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, U.K. School of Geosciences, University of Wollongong, NSW 2522, Australia

The stratigraphic sequence for the eastern and central part of the Hill End Trough is: Tanwarra Shale (lowest), Bells Creek Volcanics, Chesleigh Formation, Cookman Formation, Turondale Formation, Waterbeach Formation, Merrions Formation and Cunningham Formation (highest). Correlation between these strata and those of the adjacent western flank of the Capertee High in the Limekilns district previously relied mainly on lithostratigraphic similarity and isotopic age dating, with few palaeontological constraints. The first recorded graptolites from the Chesleigh Formation of the Limekilns district are Monograptus prognatus, 1M. transgrediens, Pristiograptus sp. cf. P. shearsbyi and Linograptus posthumus, which unequivocally indicate a Pfldoli (Late Silurian) age for the formation. The location of the Silurian-Devonian boundary appears best placed at approximately the boundary between the Chesleigh Formation and the overlying Cookman Formation, despite the presence of the early Lochkovian graptolite Monograptus uniformis uniformis much higher stratigraphically, in the Limekilns Formation near Limekilns. In the Hill End Trough succession, the top of the Turondale Formation has yielded conodonts including the alpha morph of Amydrotaxis Johnsoni, which indicates an interval spanning the delta and basal pesavis zones of late Lochkovian (Early Devonian) age. Conodonts from the upper part of the Cunningham Formation, at a locality west of Mudgee, include Polygnathus nothoperbonus / P. inversus, indicating the perbonus zone of middle Emsian age. The base of the Cunningham Formation is diachronous, being late Lochkovian {delta Zone) - the same age as the Turondale Formation - on the west flank of the Trough as previously reported, and late Pragian in the east. The youngest faunas found in the unit are late Emsian. On the basis of these considerations, the best estimates of the ages of the intervening formations are latest Lochkovian to early Pragian for the Waterbeach, and mid-Pragian for the Merrions Formation. These ages are in general agreement with the U-Pb zircon dates determined by JAGODZINSKI & BLACK (1999) using the time scale of TUCKER et al. (1998). This estimate of the age of the top of the Merrions Formation correlates well with the end of the major phase of Early Devonian volcanic activity on the adjacent Capertee High. REFERENCES JAGODZINSKI, E.A. & BLACK, L.P. 1999. U-Pb dating of silicic lavas, sills and syneruptive resedimented

volcaniclastic deposits of the Lower Devonian Crudine Group, Hill End Trough, New South Wales. Australian Journal of Earth Sciences 46, 749-764.

TUCKER, R.D., BRADLEY, D.C., VER STRAETEN, C.A., HARRIS, A.G., EBERT, J.R. & MCCUTCHEON, S.R. 1998.

New U-Pb zircon ages and the duration and division of Devonian time. Earth and Planetary Science Letters 158, 175-186.

[ IGP publishes with permission of the Director General, New South Wales Department of Mineral Resources]. 2

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THE ULTIMATE EFFECTS OF THE LATE ORDOVICIAN GLACIATION ON NORTHERN GONDWANA CHITINOZOANS F. PARIS and A. BOURAHROUH G6osciences-Rennes, UPR 4661 du CNRS, University de Rennes I, campus de Beaulieu, 35042 Rennescedex, France Chitinozoan assemblages from the uppermost Ordovician-lowermost Silurian of various northern Gondwana localities are used to date the ultimate effects of the Late Ordovician glaciation and to evaluate the impact of this major climatic event on the diversity of the palynoplankton. The post-crisis recovery of the palynomorphs is also documented. The local age determinations are improved by using a calibration based on the global eustatic sea-level variations and on the excursions of stable isotopes in other sections. These short-lived events are regarded here as "timelines" at the scale of the Upper Ordovician. The glacio-marine diamictites, widely distributed over the northern Gondwana domain, are interpreted as resulting from the melting of most of the ice cap covering a large part of Africa and of the Arabian Peninsula, and from the subsequent transgressive event. These diamictites yield poorly preserved and moderately diverse chitinozoans of late Hirnantian age. Some reworking of older Ordovician taxa are observed. The shallow marine sediments overlying these glacially derived deposits yield better preserved, more abundant and more diverse chitinozoans assemblages of latest Hirnantian age. The composition of the palynoplankton indicates a fairly good and rapid faunal and phytoplankton recovery after the early Hirnantian climatic stress. The extinction of the Ordovician chitinozoan species and the appearance of Silurian type taxa occurred only in the uppermost Hirnantian, i.e. with a slight delay after the glacial event. The lowermost Silurian deposits seem restricted to areas, usually located in regions where glacial floors have been documented (eg., Mauritania, southern Sahara, Saudi Arabia) or in areas corresponding to deeper parts of the Rheic basin (eg., Bohemia, Sardinia, Southern Spain). In the first case the basal Rhuddanian transgression preceded the final isostatic readjustment released by the melting of a thick ice cover. In the second case, the fall of the sea level was not sufficient to induce any significant sedimentary brake close to the Ordovician-Silurian boundary. The anoxia that characterised most of the Llandovery to Wenlock black shale formations in northern Gondwana regions is not directly related to the Late Ordovician Glacial event. Indeed, the topmost Ordovician and earliest Silurian deposits yield a few benthic faunas and numerous palynomorphs not affected by the severe anoxic conditions that prevailed later. On the other hand, the peculiar composition of the Llandovery-Wenlock palynoplankton in most northern Gondwana localities seems to result from the anoxia. Only green micro-algae (leiospheres and tasmanites) proliferated in the well-lit upper layers of the southern margins of the Rheic ocean. This anoxia seems to be independent of the Late Ordovician glaciation and was likely provoked by other palaeogeographic, and climatic/environment interacting factors that, later, generated and maintained anoxic conditions over this large area. The high level of production of these green algae in a nutrient rich ocean was at least one of the factors that maintained the anoxic conditions for a long period and generated extensive oil source rocks in northern Gondwana regions. However, this massive burial of organic carbon during the Silurian in northern Gondwana regions was not accompanied by a strong positive 6 l 3 C excursion.

Papers

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BOLINDIAN (LATE ORDOVICIAN) BIOSTRATIGRAPHY OF CENTRAL NEW SOUTH WALES IAN G. PERCIVAL1, LAWRENCE SHERWIN2 and JOHN PICKETT1 1

Specialist Services Section, Geological Survey of New South Wales, PO Box 76, Lidcombe, NSW 2141, Australia Geological Survey of New South Wales, PO Box 53, Orange, NSW 2800, Australia

All reported occurrences of fossiliferous strata of Bolindian age in central NSW are reassessed. Areas of outcrop examined include the Molong Volcanic Belt from south of Orange and north to near Wellington, and part of the Junee-Narromine Volcanic Belt from near Grenfell north to Forbes. In the Belubula River Valley near Cliefden Caves, graptolites (including Climacograptus uncinatus) date the top of the Malongulli Formation as Bolindian 1. The overlying Angullong Formation contains sparse graptolites, corals, sponges and brachiopods. A graptolite fauna previously correlated with the Dicellograptus anceps Zone of the British succession is recorded from near the top of this formation; this assemblage and others from this level are indicative of a Bolindian 2-3 age. Graptolites of Bolindian age from the contemporaneous upper member of the Cheesemans Creek Formation include Amplexograptus latus. An age range of Bolindian 1-3 is suggested by this fauna. Other stratigraphic units, including the Sourges Shale and Kabadah Formation in the Cumnock region, which were previously interpreted to span the Ordovician-Silurian boundary, are shown to include depositional breaks covering the late Bolindian to earliest Llandovery interval. The deep-water shelly fauna of the Jingerangle Formation, exposed north of Quandialla (southwest of Grenfell), includes nautiloids, brachiopods, and sponges. Graptolites date this unit as Bolindian 2. The lower part of the lithologically similar Cotton Formation, extending north towards Forbes, contains Bolindian graptolites which are described here for the first time. Evidence for continuity of these beds with the upper (early and late Llandovery) sections of the Cotton Formation is critically examined. As elsewhere in central NSW, no indubitable record exists of assemblages diagnostic of (restricted to) the terminal Bolindian or earliest Llandovery graptolite zones. Recent revision of the Ordovician-Silurian boundary, based on radiometric methods, places its age at either 441 Ma or 443 Ma. This age coincides with a short period of intense intrusive igneous activity across the central part of the Lachlan Fold Belt in NSW. Thermal doming associated with this event appears to have been responsible for a corresponding stratigraphic break in shallow water deposition throughout the region, extending in almost all instances through the equivalent of two graptolite zones on either side of the Ordovician-Silurian boundary. In deep-water successions, this depositional disruption is indicated by development of submarine canyon erosion. The otherwise cosmopolitan Hirnantia Fauna, of latest Ordovician age, has not been recognised in NSW successions. Its absence locally also may imply the presence of a depositional hiatus at this time. ['Published with permission of the Director General, NSW Department of Mineral Resources. This is a contribution to IGCP 410 "The Great Ordovician Biodiversification Event".]

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CONODONTS ACROSS THE PERMO-TRIASSIC BOUNDARY IN THE SOUTHERN ALPS MARIA CRISTINA PERRI and ENZO FARABEGOLI Dipartimento di Scienze delta Terra e Geologico-Ambientali, perri@geomin.unibo.it. fara@geomin.unibo.it

University

Bologna,

Italy

In the Southern Alps a medium-high sedimentation rate of the sequence across the Permo-Triassic (P-T) boundary allowed recognition of evolutionary trends in morphology in the conodont fauna consisting mainly of hindeodellids and isarcicellids. The studied conodonts come from the uppermost beds of the Bellerophon Formation and from the lower part of the Werfen Formation, the Tesero and Mazzin Members. An erosional regionally paraconformable surface separates the two formations; small cavities filled with calcite cements (microkarst) locally characterize the uppermost beds of the Bellerophon Formation. Subaerial erosion occurred during a low-stand period, associated with a cold interval. The lowermost portion of the Werfen Formation, corresponds to the few meters thick P-T transgressive-regressive (H.S.) sedimentary wedge, whereas the last appearance of Permian taxa seems to be connected with a maximum flooding surface (FARABEGOLI et al. 1986; FARABEGOLI & PERRI 1998). The Bellerophon Formation produced conodonts only in the western Carnic Alps where a few hindeodellid elements were collected immediately below and above the lithostratigraphic boundary of the two formations (PERRI & ANDRAGHETTI 1987). The most abundant conodont fauna was found in the western Dolomites where the first conodonts make their entry a few centimeters above the base of the Werfen Formation (PERRI 1991; FARABEGOLI & PERRI 1998; NICORA& PERRI 1999). Some gradual morphological changes can be discriminated in the conodont associations, such as reduction in conodont length compared with height, increase in width and asymmetry of the basal cavity, becoming a cup with lateral lobes bearing nodes. The laterally compressed wide denticles tend to be reduced to higher, narrow and rounded denticles. The cusp doubles its height. The posterior end can be either adenticulate abruptly ending, or denticulate with little denticles reaching the posterior tip. The peculiarity of the thickness and swelling of the basal cavity and of the attachment area of the denticles giving the conodont a swollen appearance has been considered to be taxonomically significant. Forms showing this last feature, characteristic of the genus Isarcicella, became dominant in stratigraphically highest levels. On the basis of the above-mentioned characteristics, a taxonomic review of taxa across the P-T boundary has been carried out. Four new species are described: Hindeodus pisai, H. peculiaris, Isarcicella lobata and I. inflata. Five conodont biozones are recognized: praeparvus, parvus, lobata, staeschei, isarcica and aequabilis. In the Southern Alps Hindeodus parvus, index-species for the lower limit of the Triassic, first occurs in the Tesero Member at about 1.30 m above the base of the Werfen Formation where the P-T boundary, defined by means of conodonts, has been identified. As H. parvus has been found a little below the base of the Otoceras woodwardi Zone (KOZUR, 1996) and in the upper part of the Otoceras boreale Zone (HENDERSON 1997) these can be aligned with the middle part of the Tesero Member of the Werfen Formation. REFERENCES FARABEGOLI, E., LEVANTI, D. & PERRI, M.C. 1986. The Bellerophon Formation in the Southwestern Carnia.

The boundary Bellerophon/VJerfen Formation. In: Italian IGCP 203 Group (ed.): Permian and PermianTriassic Boundary in the South-Alpine segment of the Western Tethys, Soc. Geol. It. and IGCP Proj. 203 Meeting, July 1986, Field Guidebook, 69-75, Brescia. E. & PERRI, M.C. 1998. Permian/Triassic boundary and Early Triassic of the Bulla section (Southern Alps, Italy): lithostratigraphy, facies and conodont biostratigraphy. In: M.C. Perri & C. Spalletta (Eds.), Southern Alps Field Trip Guidebook ECOS VII. Giornale di Geologia, 60, Spec. Issue, 2 9 2 - 3 1 0 .

FARABEGOLI,

HENDERSON, C.M. 1997.

Uppermost Permian conodonts and the Permian-Triassic boundary in the Western Canada Sedimentary Basin. Bulletin of Canadian Petroleum Geology, 45(4), 6 9 3 - 7 0 7 .

KOZUR, H. 1996. The Conodonts Hindeodus, Isarcicella and Sweetohindeodus in the Uppermost Permian and

Lowermost Triassic. Geologica Croatica, 49(1), 81-115. NICORA, A. & PERRI, M.C. 1999, The P/T Boundary in the Tesero section, western Dolomites (Trento). 3.3 Bio-

and chronostratigraphy: Conodonts. In: G. Cassinis et alii (eds.), Stratigraphy and facies of the Permian deposits between eastern Lombardy and the western Dolomites. Field Trip Guidebook - 23-25 September,

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1999. International field conference on "The continental Permian of the Southern Alps and Sardinia (Italy), Regional reports and general correlations'' 15-25 September 1999, Brescia, Italy. 9 7 - 1 0 0 . PERRI, M.C. 1991. Conodont biostratigraphy of the Werfen Formation (Lower Triassic), Southern Alps, Italy.

Bollettino della Societa Paleontologica Italiana, 30(1), 2 3 - 4 6 . PERRI, M.C. & ANDRAGHETTI, M . 1987.

Permian-Triassic boundary and Early Triassic conodonts from the Southern Alps, Italy. Rivista Italiana di Paleontologia e Stratigrafia, 93(3), 2 9 1 - 3 2 8 .

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PREVALENCE OF TRIASSIC LIMESTONE SEQUENCES IN NORTHERN PAKISTAN M. CRISTINA PERRI\ JOHN A. TALENT2, IRSHAD AHMAD3, AMJAD ALI3, PETER D. MOLLOY2 and PATRICK J. CONAGHAN2 1

Dipartimento di Scienze della Terra e Geologico Ambientale, University di Bologna, via Zamboni 67,140126, Italy Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia 3 National Centre of Excellence in Geology, University of Peshawar, NWFP, Pakistan

Though Triassic sequences outcrop in many areas of central Pakistan, they have been relatively neglected biostratigraphically except for the famed Permian-Triassic boundary sequences of the Salt and Surghar Ranges and, in less detail, the Kohat region (SLTHOLEY 1943; KUMMEL 1953, 1966; KUMMEL & TEICHERT 1964, 1966, 1970; BALME 1970, GRANT 1970; SARJEANT 1970; SOHN 1979; SWEET 1970; FATMI 1973, 1977; NAKAZAWA 1983,

1985; PAKISTAN-JAPANESE WORKING GROUP 1981; PAKISTAN-JAPANESE RESEARCH GROUP

1985).

Indubitable Triassic sequences are known from the Attack district (Cox 1935; FATMI 1977) and have been confirmed on the basis of conodont data from the northeastern flank of the Peshawar Basin where conodont data indicate an age-spectrum from late Famennian to Late Triassic (late Carnian) (POGUE et al 1992, 1999; IRSHAD & PERRI herein). They could well be present in the metamorphic complexes intervening between the Peshawar Basin and the Chitral and Gilgit regions of northernmost Pakistan, the focus of the present report. Thick units of limestone, often believed to be Permian (into Early Triassic), Cretaceous and possibly Jurassic, occur in many places in northern Chitral and Gilgit (cf. DESIO 1958, 1959, 1963, 1964a, 1964b; DESIO et al. 1963; DESIO & MARTINA, 1972; MATSUSHITA & HUZITA, 1985, SEARLE 1991; ZANCHI & GAETANI, 1994; GAETANI et al. 1995; GAETANI & LEVEN 1993; SEARLE & KHAN 1996). These include the indubitably Early

Cretaceous occurrences in the Yasin, Chumarkhan and Laspar valleys (DESK) 1958, 1959, 1963; DESIO et al. 1977; ZANINETTI & BRONNIMANN 1975), and the spectacular Krinj belt extending across the Kalash valleys, the Lutko valley and along the eastern flank of Ojchor Gol in Chitral (PUDSEY 1985, 1986; PUDSEY et al. 1985, 1986). Additionally there is the long-known Permian fusulinid occurrence at Rosh Gol (GAETANI & LEVEN 1993), and minor occurrences of Permian fusulinid limestones associated with faults in the Kuragh-Zait area of central Chitral (P.J. CONAGHAN unpub. data). There are also tracts of Devonian carbonates between Chilinji in the upper Karambar valley and central Chitral (TALENT et al. 1984, 1999), but these are less prominent than the salient Cretaceous/Permian limestone tracts. The proportion of carbonate units and carbonate intercalations (and the age-spectrum represented) increases from the upper Yarkhun valley eastwards to the Chapursan and Shimshal valleys of Hunza where the palaeogeographic pattern and ages of stratigraphic units are better known from conodonts, fusulinids and brachiopods (cf. GAETANI etal. 1995) Many of the limestone tracts in the Yarkhun valley may be repetitions of the Darkot Limestone of the Yasin valley, long considered to be Permian in age (IVANAC et al. 1956; PUDSEY 1985; PUDSEY & GUPTA 1986—the last with probably spurious identifications). Recent sampling has demonstrated (PERRI & ALI unpub. data) that at least part of the massive limestone unit crossing the Mastuj-Lasht road in the vicinity of Wekhcherdin, (north of Dobrargar) includes Early Triassic horizons close to the Permian-Triassic boundary. Reconnaissance sampling (P.J. CONAGHAN unpub. data) of the "Zait limestone", outcropping superbly as a mesa between Torman and Zait Gols in central Chitral, has produced conodonts likewise indicative of Early Triassic horizons close to the Permian-Triassic boundary (PERRI & MOLLOY unpub. data). What is apparently the same unit outcrops spectacularly in the vicinity of Buni (northwest of Zait) and on the left flank of the Barum Gol at Parpish. In the latter area the Chitral Slates (Permian in age; at least in part—TIPPER 1922; CALKINS et al 1981—can be seen to grade upwards into the "Parpish limestone" (TALENT et al. unpub. data). There are numerous, chronologically unconstrained or chronologically poorly constrained tracts of limestone or marble in Chitral, especially, and in northwestern Gilgit, such as the prominent Gahiret-Korghozi marble belt of central Chitral, the large limestone body of the Gazin valley, the several limestone tracts in the Yarkhun valley between Gazin and Brep, and the carbonates of the Yasin valley. Despite generally high Colour Alteration Indices (CAI), reconnaissance sampling is producing chronologically useful conodont data that will provide more precise ages for many of these units. Among these data, Triassic ages are more frequent than anticipated. Such data have potential for contributing importantly to improving understanding of the tectonostratigraphic history and palaeogeographic evolution of northern Pakistan (cf. GAETANI et al 1990, 1996; GAETANI & GARZANTI 1991; GAETANI 1997). 79

Palaeontology Down Under

Papers

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Partsan area, Hindu Kush Range, northern Pakistan. United States Geological Survey Professional Paper, 716G, 33 p. Cox, L. R. 1935. The Triassic, Jurassic and Cretaceous Gastropoda and Lamellibrancha of the Attock district. Geological Survey of India, Memoirs, Palaeontologica Indica, New Series, v. 20, Mem. 5: 27 p., 2 pis. DESIO, A. 1958. II Cretaceo fra il Karakorum e l'Hindu Kush (Asia Centrale). XXInternational Geological Congress (Mexico City), section VII: 345-354, 1 pi. DESIO, A. 1959. Cretaceous beds between Karakorum and Hindu Kush ranges (Central Asia). Rivista Italiana di Paleontologia i Stratigrafia, 65: 221-229. DESIO, A. 1963. Review of the geologic "formations" of the western Karakoram (central Asia). Rivista Italiana di Paleontologia i Stratigrafia, 69: 475-501. DESIO, A. 1964a. Geological tentative map of the western Karakoram 1: 500,000. Dipartimento di Scienze della

Terra, University di Milano. DESIO, A. 1964b. Sulla presenza del Cretaceo fossilifero nel vallone del Burji-la, presso Skardu (Baltistan, Asia

Centrale). Accademia Nazionale dei Lincei, Rendiconti, ser. 8, 37: 360-363. DESIO, A. & MARTINA, E. 1972. Geology of the upper Hunza valley, Karakorum, West Pakistan. Bolletino della Societa Geoogica Italiana, 91: 2 8 3 - 3 1 4 . DESIO, A., MARTINA, E., & GALIMBERTI, R. 1963. Notizie geologiche preliminari sull'Alta Valle di Hunza

(Karakorum-Himalaya). Accademia Nazionale dei Lincei, Rendiconti, ser. 8, 34: 1 1 5 - 1 1 7 . DESIO, A., PREMOLI SILVA, I. & Rossi RONCHETTJ, C. 1977. On the Cretaceous outcrop in the Chumarkhan and

Laspur valleys, Gilgit-Chitral, NW Pakistan. Rivista Italiana di Paleontologia i Stratigrafia, 33: 561-573. FATMI, A . N . 1973. Lithostratigraphic units of the Kohat-Potwar Province — Indus Basin, Pakistan. Pakistan

Geological Survey, Memoirs, 10: 80 p. FATMI, A . N . 1977. Mesozoic. Geological Survey of Pakistan Memoirs, 12: 29-56. GAETANI, M. 1997. The Karakoram Block in central Asia, from Ordovician to Cretaceous. Sedimentary

Geology, 109: 339-359. GAETANI, M . , ANGIOLINI, L., GARZANTI, E., JADOUL, F., LEVEN. E. Y., NICORA, A . & SCIUNNACH, D . 1995.

Permian stratigraphy in the northern Karakoum, Pakistan. Rivista Italiana di Paleontologia i Stratigrafia, 101 (2): 107-152. GAETANI, M. & GARZANTI E., 1991. Multicyclic history of the northern India continental margin (northwestern Himalaya. American Association of Petroleum Geologists, Bulletin, 75: 1 4 2 7 - 1 4 4 6 . GAETANI, M., GARZANTI, E., JADOUL, F., NICORA, A., TINTORI, A., PASINI, M . & KANWAR, S . A . K . 1990. T h e

North Karakoram side of the Central Asia geopuzzle. Geological Society of America, Bulletin, 102: 5 4 - 6 2 . GAETANI, M., LE FORT, P., TANOLI, S., ANGIOLINI, L., NICORA, A., SCIUNNACH, D. & KHAN, A . 1996.

Reconnaissance geology in upper Chitral, Baroghil and Karambar districts (northern Karakoram, Pakistan). Geologische Rundschau, 85: 6 8 3 - 7 0 4 ,

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Papers

GAETANI, M. & LEVEN, E. 1993. Permian stratigraphy and fusulinids from Rosh Gol (Chitral, E Hindu Kush). Rivista Italiana di Paleontologia i Stratigrafia, 99: 307-326. GRANT, R. E. 1970. Brachiopods from Permian-Triassic Boundary beds and age of Chiddru Formation, West

Pakistan. In: . B. Kummel, & C. Teichert, (eds). Stratigraphic boundary problems, Permian-Triassic of West Pakistan. University of Kansas, Geology Department, Special Publications, 4: 117-151.

I VAN AC, J. F., TRAVES, D. M & KING, D. 1956. The geology of the N.W. Portion of the Gilgit Agency. Geological Survey ofPakistan, Records, 8 (2): 3-26. KUMMEL, B. 1953. Lower Triassic Salt Range nautiloids. Museum of Comparative Zoology, Harvard University,

Breviora, 20: 8 p.

KUMMEL, B. 1966. The Lower Triassic formations of the Salt Range and Trans-Indus ranges, West Pakistan. Museum of Comparative Zoology, Harvard University, Bulletin 134, 361-429. KUMMEL, B., & TEICHERT, C. 1964. The Permian-Triassic boundary in the Salt Range of West Pakistan. In: Palaeontology and Stratigraphy, Report of the International Geological Congress, 22 (8): 143-156. KUMMEL, B. & TEICHERT, C. 1966. Relation between the Permian and Triassic formations in the Salt Range and

Trans-Indus Ranges, West Pakistan. Neues Jahrbuch fur Geologie und Palaontologie, Abhandlungen, 125: 297-333.

KUMMEL, B. & TEICHERT, C. 1970. Stratigraphy and palaeontology of the Permian - Triassic boundary beds,

Salt Range and Trans-Indus Ranges, West Pakistan. In: B. Kummel, & C. Teichert, (eds.), Stratigraphic boundary problems, Permian-Triassic of West Pakistan. University of Kansas, Geology Department, Special Publication, 4: 1-110.

MATSUSHITA, S. & HUZITA, K. (eds.) 1985. Geology of the Karakoram and Hindukush: Results of the Kyoto

University Scientific Expedition (1955), 161 p. Kyoto University, Japan.

NAKAZAWA, K. 1983. On the Permian-Triassic boundary in the Salt Range region, Pakistan. Kashmir Journal of Geology, 1(1): 51-54. NAKAZAWA, K. 1985. The Permian and Triassic systems in the Tethys—their paleogeography, 93-114. In: K.

Nakazawa, & J.M. Dickins, (eds.), The Tethys - her Palaeogeography and Palaeobiogeography from Palaeozoic to Mesozoic. Tokai University.

PAKISTANI-JAPANESE RESEARCH GROUP 1985. Permian and Triassic systems in the Salt Range and Surghar

Range, Pakistan. In: K. Nakazawa, & J.M. Dickins, (eds). The Tethys, her palaeogeography and palaeobiogeography from Paleozoic to Mesozoic. Tokai University Press, 221-321.

PAKISTAN-JAPANESE WORKING GROUP 1981. Stratigraphy and correlation of the marine Lower Triassic in the

Surghar Range and Salt Range, Pakistan. Memoirs of the Faculty of Science Kyoto University, Series Geology and Mineralogy, 25 p.

POGUE, K. R. & HUSSAIN, A. 1986. New light on the stratigraphy of Nowshera area and the discovery of Early

to Middle Ordovician trace fossils in NWFP, Pakistan. Geological Survey of Pakistan, Information Release, 135, 15 p.

POGUE, K. R., HYLLAND, M. D., YEATS, R. S., KHATTAK, W. U. & HUSSAIN, A. 1999. Stratigraphic and

structural framework of Himalayan foothills, northern Pakistan. Geological Society of America, Special Paper, 328: 257-274.

POGUE, K. R. WARDLAW, B. R., HARRIS, A. G. & HUSSAIN, A. 1992. Palaeozoic and Mesozoic stratigraphy of

Peshawar Basin, Pakistan: correlations and implications. Geological Society America, Bulletin, 104: 915-

927.

PUDSEY, C.J. 1985. Geology of Chitral and western Gilgit. Transactions of the Royal Society of Edinburgh, 76:

463-479.

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PUDSEY, C., COWARD, M . P., LUFF, I. W . , SHACKELTON, R. M., WINDLEY, B. F. & JAN, M . Q . 1985. Collision

zone between the Kohistan arc and the Asian plate in NW Pakistan. Transactions of the Royal Society of Edinburgh, Earth Sciences, 76: 4 6 3 - 4 7 9 . PUDSEY, C. J. & GUPTA, V. J. 1986. Palaeozoic fossils from Kohistan, 208-211. Geology of western Himalaya

(Contributions to Himalayan geology, v. 3). Hindustan, New Delhi. [Note: Because of plethora of spurious reports by V.J. Gupta, these lists should be ignored or regarded with extreme caution] PUDSEY, C. J., SCHROEDER, R. & SKELTON, P. W . 1986. Cretaceous (Aptian/Albian) age of island-arc volcanics,

Kohistan, N Pakistan, 150-168. Geology of Western Himalaya (Contributions to Himalayan Geology, v. 3). Hindustan, New Delhi. SARJEANT, W.A.S. 1970. Acritarchs and tasmanitids from the Chhidru formation, uppermost Permian of west

Pakistan. In: B. Kummel, & C. Teichert, (eds), Stratigraphic Boundary Problems. Permian and Triassic of West Pakistan. University of Kansas, Geology Department, Special Publication, 4 , 2 7 7 - 3 0 4 . SEARLE, M. P. 1991. Geology and tectonics of the Karakoram Mountains, 358 p., John Wiley & Sons, Oxford. SEARLE, M. P. & KHAN, A. (eds) 1996. Geological map of north Pakistan, 1:650,000. Blackwell, Oxford.

R. V. 1943. Plant-remains from the Triassic of the Salt Range. Indian Academy of Science, Proceedings, 13: 300-327.

SLTHOLEY,

SOHN, I. G. 1970. Early Triassic marine ostracodes from the Salt Range and Surghar Range, West Pakistan. In:

B. Kummel, & C. Teichert, (eds.), Stratigraphic boundary problems, Permian and Triassic of West Pakistan). University of Kansas, Geology Department, Special Publication, 4: 193-206. SWEET, W. C.

1970. Uppermost Permian and Lower Triassic conodonts of the Salt Range and Trans-Indus Ranges, West Pakistan. In: Stratigraphic Boundary Problems; Permian and Triassic of West Pakistan. In: B. Kummel, & C. Teichert, (eds.), University of Kansas, Geology Department, Special Publication, 4: 207-276.

TALENT, J. A„ CONAGHAN, P. J., MAWSON, R., MOLLOY, P. D. & PICKETT, J. W . 1982. Intricacy of tectonics in

Chitral (Hindu Kush): Faunal evidence and some regional implications. Himalayan Geology Seminar (1976), section II A, Geological Survey of India, Miscellaneous Publications, 41: 77-101. TALENT, J. A., GAETANI, M . , MAWSON, R., MOLLOY, P. D., & CONAGHAN, P.J. (with a contribution from O.

Lehnert & J.A. Trotter). 1999. Early Ordovician and Devonian conodonts from the western Karakoram and Hindu Kush, northernmost Pakistan. Rivista Italiana di Paleontologia i Stratigrafia, 105: 201-230. TALENT, J. A., & M AWSON, R. 1979. Paleozoic-Mesozoic biostratigraphy of Pakistan in relation to biogeography and the coalescence of Asia, 8 1 - 1 0 2 . In: A. Farah. & K.A. De Jong (eds), Geodynamics of Pakistan,

Geological Survey of Pakistan, Quetta. TIPPER, G. H. 1922. [Chitral]. In: L.L. Fermor, General report for 1921. Geological Survey of India, Records, 54, pt 1, 5 5 - 5 7 . TIPPER, G. H. 1924. [Chitral]. In: E.H. Pascoe, General report for 1923. Geological Survey of India, Records, 56, pt 1 , 4 4 - 4 8 . ZANCHI, A. & GAETANI, M. 1994. Introduction to the geological map of the North Karakoram Terrain from the Chapursan valley to the Shimshal Pass 1:150,000 scale. Rivista Italiana di Paleontologia i Stratigrafia, 100: 125-136.

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Papers

HIGH RESOLUTION GRAPTOLITE BIOSTRATIGRAPHY BARRANCOS REGION, SOUTH PORTUGAL

IN THE SILURIAN

OF THE

JOSE MANUEL PigARRA

Instituto Geologico e Mineiro, Ap. 104,7802, Beja codex, Portugal, iose.picarra@igm.pt The Silurian succession of the Barrancos region is within the Ossa Morena Zone, a major tectono-stratigraphic unit of the Hesperian Massif (SW of the Iberian Variscides). It corresponds to a condensed sequence, with a maximum thickness of about 80 m, where, up to now, 19 graptolite biozones (figure 1) have been identified (GUTIERREZ-MARCO et al. 1998; ROBARDET etal 1998). The lower part of the succession includes at least the uppermost quartzites of the Colorada Formation and the 5 to 8 m of alternating black shales and lydites of the "Xistos com N6dulos" Formation, that correspond to the interval between the Rhuddanian Parakidograptus acuminatus and the Aeronian Lituigraptus convolutus biozones. This is followed by 20-25 m of black shales with rare lydite levels (middle and upper parts of the "Xistos com N6dulos" Formation) that have yielded graptolites of the interval between the Telychian Rastrites linnaei and the Ludfordian Saetograptus leintwardinensis biozones.

Pridoli

Barrancos Portugal bouceki

dCO

parultimus

Vallc sync. Spain

trans grediens

Central Iberian Z. Spain

ultimusparultimus

Ludlow

•8 ?kozlowskii 3 ?lcintwardincnsis leintwardinensis -J

Wenlock | Homerian |

k-4 <3

a '-9 *8

scanicus nilssoni In den sin ? parvus-nassa lundgrcni ?pcrncri Vbclophorus ? murchisoni

Llandovery | Aeronian

G ? d § spiralis tullbergi &o gricstonicnsis >> ens pus r—• turriculatus

tncipienstumescens nilssoni ludensis dcubclipracdcubcli parvus-nassa lundgrcni .? ?rigidus

?grandis spiralis ?tullbergi

? ?

linnaei

convolutus

? ?

triangulates

d cyphus i vesiculosus acuminatus

linearis scanicus progenitor nilssoni ludensis-gerhardi dcubclipracdeubeli parvus-nassa ,lundgreni testis . "lundgrcni" rnHian* cllesac-ramosus rigidus ?

hrtnf^inrm hHnphnni riiihiu*s heldiniphnrm hni* nccartnncnsis "murchisoni" murchisoni

turriculatus linnaei sedgwickii

Bohemia

transgrediens bouceki lochkovensis pridoliensis ultimusparultimus fragmcn talis ko7lowskn in ex pec talus

? cyphus

centrifugus inscctua grandis lafe^vorthi spiralis spiralis tullbergi tullbergi gricstonicnsis gricstonicnsis enspus arcuatus turriculatus turriculatus hispanicus hispanicus linnaei linnaei naTmeus sedgwickii

Tmwrirtnii ?

convolutus simulans pectinatus -triangularis normalog raptids cyphus

vesiculosus -acuminatus ascensus

British Isles

Arctic Canada

tramgredtens p. bouceki chelmiensis u Him us formosus

Bohemograptus bohemicus tenuis leintwardinensis linearis lmcipiensumMcens nilssoni ludensis nassa lundgreni ellesae flcxilis rwidup riccartonensis murchisoni centrifugus

progenitor ludensis deubelipracdeubeli dubius-nassa testis lundgreni WnUi Dvmcn kolobusinstrenuus centrifugus

ioasfitua

sakmaricus crenu^ata griestoniensis enspus turriculatus maximus sedgwickii convolutus leptothoca ma gnus triangulatus cyphus acinaccs atavus acuminatus

griestoniensis enspus turriculatus guerichi ? convolutus orbitus pectinatus cyphus acinaces atavus ninu/injL mademu Tiihrir.nt

Fig. 1. Silurian graptolite biozonal correlation chart of some world regions This black shale sequence is overlain by dark shales and siltstones (30-40 m) of the "Xistos Raiados" Formation, that yielded graptolites of the interval between the Ludfordian Saetograptus leintwardinensis and the Pridoli Monograptus bouceki biozones. The uppermost part of this succession is already of Lochkovian age, as attested by the presence of Monograptus uniformis.

Papers

Palaeontology Down Under

The Llandovery euxinic sedimentation begins at the base of the P. acuminatus Biozone (PLQARRA et al. 1995) with few biserial taxa (Parakidograptus, Normalograptus, Cystograptus and Neodiplograptus). The maximum species diversity (16) was attained in the Aeronian Lituigraptus convolutus Biozone. A break-down of the assemblage occurs from the upper Aeronian, when many lineages disappeared, such as the biserial genera Normalograptus, Pseudorthograptus and Neodiplograptus, as well as the monograptids Campograptus and Coronograptus. This apparent decrease in taxonomical diversity was probably related to the Convolutus extinction Event (&TORCH 1995). The Telychian graptolite faunas are poorly diversified, with a graptolite record in the Spirograptus turriculatus and Torquigraptus tullbergi biozones restricted to the respective zonal-index species. Streptograptus crispus is present in the Barrancos region and this species is very rare in the other parts of the Hesperian Massif. The oldest Wenlock assemblages have a greatly impoverished fauna, just with the characterization of the early Sheinwoodian Cyrtograptus murchisoni Biozone. The lower Homerian is represented by the Cyrtograptus lundgreni Biozone, with 7 graptolites species associated with some benthic fauna. This includes the outstanding record of articulate hexactinellid sponges, collected just below an orange-coloured band that marks the Lundgreni Event of graptolite extinction (GUTISRREZ-MARCO et al 1996). This particular bed is also known from Spain and corresponds with a minimum diversity of graptolite assemblages, restricted to the opportunistic taxa Pristiograptus parvus and Gothograptus nassa, and being coincident with the extinction of the genera Cystograptus, Testograptus and the temporary disappearance of the genus Monograptus s.s. In the Valle syncline (Spanish part of the Ossa Morena Zone) similar sponges occur within a yellow horizon at the top of the Cyrtograptus lundgreni Biozone, The sponge assemblages from the southwestern Iberian Silurian can be related thus to the environmental changes that involved and immediately preceded the Lungreni extinction Event (RlGBY et al 1997). The remaining part of the black shale sequence yielded graptolites of the Homerian Colonograptusl ludensis Biozone and of the Gorstian Neodiversograptus nilssoni and Lobograptus scanicus biozones. In the Barrancos region a change in the environmental conditions began in the upper Ludlow with the occurrence of alternations of dark shales and siltstones, that characterized the overlying Xistos Raiados Formation. This type of succession is rarely recorded in the northern peri-Gondwana domain and within the Iberian Peninsula occurs only in the Palentian region, northern Spain. Usually, in these terrigenous alternations the occurrence of pelagic faunas is almost exceptional, but the Barrancos succession yielded graptolites from the Ludfordian Saetograptus leintwardinensis-Neocucullograptus kozlowskii interval, succeeded by other Pridoli assemblages of the Neocolonograptus parultimus and Monograptus bouceki biozones (PLQARRA et al 1998). A moderate diversity of the upper Ludlow-Pridoli graptolite assemblages of the Barrancos region suggests that the deep-water conditions must have prevailed during this time interval, but a transition to a shallower shelf environment cannot be excluded. Biostratigraphy and palaeoenvironmental data from the Silurian sequence from Barrancos appear similar to those of the North Gondwanan regions of Europe where pelagic facies developed, as in SW Spain (Valle syncline), Bohemia, Germany and Sardinia, except for the absence of the Ludlow and Pridoli limestones. However, the graptolite assemblages from southern Portugal, are considerably less diverse than in these regions. The Barrancos region is clearly integrated within the cool-water Graptolite Province of the peri-Gondwanan Europe (§TORCH 1998). REFERENCES Wenlock-Ludlow graptolite biostratigraphy and extinction: a reassessment from the southwestern Iberian Peninsula (Spain and Portugal). Canadian Journal of Earth Sciences, 33: 656-663.

GUTI£RREZ-MARCO, J.C., LENZ, A., ROBARDET, M . & PICARRA, J.M. 1996.

GUTIERREZ, J.C., ROBARDET, M . & PIQARRA, J.M.. 1998.

Silurian stratigraphy and paleogeography of the Iberian Peninsula (Spain and Portugal). Temas Geologico-Mineros ITGE, 23:13-44.

Papers

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STORCH, P. GUTIERREZ-MARCO, J.C. & OLIVEIRA, J.T. 1995. Characterization of the Parakidograptus acuminatus graptolite Biozone in the Silurian of the Barrancos region (Ossa Morena Zone, South Portugal). Communicacoes de Institute Geologicoe Mineiro., 81: 3-8.

PICARRA, J.M,

PIQARRA, J.M., GUTIERREZ-MARCO, J. C., LENZ, A. C. & ROBARDET, M . 1998. Pridoli graptolites from the

Iberian Peninsula: a review of previous data and new records. Canadian Journal of Earth Sciences, 35: 6575. RIGBY, J.K., GUTIERREZ-MARCO, J.C., ROBARDET, M . & PIQARRA, J.M. 1997. First articulated Silurian sponges

from the Iberian Peninsula (Spain and Portugal). Journal of Paleontology, 71 (4): 554-563. ROBARDET, M., PIQARRA, J.M., STORCH, P. GUTI6RREZ-MARCO, J.C. & SARMIENTO, G.N. 1998. Ordovician and

Silurian stratigraphy and faunas (graptolites and conodonts) in the Ossa Morena Zone of the SW Iberian Peninsula (Portugal and Spain). Temas Geologico-Mineros ITGE, 23: 289-318. STORCH, P. 1995. Biotic crises and post-crisis recoveries recorded by Silurian planktonic graptolite faunas f the Barrandian area (Czech Republic). Geolines, 3: 59-70. §TORCH, P.

1998. Biostratigraphy, paleobiogeographical links and environmental interpretation of the Llandovery and Wenlock graptolite faunas of peri-Gondwanan Europe. Temas Geologico-Mineros ITGE, 23: 126-129.

Papers

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FIRST EVIDENCE OF THE BASAL LLANDOVERY (PARAKIDOGRAPTUS GRAPTOLITE BIOZONE) IN THE ARMORICAN MASSIF (WESTERN FRANCE)

ACUMINATUS

JOSE MANUEL PI^ARRA 1 , MICHEL ROBARDET 2 , FLORENTIN PARIS 2 ,HUBERT LARDEUX 2 and JUAN CARLOS GUTIERREZ-MARCO 3 1

Instituto GeoI6gico e Mineiro, Ap. 104,7802, Beja codex, Portugal GSosciences Rennes (UPR 4661 CNRS), University de Rennes 1, Campus Beaulieu, F-35042 Rennes cedex, France 3 Instituto de Geologfa Econ6mica (CSIC-UCM), 28040, Madrid, Spain 2

Graptolite assemblages indicative of the basal Silurian Parakidograptus identified in two localities of the Armorican Massif of western France.

acuminatus Biozone have been

The Gouarec locality (fig. 1-A) is situated in the southeastern part of the Chateaulin synclinorium, a major structure of the Mid-North Armorican Domain (MNAD). In this locality, the Silurian succession comprises, in ascending order, two informal lithological units (cf. SAGON 1976; DADET et al. 1988): the "Lower Silurian Quartzites" and the "Middle and Upper Silurian Shales". The upper unit can be divided into: a) lower shales, b) ampelitic black shales, and c) alternating shales and quartzites; and is overlain by a very thick (up to 700 m) unit of chloritoid shales of "Siluro-Devonian" age. The only fossils found in this succession were "Monograptus" cf. dubius from the ampelitic black shales, and "Monograptus" roemeri from the alternating shales and quartzites (PHILIPPOT 1950), and the biostratigraphical assignments were rather unprecise. "Poorly preserved graptolite faunas of early Rhuddanian affinities" have been recently mentioned by PARIS

(2000). The new fossiliferous level occurs within the uppermost part of the "Lower Silurian Quartzites"; it corresponds to dark grey, impure and micaceous quartzites, becoming white when weathered, that crop out on the northern side of the road RN 164, between Caurel and Gouarec. The graptolitic fauna is poorly preserved. However, it has been possible to identify Parakidograptus acuminatus, Cystograptus ancestral is, Neodiplograptus cf. lanceolatus and Normalograptus sp., a typical assemblage of the Parakidograptus acuminatus Biozone.

Fig. 1. Geographic distribution of Palaeozoic strata (dotted areas) in the Armorican Massif, with location of the studied graptolitic localities (*). A - Gouarec, B - Chalonnes-sur-Loire The second locality, Chalonnes-sur-Loire (fig. 1-B) is situated in the southeastern part of the Armorican Massif, within the Ancenis unit of the Ligerian Domain. The lower Palaeozoic rocks of this domain, including the Silurian, constitute rather discontinuous outcrops that probably correspond to exotic blocks (olistolites and 86

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olistostromes) redeposited within an early Carboniferous basin (DUBREUIL 1980). The Silurian of the Ligerian Domain is characterized by the so-called "phtanites" that correspond to black microquartzites (or black cherts) which do not exist in the Silurian of the MNAD. The rest of the succession is poorly known, with rare and local occurrences of Wenlock shales with Monograptus latus, and Ludlow shales and limestones with "Monograptus" nilssoni (CAVET et al 1971). In the area of Chalonnes-sur-Loire, the phtanites yielded rich graptolite assemblages. The most recent revision of the fauna was made by PHILIPPOT (1950) who listed 17 species of Aeronian and basal Telychian ages. The new data come from a trench within an "industrial" and commercial area recently established to the southeast of Chalonnes. The studied section shows about 10 m of thin-bedded phtanites with intercalated black shales and the contact with the "underlying" (apparently overlying, due to the inverted dips) rocks which appear as brown siltstones with dispersed fragments and quartz grains, a typical facies of the Hirnantian glaciomarine sediments that characterize the uppermost Ordovician of the Armorican Massif and other north Gondwanan regions where they have been dated (PARIS et al. 1995). The fossiliferous level, found 40-80 cm above the base of the phtanites, has yielded Akidograptus ascensusl, Parakidograptus acuminatus, Normalograptus trifilis, Normalograptus normalis, Neodiplograptus cf. elongatus, Neodiplograptus lanceolatus and Glyptograptus sp. The present evidence of the P. acuminatus Biozone in two localities of the Armorican Massif, is remarkable in several aspects: - The base of the Silurian System is clearly identified for the first time in the Armorican Massif. Previous studies in the Domfront area (Southern Normandy, MNAD, see fig. 1) had mentioned the occurrence of "Climagraptus scalaris normalis" and "Orthograptus truncatus var. abbreviates" in the uppermost levels of a quartzitic unit, but the stratigraphical conclusions were uncertain (PHILIPPOT & ROBARDET, 1971). - Up to now it was generally considered that the Ordovician and the Silurian were separated by a hiatus, corresponding to the early Llandovery and probably related with the eustatic effects of the late Ordovician glaciation. - Both the graptolite assemblages and the facies development can be well compared with other basal Silurian successions throughout north Gondwanan Europe, namely from Portugal, Spain, Sardinia, Bohemia, Germany, Carnic Alps, Eastern Serbia and Bulgaria. ACKNOWLEDGMENTS This work was carried out within a French-Portuguese co-operation project (061 BO, Ambassade de FranceICCTI). It is also a contribution to IGCP project 410 (The Great Ordovician Biodiversification Event) and to the French CNRS CRISEVOLE project. REFERENCES CAVET, P., LARDEUX, H. & PHILIPPOT, A. 1971. Ordovicien et Silurien aux environs de Montjean et Chalonnes

(Maine-et-Loire, Sud-Est du Massif Armoricain). Memoires du Bureau de Recherches Geologiques et Minieres, 73: 199-212, Orleans. DADET, P., BOS, P., CHANTRAINE, J., LAVILLE, P. & SAGON, J.P. 1988. Notice explicative de la feuille Pontivy &

1/50.000 (n° 313). Bureau de Recherches Geologiques et Minteres, 77p., Orleans. DUBREUIL, M. 1980. Hypothdse sur la mise en place, au Dinantien, du complexe du Tombeau Leclerc (Bassin

d'Ancenis, sud-est du Massif armoricain) sous forme d'un olistostrome. Consequences gdodynamiques. Comptes Rendus de I'Academie des Sciences, Paris, s£rie D, t. 290: 1455-1458. PARIS, F. 2000. Silurian of France. In: J. Kriz (coord.) Silurian stratigraphy and paleogeography of north

Gondwanan and Perunican Europe. Second volume of the James Hall Symposium, E. Landing, (ed.), New York State Bulletin (in press). F., ELAOUAD-DEBBAJ, Z., JAGLIN, J.C., MASSA, D. & OULEBSIR, L. 1995. Chitinozoans and Late Ordovician glacial Events in Gondwana. pp. 171-176 In: J.D. Cooper., M.L. Droser & S.C. Finney, (eds.) Ordovician Odyssey, Pacific Section Society for Sedimentary Geology, Fullerton, California, USA.

PARIS,

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PHIUPPOT, A. 1950. Les Graptolites du Massif Armoricain. Etude stratigraphique et pateontologique. Memoires de la Societe geologique et mineralogique de Bretagne, 11: 1-295, Rennes. PHILIPPOT, A. & ROBARDET, M. 1971. Nouvelles donntes sur les formations siluriennes de Domfront (Orne). Bulletin de la Societe geologique et mineralogique de Bretagne, s6rie C, t. Ill, 2: 41-47, Rennes. SAGON, J.P. 1976. Contribution & I'&ude geologique de la partie orientale du bassin de Chateaulin (Massif armoricain): stratigraphie, volcanisme, m6tamorphisme, tectonique. Doctoral thesis, University Pierre et Marie Curie, Paris VI, 671 p. (unpublished).

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ORDOVICIAN FAUNAS AND BIOSTRATIGRAPHY IN THE GUNNINGBLAND AREA, CENTRAL NEW SOUTH WALES JOHN PICKETT and IAN G. PERCIVAL Specialist Services Section, Geological Survey of New South Wales, PO Box 76, Lidcombe NSW 2141, Australia The Billabong Creek Limestone and overlying Gunningbland Formation within the Northparkes Group in the Gunningbland area, 28 km west of Parkes, range in age from late Darriwilian (late Middle Ordovician) to late Eastonian (middle Late Ordovician). These strata provide the most complete sequence through this interval in the central Lachlan Orogen in New South Wales. Two sections have been examined in detail, together comprising a stratigraphic thickness of the order of 1600 m. Correlation between the two sections is provided by deeper water strata with brachiopods, graptolites and the trilobite Parkesolithus gradyi CAMPBELL & DURHAM. A precise age (Da4) for the base of the Billabong Creek Limestone is provided by the zonal conodont Pygodus anserinus LAMONT & LLNDSTROM, which occurs in a thin oncolitic and oolitic limestone with much sediment of andesitic volcanic origin. Below this horizon outcrops are poor, but isolated conodont samples have yielded inter alia the conodont Pygodus anitae BERGSTROM, implying the presence of even older strata, still of Darriwilian age. A biostratigraphic zonation spanning the Darriwilian to Gisbornian interval is proposed, employing conodonts and corals, which supplements the existing coral/stromatoporoid faunal assemblages defining Eastonian and Bolindian shelly fossil zones. The oldest zone recognized is the Foerstephyllum-Billingsaria-Stratodictyon Assemblage Zone (Gisbornian), characterized by the first appearance of Foerstephyllum, Tetradium and Stratodictyon, with Billingsaria a conspicuous faunal element. The type area for this zone lies in the lower limestone of the type section of the Billabong Creek Limestone. New species of Foerstephyllum, Billingsaria and Lichenaria are described from this level. This is followed by the Hillophyllum-Tetradium-Rosenella Assemblage Zone (equivalent to coral/stromatoporoid fauna I of Webby), represented in the upper part of the Billabong Creek Limestone in the type section by an assemblage including all nominate genera, though Tetradium does not show the acme typical of this level elsewhere. Near the Billabong Creek road crossing, where the limestones are disturbed structurally, there are assemblages typical of the next level, the ProporaEcclimadictyon-Cliefdenella Assemblage Zone (= coral/stromatoporoid fauna II of Webby). In the extension of the type section on New Durran station, where the sedimentary facies becomes typical of deeper water, this fauna also occurs in a slump breccia in the Gunningbland Formation with limestone boulders yielding species typical of this level (Pseudostylodictyon inequale WEBBY, Ecclimadictyon nestori WEBBY, Propora mammifera HILL), as well as a new genus of conodont (described elsewhere), which appears to be useful biostratigraphically, and the diagnostic species Taoqupognathus blandus An, indicative of an Ea2 age. Overlying shales about 50 m above the slump conglomerate yield a rich brachiopod-trilobite assemblage, which is the type area for the Anomaloglossa-Durranella-Parkesolithus Assemblage Zone; a few metres above this level the shales contain a graptolite faunule regarded as Ea3 in age. North of the Parkes-Broken Hill railway line this level can again be recognized, and the section continues to the west. One hundred metres further west, north of Sunnyside station homestead is a richly fossiliferous red limestone with an assemblage including Plasmoporella inflata HILL, Palaeophyllum jugatum MCLEAN & WEBBY and Cliefdenella perdentata WEBBY & MORRIS, forms which are characteristic of the FavistinaHalysites-Plasmoporella Assemblage Zone (= coral/stromatoporoid fauna III of Webby), though halysitids have not yet been recovered in this area. This horizon also yields the conodont Taoqupognathus tumidus TROTTER & WEBBY.

West of this there is some faulting, separating the continuous section from a small syncline on Currajong Park station. The oldest beds cropping out here are limestones with macrofossils of the Favistina-HalysitesPlasmoporella Assemblage Zone and the conodont Taoqupognathus tumidus, overlain immediately by tuffaceous sandstones and shales containing the brachiopods Casquella bifida PERCIVAL, IDulankarella partita PERCIVAL, Gunningblandella resupinata PERCIVAL, IScaphorthis aulacis PERCIVAL, Sowerbyella anticipata PERCIVAL, Infurca tessellata PERCIVAL, Kassinella anisa PERCIVAL and Sowerbyites vesciseptus PERCIVAL, together with a diverse assemblage of undescribed trilobites. This is the type area for the GunningblandellaKassinella- 'Illaenus' Assemblage Zone.

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On the western side of this syncline is the youngest limestone known from the Gunningbland Formation, interpreted as a pinnacle reef and yielding Palaeophyllum jugatum, Plasmoporella inflata, and the conodont Taoqupognathus tumidus, indicating a level not greatly different from the limestone on the eastern side. Fine sandy sediments adjacent to and overlying this limestone have yielded a graptolite faunule regarded as Ea3/4 in age, and which represent the youngest fossiliferous strata recognized. Surrounding the limestone of the pinnacle reef are clastic sediments containing brachiopods which decrease in size as progressively deeper water depositional environments are encountered. In order of increasing depth, these are a Sowerbyites assemblage, a Gunningblandella assemblage and finally Kassinella associated only with graptolites. [Published with the permission of the Director General, NSW Department of Mineral Resources. This is a contribution to IGCP 410 "The Great Ordovician Biodiversification Event".]

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LATE ORDOVICIAN BRACHIOPOD MASS EXTINCTION AND SUBSEQUENT RECOVERY IN SOUTH CHINA RONG JIA-YU1, D. A. T. HARPER2, and ZHAN REN-BIN1 1

Nanjing Institute of Geology and Palaeontology, Academia Sinica, Chi-Ming-Ssu, Nanjing 210008, China Geological Museum, University Copenhagen, Oster Voldgade 5-7,1350 Copenhagen K, Denmark

Based on new investigations of taxonomic data of 130 brachiopod genera assigned to 13 orders and 27 superfamilies from the mid Ashgill through the late Aeronian interval in South China, brachiopod macroevolution before and after the latest Ordovician mass extinction is signaled by significant changes in diversity, compositions and stratigraphical distribution of brachiopod faunas. I. Foliomena Fauna. Recently, extensive new data on deeper water brachiopod assemblages of late Ordovician age have been assembled from South China. It was known that both the typical Foliomena fauna commonly characterized by Foliomena, Dedzetina, Leptestiina, Christiania and Cyclospira, and the Foliomena-bearing fauna represented by Foliomena and a variety of the other taxa are well developed in South China in late Ordovician (Caradoc to mid Ashgill). More data indicate that Foliomena first occurred in the Miaopo Formation (early Caradoc), the typical Foliomena fauna appeared in the Lower part of the Pagoda Formation (mid Caradoc), and extended to the Linhsiang Formation (early Ashgill) in the Yangtze region and Huangnekang Formation (early Ashgill) in the Jiangnan region. The black graptolite shale (Wufeng Formation) was widely distributed on the Yangtze Platform but lacked a Foliomena fauna, although Foliomena and Christiania occur in the Changwu Formation of the Jiangnan region during the mid Ashgill time. II. Altaethyrella Fauna. The mid Ashgill is considered the last radiation interval before the latest Ordovician mass extinction. The Xiazhen Formation (mid Ashgill) yields many shallow water (chiefly BA2-3) assemblages with relatively higher diversities. They include many taxa of nonarticulates (Acanthocrania, Ectenoglossa, Pectoglossa, Peritrimerella), dalmanelloids (Glyptorthis, Plectorthis, Ptychopleurella, Mimella, Skenidioides, Plectorthis, Epitomyonia, Onniella, Wangyuella) and strophomenoids (Triplesia, Oxoplecia, Reversella, Bimuria, Kassinella, Synambonites, Metambonites, Rongambonites, Sowerbyella, Rugosowerbyella, Strophomena, Katastrophomena, Fenomena, Holtedahlina, Tashanomena, Leptaena, Eopholidostrophia, Christiania, Fardenia, very rare Foliomena), associated with pentameroids (.Eosotrophia, Parastrophinella, Brevilamnulella, Tcherskidium), rhynchonelloids (Altaethyrella), atrypoids (Antizygospira, Ovalospira, Spirigerina), and spiriferoids (Eospirifer). The Foliomena fauna disappeared in South China in the late mid Ashgill owing to local tectonic uplift, and became extinct at the end of mid Ashgill due to the initial effects of the latest Ordovician (Hirnantian) glaciation, suggesting the first phase of the latest Ordovician mass extinction. III. Hirnantia Fauna. Successively, the Wufeng Formation with deeper, probably desalinized, and dysoxic marine environments is stratigraphically overlain by the Kuanyinchiao Beds (late Ashgill) with shallow water typical, cool Hirnantia fauna which occurs extensively across the Yangtze region. The late Ashgill includes the Normalograptus extraordinarius zone and lower Normalograptus persculptus zone and is a faunally depleted interval following the first phase of the mass extinction. In this fauna are genera of nonarticulates (Lingulella, Acanthocrania, Philhedra, Orbiculoidea, Trematis, Pseudopholidopsis), dalmanelloids (Dalmanella, Onniella, Trucizetina, Dysprosorthis, Mirorthis, Draborthis, Hirnantia, Kinnella, and Drabovinellal) and strophomenoids (Aegiromena, Leptaena with Leptaenopoma, Eostropheodonta, Fardenia or Coolonia, Triplesia, Cliftonia, Onychoplecia), along with a few orthoids (Toxorthis), rhynchonelloids (Dorytreta, Plectothyrella, Sphenotreta) and athyridoids {Hindella or Cryptothyrella, Whitfieldella). The first phase of the latest Ordovician mass extinction evidently led to a decrease in brachiopod diversity, and a replacement of the shallow water Althaethyrella fauna and deeper water Foliomena fauna in the mid Ashgill by the Hirnantian fauna in the late Ashgill. The rate of speciation of the Hirnantia fauna is relatively rapid and can be compared to that during the early Silurian recovery interval. The Hirnantian, therefore, has been considered a survival-recovery time interval following the first phase of the mass extinction. The Hirnantia fauna became extinct near the end of late Hirnantian due to a rapid sea level rise producing anoxic conditions, coincident with the second phase of the latest Ordovician mass extinction. IV. The latest Ashgill, very late Hirnantian (Normalograptus persculptus zone) to very early Rhuddanian, and Llandovery is a short bleak, early survival interval following the mass extinction. Recent investigation on the section across the Ordovician-Silurian boundary at Honghuayuan, south of Tongzi County, northern Guizhou, South China indicates that some common taxa in the typical Hirnantia fauna (Pseudopholidopsis, Paromalomena, Eostropheodonta, Plectothyrella and Hindella) occur in shelly beds of very early Rhuddanian 91

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strata immediately above the Hirnantia-bemng fauna. Paromalomena and Plectothyrella were known only in the Ordovician, whereas Pseudopholidopsis, Eostropheodonta and Hindella were known to extend to the Silurian. It seems to the authors that the latter three are regarded as survivors following the latest Ordovician mass extinction. It should be noted, furthermore, that the Hirnantia fauna generally lacks pentameroids, atrypoids, and spiriferoids, three of the major brachiopod groups in the recovery following the second phase of the latest Ordovician mass extinction. A few specimens of Eospirigerina (atrypoids) were found in the Hirnantia fauna of Tibet, and have not been known in the same fauna elsewhere. V. Alispira Fauna. Only near shore, low-diversity, benthic assemblages (chiefly BA 2), characterized by most Ordovician relicts, are known from the southern marginal area of the Upper Yangtze epicontinental sea in earlymid Rhuddanian. This is a later survival interval from the mass extinction. During this survivor interval brachiopods are characterized by near shore, shallow water assemblages with a low diversity. The most abundant brachiopods, Alispira (atrypoid) and Eospirifer (spiriferoids), are recognized as disaster taxa typically known from the Wulipo Bed at Gouliantian, Wulipo, northwest of Meitan County, northern Guizhou. They are associated with a few specimens of orthoids (Dolerorthis, Dalmanella, Levenea, Mendacella), strophomenoids {Fardenia or Coolonia), rhynchonelloids (Rostricellula), atrypoids (Eospirigerina), and common Hindella (athyridoids). The latter three (jDalmanella, Fardenia, and Hindella) may be considered the survivors extending from the Hirnantia fauna, Dolerorthis the Lazarus taxon, Eospirifer the Lazarus-progenitor, and Alispira the new debutante. Eospirifer, the earliest known Spiriferida, possessed a series of evolutionary novelties, such as a well-developed interarea, straight and wide hingeline, fold and sulcus, fine striae on the shell surface, spiralia pointed ventrallaterally, and a pair of jugal processes. ?Eospirifer sp. was recorded from the lOnniella perplexa assemblage of the Glyptograptus persculptus or lower A. acuminatus Zones in Tasmania (LAURIE 1991). The very early Rhuddanian Eospirifer is also known from Tongzi, northern Guizhou, South China. During the later survival (mid Rhuddanian) and the recovery interval (late Rhuddanian-early Aeronian), this genus occupied South China (Eospirifer sinensis RONG et a/.), Qaidam, Tarim, and Kazakhstan (E. cinghizicus BORRISIAK) and Australia. In the late Aeronian, Eospirifer reached many places of Europe, South and North America and may have given rise to many new descendents, that formed a diverse major group of brachiopods in shallow and deeper water regimes in the mid-late Palaeozoic. VI. Borealis Fauna. The late Rhuddanian-early Aeronian may be considered the first recovery interval of brachiopods in the Silurian of South China. This fauna includes abundant atrypoids (Meifodia, Atrypopsis, Athyrisinoides, Beitaia, Nalivkinia, Spirigerina, Zygospiraella, Atrypina, Atrypinopsis), strophomenoids (Leptellina, Aegiria, Katastrophomena, Qianomena, Eostropheodonta), eospiriferids {Eospirifer, Yingwuspirifer, Striispirifer), and pentameroids (Brevilamnulella, Borealis), associated with rare orthoids (Levenea, Dicoelosia), rhynchonelloids (Stegerhynchus), athyridoids (Hindella) and Lingulella. This is emphasized by many newly evolved endemic forms and new immigrants which mark the recovery interval for brachiopods, but the recovery interval of various major groups commenced diachronously. The typical Silurian brachiopods were composed chiefly of Atrypida, Pentamerida, and Spiriferida derived from some sources, such as Baltic, Wales and others, probably refugia in the survivor interval. It should be pointed out that the Atrypida is the first major group of brachiopods to enter a radiation interval in late Rhuddanian, this is, earlier than all others. VII. More than 50 brachiopod genera have been recorded from this interval in Guizhou, Hubei, Sichuan and Hunan. Atrypoids (12 genera: Meifodia, Atrypopsis, Lissatrypa, Hircinisca, Beitaia, Nalivkinia, Spirigerina, Dabashanospira, Gotatrypa, Zygospiraella, Atrypina, Atrypinopsis) and Pentamerida (12 genera: Parastrophina, Chiastodoca, Stricklandiella, Borealis, Pseudoconchidium, Virgianella, Pleurodium, Plicidium, Pentamerus, Apopentamerus, Brevilamnulella, Antirhynchonella) are the two most common major brachiopod groups in this interval. Strophomenida (10 genera: Mirciella, Aegiria, Jonesea, Qianomena, Katastrophomena, Pentlandina, Cyphomenoidea, Eostropheodonta, Palaeoleptostrophia, Spinochonetes) occupies the third position of the brachiopod fauna. The others include Lingulella, Trimerella, Dinobolus, Pseudopholidopsis, Dictyonella, Levenea, 1 Salopina, Stegerhynchus, Virginiata, IFerganella, Nucleospira, Metathyrisina, Whitfieldella, Eospirifer, Striispirifer and Howellella. The mid-late Aeronian is regarded as the first radiation interval for brachiopods in the Silurian of South China. The generic number in this interval can be compared to that of mid Ashgill of South China when the latest radiation took place before the latest Ordovician mass extinction.

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SYSTEMATICS, BIOSTRATIGRAPHY AND PALAEOENVIRONMENTS OF A NEW GENUS OF PHACOPID TRILOBITE FROM THE LATE SILURIAN-EARLY DEVONIAN OF SOUTH EASTERN AUSTRALIA A.C. SANDFORD Earth Sciences, University of Melbourne, Melboune, Vic, Australia Three species of phacopid trilobites, E. hollowayi n. sp, E. sherwini n. sp. and E. wrighti n. sp. are described from the Late Silurian-early Devonian sequence in central Victoria. The incremental increase in the degree of intergenal and pleural spinosity from the stratigraphically lowest to highest species is the most conspicuous character demonstrating the species to be a phylogenetic lineage. The hollowayi-wrighti lineage is closest to spinose phacopid species previously described from New South Wales as Phacops serratus FOERSTE 1888 and Paciphacops (Paciphacops) crawfordae WRIGHT & HAAS 1990, and together define a new genus described herein as Echinops, distinguished from most other phacopid taxa in having occipital and thoracic axial spines. The succession of these and other trilobite species in central Victoria provides an opportunity for re-appraising the stratigraphy of the sequences between Heathcote and Kinglake in which they occur. Most importantly for palaeoenvironmental interpretation, specific horizons in the Mt Ida Formation (such as the placement of the Siluro-Devonian boundary, and the first appearance of E. sherwini) are demonstrated to correlate closely with equivalent horizons in the Humevale Formation, the latter restricted to strata overlying the Clonbinane Member. The spatial and temporal distribution of taphofacies and biofacies for Echinops and trilobite groups indicate deposition of the Ludlow-Lochkovian sequence on a shallow southward and eastward deepening shelf, with brief phases of shallower and deeper conditions, but dominated by a gradual deepening and culminating in the drowning of the shelf and the extinction of the group at the end of the Lochkovian. The sea level changes indicated by the succession of taphofacies and biofacies correspond closely to sea level curves documented for the interval.

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CYCLOCRINITES EICHWALD, 1840 (DASYCLADALES) FROM THE UPPER ORDOVICIAN PORTIXEDDU FORMATION OF SW-SARDINIA AND ITS BEARING ON PALAEOGEOGRAPHY AND SYSTEMATICS. ENRICO SERPAGLI1 and WOLFGANG HAMMANN2 1

Dipartimento di Scienze della Terra (Paleontologia), University di Modena e Reggio Emilia, via University 4,1-41100 Modena, Italy, serpagli@unimo.it Ahornstrasse 3, D-97535 Wasserlosen, Germany

In SW Sardinia a complete, up to 1000 m thick, predominantly siliciclastic Upper Ordovician sequence overlies Cambrian to Tremadocian sediments, and is separated by the Sardic unconformity. The post-Sardic succession starts with largely unfossiliferous conglomeratic, alluvial red beds (Monte Argentu Formation of possibly Soudleyan age), which grades upwards into fossiliferous marine sandstones, siltstones and shales of the Monte Orri-, Portixeddu-, and Domusnovas formations (Longvillan (?) to Rawtheyan) and terminates with the glaciomarine Rio San Marco Formation of Hirnantian age (LEONE et al 1991). The facies development reflects erosion and subsequent marine transgression and submergence of an island which had emerged during the late Early to Middle Ordovician. The Portixeddu Formation consists of sand-, silt- and claystones with intercalated storm layers. The brachiopodbryozoan-echinoderm dominated fauna also yields corals, hyolithids, cornulitids, conularians, gastropods, bivalves, cephalopods, trilobites, ostracods and rare graptolites and conodonts. The lower part of the formation (levels BH2-BH3, Svobodaina havliceki Biozone) correlates largely with the clingani-linearis zones, and the middle to upper part (BH4, Nicolella fauna) probably with the complanatus to basal anceps zones. Cyclocrinites is locally abundant in levels BH2-BH3 but persists into BH4. The patchy distribution within the Portixeddu Formation suggests strong environmental control. As in Sardinia Cyclocrinites always occurs in siltstone beds with more or less frequently intercalated storm layers where it is associated with Svobodaina fauna in BH2-BH3, and with the Nicolella community in BH4, respectively, referable to BOUCOT'S ( 1 9 7 5 ) brachiopod communities B.A. 3-4, a shallow marine environment, probably hardly deeper than 50, m can be inferred. The alga is missing in a nearshore sandstone facies (Calymenella-Dreyfussina association), which suggests that it avoided very shallow and agitated environments. Its absence from claystone levels containing the Nicolella community indicates also strong substrate dependence. These observations fully agree with palaeocological data from Silurian occurrences of Cyclocrinites from the British Isles, North America and Scandinavia (BEADLE & JOHNSON, 1986).

Cyclocrinitid algae, which occur from Middle Ordovician to Early Silurian, are considered reliable indicators of warm circumequatorial shelf seas. They have been described from Laurentia, Baltica, Avalonia, Kazakhstan and South China, and their palaeogeographical distribution hardly exceeds 35° palaeolatitudes. The sudden appearance of Cyclocrinites and of many other faunal elements with Baltic affinities in Sardinia is a strong argument for a close connetion and warming up of the marginal North Gondwana shelf seas during late Caradoc to early Ashgill times. This can best be explained by the arrival of South tropical currents which allowed transport and distribution of warm waters and larvae from Baltica along the North Gonwana margin at about 50°S latitudes. The systematic placement of cyclocrinitids is the subject of a long-lasting debate and attribution to foraminifera, sponges, corals, molluscs and echinoderms has been proposed earlier. During the last two decades the classical interpretation as dasyclad algae by STOLLEY ( 1 8 9 6 ) has been doubted and a close relationship to the probable algal group of receptaculitids was proposed (NLTECKL & TOOMEY 1979). In both groups thallus growth results from growth of old and intercalation of new lateral elements. In Cyclocrinites and other cyclocrinitid genera intercalation occurs in the centre of a star-like assemblage of laterals, the rosette, which is exclusively formed for this purpose and subsequently disappears. As this kind of intercalation has also been observed in the Jurassic dasycladacean genus Goniolina (CHERCHI & SCHROEDER1992), but is totally different in receptaculitids, attribution of cyclocrinitids to dasyclads is suggested.

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REFERENCES

BEADLE, S. C. & JOHNSON, M. E. 1986. Palaeoecology of Silurian cyclocrinitid algae. Palaeontology 29(3): 585-601, 8 text-figs.; London. BOUCOT, A., 1975, Evolution and extinction rate controls, 1-427, Elsevier, Amsterdam. CHERCHI, A. & SCHROEDER, R. 1992. Goniolina hexagona D'Orbigny (Dasycladaceae) aus dem Kimmeridge vom SUdrand der Pommerschen Bucht. Zeitschrift fur geologische Wissenschaften 20(1/2)3: 3-26, 6 pis., 3

text-figs.; Berlin. R., SERPAGLI, E. & VILLAS, E. 1991. Lithostratigraphic units and biostratigraphy of the post-sardic Ordovician sequence in south-west Sardinia. Bollettino della Societa Paleontologica ltaliana 30(2): 201-235,6 pis., 19 text-figs.; Modena.

LEONE, F., HAMMANN, W., LASKE,

NITECKI, M. H. & TOOMEY, D. F. 1979. Nature and classification of receptaculitids. Bulletin du Centre de la

Recherche Exploration-Production Elf Aquitaine 3(2): 725-732; Pau. STOLLEY, E. 1896. Untersuchungen Uber Coelosphaeridium, Cyclocrinus, Mastopora, und verwandte genera des

Silur. Archiv fur Anthropologic und Geologie Schleswig-Holsteins und der benachbarten Gebiete 1(2) : 177282,105 text-figs.; Lipsius & Tischer, Kiel and Leipzig.

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A COMPLETE CATALOGUE OF ORDOVICIAN ACRITARCH SPECIES THOMAS SERVAIS 1 , OLDRICH FATKA2, RAINER BROCKE 3 , KEN J. DORNING 4 , THOMAS HEUSE 5 , ALAIN LE HERISSE6, STEWART MOEYNEUX 7 , CRISTIANA RIBECAI 8 , CLAUDIA V. RUBINSTEIN 9 , MICHEL VANGUESTAINE 10 , MARCO VECOLI11 and REED WICANDER 12 'Pateontologie, UPRESA 8014 CNRS, USTL, SN5, F-59655 Villeneuve d'Ascq cedex, France, Thomas.Servais@u mv-lillel.fr 2 Institute of Geology and Palaeontology, Charles University. Albertov 6. 12843 Praha 2, Czech Republic, fatka@prfdec.natur.cuni.cz 3 Forschungsinstitut Paiaobotanik, Senckenberganlage 25. D-60325 Frankfurt/Main, Germany, rbrocke@sngkw.uni-frankfurt.de 4 Pallab Research, 58 Robertson Road, Sheffield S6 5DX. England and Centre for Palynology, University of Sheffield, Brook Hill, Sheffield S3 7HF, England, k.i.dorning@sheffield.ac.uk Geologisches Eandesamt Thilringen, Weimar, Germany, t.heuse@tlfg-weimar.thueringen.de Pal6ontologie, University de Bretagne Occidentale. Avenue Le Gorgeu. F-29287 Brest cedex, France, alain.le.herisse@univ-brest.fr El Jun, Nanjing Institute of Geology and Palaeontology, Academia Sinica, 39 East Beijing Road, 210008 Nanjing, China, drliiun@ilonline.com 7 British Geological Survey, Keyworth, Nottingham NG12 5GG, UK, sgm@bgs.ac.uk s Dipartimento di Scienze della Terra, Universita di Pisa. Via S. Maria 53 - 56126 Pisa, Italy, ribecai@dst.unipi.it 9 IANIGEA - CRICYT, C. C. 131,5500 - Mendoza. Argentina. rubicaro@supernet.corn.ar 10 Services assoctes de Pateontologie. Sart Tilman. B18. B-4000 Liege. Belgium, M.Vanguestaine@ulg.ac.be u Institut fttr Geologische Wissenschaften, MLU-Halle-Wittenberg. Domstrasse 5. D-06108 Halle (Saale), Germany, vecoli@geologie.uni-halle.de Asa WALLIN, Department of Geology and Geochemistry, University of Stockholm. S-10691 Stockholm, Sweden, asa.wallin@geo.su.se 12 Department of Geology, Central Michigan University. Mount Pleasant. 48859 Michigan, USA, reed.wicander@cmich.edu

Within the IGCP project no 410 "The Great Ordovician Biodiversification Event" different global clade teams have been established to survey and analyse the global biodiversity patterns of individual fossil groups. As for some other fossil groups, acritarch workers decided to compile a complete database on all acritarch taxa described in the Ordovician Series. The compilation of the database is currently in progress. All geographical areas and all Ordovician stages will be covered completely. The files include the following information for each taxon: (1) the species name. (2) its generic attribution, (3) the author, (4) the year of description, (5) the origin (type-locality; type-horizon, type-level), (6) the age, (7) the stratigraphical distribution (if available) This is a contribution to the IGCP project no 410 "The Great Ordovician Biodiversification Event".

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LATE SILURIAN AUTOCHTHONOUS AND ALLOCHTHONOUS CARBONATES IN THE BROKEN RIVER REGION, NORTHEASTERN AUSTRALIA ANDREW SIMPSON Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia, asimpson@els.mq.edu.au The Graveyard Creek Group in north Queensland consists of regionally extensive outcrops of the predominantly turbiditic clastic lithologies of the Quinton Formation (SIMPSON 1995a). In the southern parts of the Broken River region the Quinton Formation is overlain by the Jack Formation. Early Silurian conodont data from allochthonous carbonates within the Quinton Formation has been documented (SLOAN et al. 1995; Simpson 1999). The Jack Formation as presently construed (WLTHNALL & LANG 1992) is lithologically heterogeneous and laterally extensive. Autochthonous carbonates outcrop in two principle areas, in a synclinal structure near the Broken River Crossing and at the Jack Hills Gorge in the vicinity of the type section. In the Jack Hills Gorge the formation consists of two limestone units separated by a clastic interval. The lower limestone has yielded a sparse conodont fauna of broad Wenlock age (SIMPSON 1998a). Above the intervening clastic unit a general Ludlow age is indicated for the distinctive interbedded carbonate and clastic lithologies of the "coral gardens", with the Ludfordian siluricus Zone identified at one level. The rest of the upper limestone unit consists of a thick sequence of massive carbonates, conodont data indicates the entire upper limestone in the type area is Ludlow in age. At the Broken River Crossing there is no equivalent to the lower limestone unit, the "coral gardens" lithology directly overlies clastics of the Quinton Formation. The Gorstian to Ludfordian ploeckensis and siluricus zones are recognised in the "coral gardens" sequence in this area (SIMPSON in press). The uppermost parts of the Jack Formation at the Crossing yield conodonts of the latest Silurian to Early Devonian woschmidti Zone (SIMPSON 1998b), with no obvious break in the sequence. In this region the Jack Formation extends through a generalised Pridoli interval into the Devonian. In all other areas, the Jack Formation carbonates are no younger than Ludlow. In some areas currently construed as Jack Formation and interpreted as lateral equivalents (WITHNALL et al. 1993) conodonts of a mixed Ludlow and Pridoli aspect have been documented (SLOAN et al. 1995). The cannibalisation of limestones of various ages from autochthonous sequences up slope explains this biostratigraphic incompatibility. The unconformity between the Jack Formation and the overlying Shield Creek Formation indicates significant erosion of the pre-Shield Creek units and explains the varying ages at the top of the Jack Formation. The largest carbonate unit in the Quinton Formation outcrops in the headwaters of Turtle and Magpie Creeks near the top of the Quinton Formation. This unit referred to as the Turtle Creek Limestone (MUNSON 1987), the Turtle Creek Member (JELL & TALENT 1989) and the Magpie Creek Limestone (WITHNALL et al 1993) is 5 km long and 300 to 500 m thick. It consists of massive calcilutite, fine calcarenite and discontinuous mudstone. The limestone occurs within turbiditc sequences and is locally brecciated with angular clasts. Munson ( 1 9 8 7 ) interpreted the unit as a large olistolith. WLTHNALL et al. (1993) interpreted the brecciated limestones as stylobreccias and suggested the unit may be in situ. Reconnaissance sampling (SIMPSON, 1995b) yielded a small non diagnostic Silurian conodont fauna. Recent sampling from two new sections through the Magpie Creek Limestone by MUCEP staff and associates has yielded an age diagnostic Late Silurian (Ludfordian) conodont fauna. The fauna consists of the long ranging taxa Ozarkodina excavata excavata, Panderodus unicostatus, Panderodus recurvatus. A number of horizons in both sections have yielded the Ludlow taxa Coryssognathus dubius, Oulodus ?siluricis and Ozarkodina confluens. More critically, both new sections have yielded a small population of Pedavis latialata indicating that some intervals within the Magpie Creek Limestone are the age equivalent of the upper parts of the autochthonous "coral gardens" sequences at both the Jack Hills Gorge and the Broken River Crossing. This, in combination with the sedimentologic and stratigraphic context, suggests that the Magpie Creek Limestone is the allochthonous equivalent of the shelf carbonates of the Jack Formation further to the south. Supporting evidence for this chronological alignment is the recovery of the acanthodian scales Gomphoncus? turnerae from Magpie Creek previously reported from the "coral gardens" unit at the Broken River Crossing (BURROW & SIMPSON 1995).

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REFERENCES C.J. & SIMPSON, A.J. 1995. A new ischnacanthid acanthodian from the Late Silurian (Ludlow, ploeckensis Zone) Jack Formation, north Queensland. Memoirs of the Queensland Museum 3 8 ( 2 ) : 3 8 3 - 3 9 5 .

BURROW,

JELL, J.S. & TALENT, J.A. 1989. Australia: the most instructive sections. In C.H. Holland, & M.G. Bassett (eds.)

A global standardfor the Silurian system. National Museum of Wales, Geological Series No. 9, Cardiff: 183200. MUNSON, T.J., 1987. Silurian stratigraphy and coral faunas from the Graveyard Creek Subprovince, northeast

Queensland. PhD. Thesis, Department of Geology and Mineralogy, University of Queensland, (unpublished). SLOAN, T., TALENT, J.A., MAWSON, R., SIMPSON, A.J., BROCK, G., ENGELBRETSEN, M., JELL, J.S., AUNG, A . K . , PFAFFENRITTER, C., TROTTER, J., & WITHNALL, I.W. 1995. Conodont data from Silurian-Middle Devonian carbonate fans, debris flows, allochthonous blocks and adjacent platform margins: Broken River and Camel Creek areas, north Queensland, Australia. Courier Forschungsinstitut Senckenberg, 182: 1-77. SIMPSON, A. 1995a. Conodont-based ages and stratigraphic relationships of the Siluro-Devonian Graveyard

Creek Group. In G. Brock (ed.), First Australasian Conodont Symposium (AUSCOS1) and the Boucot Symposium, Abstracts and Program, Special Publication of the Macquarie University Centre for Ecostratigraphy and Paleobiology (MUCEP) 1: 71-72. SIMPSON, A. 1995b. Silurian conodont studies in eastern Australia. PhD. Thesis, Department of Earth Sciences,

University of Queensland, (unpublished). SIMPSON, A.

1998a. Lithological sequence and Silurian conodont faunas from the type section of the Jack Formation, north Queensland, Australia. In G. Bagnoli (ed) ECOS VII Abstracts, Bologna-Modena, 1998: 103-104.

SIMPSON, A. 1998b. Apparatus structure of the latest Silurian to Early Devonian conodont Icriodus woschmidti

hesperius Klapper et Murphy, and some comments on phylogeny. In H. Szaniawski (ed), Proceedings of the sixth European conodont conference ECOS VI, Palaeontologica Polonica, 58: 151-167. SIMPSON, A. 1999. Early Silurian conodonts from the Quinton Formation of the Broken River region (North-

Eastern Australia). Abhandlungen Geologischen Bundesanstalts 54: 183-199. SIMPSON, A. (in press) Silurian to basal Devonian conodonts from the Broken River Crossing, north eastern

Australia. Records of the Western Australian Museum. WITHNALL, I . W . , FIELDING, C.R, LANG, S.C. & FLEMING, P.J.G., 1993.; Stratigraphy and sedimentology of the

Silurian to Early Devonian Graveyard Creek Group and Shield Creek Formation, In I.W. Withnall & S.C. Lang (eds), Geology of the Broken River Province, north Queensland. Queensland Geology 4: 55-78. WITHNALL, I.W., & LANG, S.C. 1992. Broken River Special 1:100,000

Industries, Queensland.

scale map. Department of Resource

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RESULTS OF A NEW COMPUTER-BASED METHOD FOR THE DIFFERENTIATION OF CONODONT SPECIES. TERRY SLOAN Faculty of Business, University of Western Sydney, P.O. Box 555, Campbelltown, NSW 2560, Australia This study compared the established method of equal arc segmentation of the outline (KLAPPER AND FOSTER 1986, 1993) with an equal angle segmentation of the conodont outline. Using a plotted points measurement with equal arc segmentation overcame the disadvantages of previous methods of being overly sensitive to qualitative point positioning and in not reflecting growth patterns with point determination.. The method was able to repeat Klapper and Foster's results and proved reliable in determining statistically significant differences between the conodont species studied. Through a comparison of sinistral and dextral elements the data collected was also able to show quantitatively the different symmetry types in conodont element pairs proposed by LANE (1968). The differences observed in sinistral and dextral forms may also point toward handedness in conodonts. The conodonts with statistically significant collections examined in this study included: Amydrotaxis corniculans, Amydrotaxis druceana, Amydrotaxis johnsoni alpha, Amydrotaxis johnsoni beta, Ozarkodina buchanensis, Ozarkodina linearis, Ozarkodina pandora alpha, Ozarkodina prolata, Ozarkodina pseudomiae, Ozarkodina remscheidensis remscheidensis, Ozarkodina remscheidensis repetitor, Pandorinellina exigua exigua, Pandorinellina exigua philipi, Pandorinellina optima, Pandorinellina palethorpei and Pandorinellina steinhornensis miae. REFERENCES KLAPPER, G. AND FOSTER, C.T. JR. 1986. Quantification of Outlines in Frasnian (Upper Devonian) Platform Conodonts. Canadian Journal of Earth Sciences 23(8): 1214-1222. KLAPPER, G. AND FOSTER, C.T. JR. 1993. Shape Analysis of Frasnian Species of the Late Devonian Conodont

Genus Palmatolepis. The Paleontological Society Memoir 32. LANE, H.R. 1968. Symmetry in conodont element-pairs. Journal of Paleontology 42(5): 1258-1263.

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PHYLOGENETIC RELATIONSHIPS OF WENLOCK FENESTRATE BRYOZOA JOANNA F. SNELL Paleobiology Research Group, School of Earth Sciences, The University of Birmingham, Edgbaston, Birmingham. B15 2TT. United Kingdom The Wenlock Series (423 - 428 Ma) in Wales and the Welsh Borderland, United Kingdom, records a time when this area was covered by a relatively warm and shallow shelf sea, with the edge of the continental shelf lying to the west. Fossils from the Much Wenlock Limestone Formation comprise the faunal remnants of small tropical reefs, and a variety of associated reef and inter-reef dwelling organisms, which reflect a shallow-water, carbonate shelf ecosystem. Over 600 species have been recorded, representing almost 30 major taxonomic groups, although the Much Wenlock fauna is typically dominated by the skeletal remains of crinoids, corals, brachiopods, trilobites, algae and bryozoans. By comparison with post-Palaeozoic faunas, the Wenlock Bryozoa remain poorly studied and little-understood. Indeed taxonomic concepts are usually based on insufficient criteria and species descriptions are often lacking, particularly with reference to thin-section work. This is especially apparent in the Wenlock fenestrate Bryozoa, which constitute a major component of the bryozoan fauna from the Much Wenlock Limestone Formation of the U.K. The fenestrates are a distinctive order, characterised by their narrow, unilaminate, erect branches, which bifurcate at regular intervals giving the colony an overall cup-shaped or fan-shaped form. Nevertheless, at species level they exhibit homeomorphy, which has caused a great deal of controversy among researchers. Workers have tended to rely solely on exterior characters, and in recent years have made use of the so-called meshwork formula/micrometric formula (ELIAS & CONDRA 1944, MILLER 1961), which has since been proven unreliable (TAVENER-SMITH 1966). However, the fenestrates, as with all other Bryozoa, possess a large number of exterior and interior characters which make them ideal for phenetic and cladistic means of classification, as has been shown by HAGEMAN ( 1 9 9 1 ) and PACHUT et al (1994). Both of these methods were employed in order to resolve species concepts and interrelationships, as well as providing detailed descriptions of the Wenlock fenestrates from Wales and the Welsh Borderland. Phenetic methods can utilise a variety of numerical tests to analyse quantitative data sets. This statistical approach invariably adopts some means of testing for similarity within the specimens. The multivariate test of cluster analysis was used in this study, since it can be used to classify objects (specimens) into groups (species) by using Euclidean distances. A large number of exterior and interior morphological characters were measured from each specimen, and where possible the type was also included. The means were then entered into a statistical package (Minitab) that performed the analysis. Initial results have been very encouraging, identifying species at a similarity level of greater than 95% with only a few discrepancies, as well as providing some information on the hierarchical classification and relationships within the fenestrates, which can be further tested by cladistics. However, as with all numerical tests, there are a few disadvantages, though it is clear that fenestrate morphospecies can clearly be recognised by this method. The second means of analysis, cladistics, was used to study the genealogical relationships between the species. Cladists tend to only use qualitative characters, but this research also made use of the morphometric characters, by converting them into discrete states. The results have again proved encouraging, with the final cladogram supporting the phenogram. Once again, there are some arbitrary decisions that have to be made when using the computer packages designed for cladistic analysis (i.e. PAUP & MACCLADE). The results from the phenetic and cladistic analyses have clearly demonstrated that these methods can be used to resolve the traditionally problematic taxonomy of the Fenestrata. It is hoped that a similar means of analysis can be used to resolve species concepts and relationships within the other bryozoan orders from the Much Wenlock Limestone Formation of the United Kingdom. REFERENCES CONDRA, G. E., AND ELIAS, M. K. 1944. Study and Revision of Archimedes (Hall). Special Papers of the

Geological Society of America, 53: 243pp. HAGEMAN, S. J. 1991. Approaches to systematic and evolutionary studies of perplexing groups: an example using fenestrate Bryozoa. Journal of Paleontology, 65: 630 - 647.

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MILLER, T. G. 1961. Type specimens of the genus Fenestella from the Lower Carboniferous of Great Britain. Palaeontology, 4: 221 -242. S. 1994. The H. A. Nicholson collection of stenolaemate bryozoans: comparison of cladistic and phenetic classifications. Journal of Paleontology, 68: 978 - 994.

PACHUT, J., ANSTEY, R. L. AND HOROWITZ, A.

TAVENER-SMITH, R. 1966. The micrometric formula and the classification of fenestrate cryptostomes. Palaeontology,

9: 4 1 3 - 4 2 5 .

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SILURIAN ISLANDS IN THE URALIAN SEAWAY CONSTANCE M. SOJA1, BRIAN WHITE2, and A.I. ANTOSHKINA3 1

Department of Geology, Colgate University, Hamilton, NY 13346, USA Department of Geology, Smith College, Northampton, MA 01063, USA 3 Institute of Geology, Komi Science Centre, Uralian Division, Russian Academy of Sciences, 54 Pervomayskaya Street, 167610 Syktyvkar, Russia

The Alexander terrane of southeastern Alaska comprises a stratigraphic record extending with few gaps from the late Proterozoic to the Jurassic. The details of the terrane's geologic history, including the Silurian, before its Mesozoic accretion to western North America are incompletely known and remain controversial. Limestones interbedded with polymictic conglomerates make up much of the Silurian strata in the terrane and record the development and demise of stromatolitic reef complexes. These microbial deposits are of regional and palaeontological significance because they contain palaeogeographically distinctive biotas and yield important insights into Phanerozoic stromatolites that inhabited subtidal environments adjacent to islands in the Uralian Seaway. Ludlow limestones exposed in northern (Willoughby Formation of Glacier Bay) and southern (Heceta Formation of Prince of Wales Island) parts of the terrane formed on shallow shelves that may have bordered volcanic edifices in an island arc. The carbonate platforms were rimmed by skeletal stromatolitic reefs, which wete constructed by calcimicrobes and aphrosalpingid sponges in association with depauperate normal-marine Silurian metazoans. Numerous intra-reefal cavities and fissures are partly to wholly occluded by marine sea-floor cements, including rare dolomite. Intermittent shedding of reefal debris along the foreslope produced megabreccias comprising reefal and lagoonal material that was lithified by coarse rinds of marine carbonate cements. Landward of the barrier reefs, restricted lagoons were inhabited by mollusks and by low-diversity suites of typical Silurian invertebrates, such as brachiopods, corals, crinoids, and trilobites. The depauperate nature of these communities suggests that they were adapted to fluctuations in temperature, salinity, and oxygen concentrations in back-reef lagoons. Similar Ludlovian limestones are known only from the western Urals, the Farewell terrane in southwestern Alaska that yields biotas with Siberian affinities, and possibly Siberia. This suggests that the Alexander terrane had a marine connection to communities evolving along the margins of the Uralian Seaway during the Silurian. Lack of similar biotas so far identified in the Canadian Arctic Islands suggests that migration may have been favored along the northern margins of the seaway rather than to the south (Canadian Arctic), where Caledonide events had a more significant influence on marine habitats. The unusual but highly similar Upper Silurian biotas from southeastern and southwestern Alaska and the Urals imply that the Uralian Seaway was a partially enclosed, narrow, subequatorial seaway affected by fluctuating environmental conditions. Whether environmental restrictions were caused by depressed oxygen levels, elevated temperatures or salinities, or some combination of these factors is not yet known; however, biological migration of some micro- and macroorganisms must have persisted along the northern margins of the seaway for several million years. Limestone deposition in the Alexander terrane was terminated either by widespread collapse of the carbonate platform and /or by an influx of molasse from a southerly direction (present coordinates) during the Late Silurian-Early Devonian Klakas Orogeny. Paleomagnetic data from the molasse indicate a palaeolatitude of 14° N or S during deposition of this clastic wedge. These molasse sandstones (Karheen Formation) contain detrital zircons that were derived from Proterozoic and Upper Archean rocks. Because rocks of these ages do not occur in the Alexander terrane, the terrane must have collided near the end of the Silurian with a cratonic continental margin that provided the detrital zircons. Determining the palaeoposition of the Alexander terrane during the Late Silurian-Early Devonian requires meeting several criteria, including the terrane's involvement in an orogenic event, palaeolatitude of 14°, and an appropriate continental source for the detrital zircons. These requirements are met either by the Scandinavian part of Baltica or eastern Australia. However, the Northern Hemisphere (Laurentia-Baltica-Siberia) option along the Uralian Seaway is favored when the palaeobiogeographic affinities of the biotas are taken into account. Uncertainties about subsequent placement, however, derive from the lack of evidence that the Alexander terrane experienced later deformational episodes (eg., Ellesmerian orogeny) as part of the Caledonide fold belt, absence of Precambrian detrital zircons in Carboniferous and Triassic sandstones in the terrane, and palaeomagnetic data that indicate the Alexander-Wrangellia composite terrane was at 25°-30° N by the Permian somewhere in the palaeo-Pacific. Thus if the Alexander terrane was located along the central portions of the Uralian Seaway 102

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during the Late Silurian-Early Devonian, it was tectonically transported by some unknown means westward along the northern margin of North America and thence southward into the palaeo-Pacific. An alternative Silurian-Early Devonian location of the Alexander terrane near eastern Australia would require environmental limitations similar to those attributed to the Uralian Seaway and considerable post-Silurian tectonic transport to explain the terrene's present location in Alaska. Limestones exhibiting the rather unusual characteristics of those in the Heceta and Willoughby Formations have not been discovered in Australian rocks of the appropriate ages. Thus the Silurian stromatolites under investigation, together with palaeomagnetic data, detrital zircon evidence, and the timing of late-stage Caledonide events, firmly establish genetic and temporal links of the Alexander terrane with other areas along the Uralian Seaway and not with the eastern margin of Gondwana.

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SEQUENCE STRATIGRAPHY, ACRITARCHS AND CORRELATION NEOPROTEROZOIC SEQUENCES BETWEEN CHINA AND AUSTRALIA

THE

LATEST

SUN WEI-GUO 1 , ZANG WEN-LONG 2 and ZHOU CHUAN-MIN 1 1 2

Nanjing Institute of Geology and Palaeontology, Nanjing, P. R. China Geological Survey, Minerals Group, Department of Primary Industry and Resources, SA, Australia

The Xilingian (= upper Sinian) succession in the Yangtze Gorges was deposited in a relatively stable continental shelf environment and contains mainly carbonates with minor fine-grained siliciclastics recording two major transgressions. The depositional environments ranged from outer shelf to nearshore platform regimes. Three prominent third-order sequence boundaries are recognised in the region. The lowest sequence boundary is located between the glacial diamictites of the Nantuo Formation and 'cap dolomite' of the Duoshantuo Formation, which marks a latest Neoproterozoic glacial-eustatic sea level rise. The second boundary at the base of the 'algal stone coal' layer (member 5 of the Doushantuo Formation) is marked by the occurrence of a karstic erosion surface and angular unconformity, suggesting both sea level fall and tectonic activities. The third boundary is located at the base of the Baimatuo Member (Dengying Formation) and is marked by canyon-like structures. The Xilingian sequences are unconformably overlain by the phosphoric carbonates of the Lower Cambrian Tianzhushan Member or Yanjiahe and Shuijingtuo formations in the Yangtze Gorges; the maximum transgression of the Early Cambrian sequence is suggested by the presence of black laminated shale in the middle Shuijingtuo Formation, coincident with or slightly earlier than the appearance of the oldest trilobites in China. The Xilingian sequences contain abundant acritarchs, carbonaceous megafossils and Ediacaran fauna. The lower sequence XI contains megascopic Miaohe Biota and abundant large, morphologically complex, acritarchs. Sequence X2 is marked by the 'algal stone coal' deposits at its base and occurrence of the Ediacaran fauna. Sequence X3 contains skeletal cloudiniids and, in the uppermost part, Early Cambrian small skeletal fossils. Acritarchs, Ediacaran faunas and small skeletal fossils provide a reliable means to correlate Xilingian and Cambrian sequences in China with the Ediacarian Wilpena and Cambrian Hawker Groups in Australia (Fig. 1).

Figure 1. S l r a l i g r a p h b correlation o f I h e l a s t e s l Neoproterozoic sequences b e t w e e n Chliia a n d Australia

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ORGANIC STRUCTURES EUCONODONT ELEMENTS

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PROTOCONODONT,

PARACONODONT

AND

EARLY

HUBERT SZANIAWSKI Institute of Paleobiology, Polish Academy of Sciences, Warsaw, Poland Well preserved, phosphatized organic structures have been noted in many proto-, para-, and euconodont elements from the Upper Cambrian and Lower Ordovician of the Baltic region and in protoconodont elements from the Middle Cambrian of Australia. Untreated, as well as etched, fractured and sectioned specimens were observed in SEM. Especially good preservation of the fine organic structures commonly occur in the material from the Baltic region.

Fig. 1. Schematic longitudinal and cross sections of a protoconodont element (A, B) and a primitive euconodont element (C, D) showing their organic structures. In protoconodonts the outer layer, the fibrilic sheets of the middle layer, and the inner layer (Fig. 1A, B), all originally organic or very rich in organic substance, often remain well preserved even after complete decalcification of the specimen. The thin, compact, outer layer in some specimens is slightly folded, most probably because of post mortal contraction, suggesting its original flexibility. Decalcified specimens usually show lamination of the middle layer but only in some cases is it visible that the lamellae are built of very thin fibrilic sheets. The fibrils are arranged regularly, obliquely to the longitudinal axis of the element. The inner layer is often better preserved than the rest of the element. In some specimens it is visible that the layer is composed of a few thin lamellae. Organic structures of paraconodont elements are generally similar but not so well differentiated. The outer layer does not differ much from that in protoconodont elements. The middle layer has better developed lamination but the fibrils constructing the laminae are not so regularly arranged and rarely well preserved. The inner layer is rather thinner than in protoconodonts and most often apparently composed of a single lamella. Elements of early euconodonts contain a lot of phosphatized organic substance which can be seen after delicate decalcification. The outer coating of the crown, the inner coatings (= coatings of the phosphatic laminae), organic matrix of the phosphatic laminae, and the whole basal body (= basal cone and cone filling) (Fig 1C, D) 105

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can retain their shape even after almost complete dissolution of the coarse phosphate crystals of the conodont crown. The outer coating becomes flexible. The inner coatings in the distal parts of the pecimen are very thin and usually preserved as a filamentous mesh. Toward the base they get thicker and form thin laminae interbedded with the thicker phosphatic laminae. At the base of the crown the phosphatic laminae wedge out and the organic laminae continue as laminae constructing the basal body. The organic matrix of the phosphatic layers is present as filaments ?and thin coatings of apatite crystals. The filaments are arranged along phosphatic layers but also irregularly? (the irregularity could be an artifact caused by processing). They are especially dense near the basal body. Occurrence of apparent organic coatings of the crystals has been observed in two specimens only and is yet to be confirmed. The phosphatization most probably occurred partly in life and partly post mortally. Post mortal phosphatization was certainly very rapid and prevented degradation of the organic substance. In the basal cavities of some specimens of all types Of elements, there occur concentrations of secondary phosphate in the form of granules, coccoids, bacterial pseudomorphs, and also well developed crystals. This suggests that the cavities were originally filled with organic substance. Phosphatization proceeded with the participation of bacteria which which also aided in decomposition. In some cases the cells of bacteria also became phosphatized.

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BIOSTRATIGRAPHICAL

INVESTIGATIONS

PABDEH

FORMATION

KABIRKUH

ANTICLINE, LURESTAN, IRAN MORTEZA TABAEI and S.K. KULSHRESHTHA Mining Engineering Department, Esfahan University of Technology, Esfahan, Iran The present paper deals with the micropalaeontological investigation of Lower Tertiary sediments of Kabir Kuh Anticline, Lurestan, Iran. The Kabir Kuh Anticline is located in the Zagros Belt which lies in the southwest of Iran. The Tertiary sediments in KabirKuh have essentially been laid down under geosynclinal conditions. The faunal assemblage recovered from Lower Tertiary sediments in this area comprises 57 species belonging to 31 genera. This assemblage shows dominance of benthic foraminifera over planktonic foraminifera by having 34 species belonging to 23 genera. The presence of biotic elements reveals Lower Tertiary sediments (Pabdeh Formation) were deposited in comparatively deep marine conditions, probably in the outer shelffupper bathyal zone in the northern part of Gondwana. Based on recovery of both planktonic and benthic foraminiferal assemblages, the Pabdeh Formation has been differentiated into six foraminiferal zones. The marker taxa indicate a Palaeocene-Early Oligocene age for this Formation.

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P ALAEOEN VIRONMENTAL AND PALAEOECOLOGICAL SIGNIFICANCE OF MICROFORAMINIFERAL LININGS IN THE AKLI LIGNITE, BARMER BASIN, RAJASTHAN, INDIA MORTEZA TABAEI 1 and R.Y. SINGH 2 1 2

Mining Engineering Department, Esfahan University of Technology, Esfahan, Iran Center of Advanced Study in Geology, Panjab University, Chandigarh 160014, India

The palynological assemblage of the Akli Lignite in the Barmer District of Rajasthan contains a rich variety of microforaminiferal linings. Altogether, three types of microforaminiferal linings belonging to benthic communities are so far known. Two main types, viz. Trochospiral and Single chambered types, are more frequent in the present assemblage. The usual frequency of these linings approximates that of spores, pollen grains and dinoflagellates, thereby indicating their influx through via waves and currents of the open sea. The present communication deals with the palaeoecological and palaeoenvironmental significance of these microforaminiferal linings in the Paleocene-Eocene sediments of the Barmer Basin, India.

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PALYNOLOGICAL INVESTIGATIONS ON THE LOWER TERTIARY SEDIMENTS OF WESTERN RAJASTHAN, INDIA MORTEZA TABAEI1 and R.Y.SINGH2 1

Mining Engineering Department, Esfahan University of Technology, Esfahan, Iran department of Geology, Panjab University, Chandigarh 160014,India

The present paper deals with the palynological and palaeoenviromental investigations of Tertiary lignite of Western Rajasthan, India. The Western Rajasthan contains a number of sedimentary basins separated from each other by basement ridges. These Tertiary sedimentary basins from north to south are: the Bikaner-Nagaur basin, the Jaisalmer basin, the Barmer basin, and the Sanchor basin. The sedimentation in these basins commenced with the formation of lignite at the base abundant with plant microfossils. This was followed by the precipitation Assilina/Nummulitic limestones and Fuller's earth and finally culminating into the sporadic accumulation of Middle Eocene Discocyclina Limestones in the form of fringing reefs. Altogether 23 rock samples of Carbonaceous Shale and coal were collected from Barsingsar and Hadla in the Bikaner basin and from Akli in the Barmer basin. The palynological assemblages recovered from these localities comprise 169 species belonging to 118 form genera of algae; fungi, pteridophytes, gymnosperms, and angiosperms which 7 form genera and 23 species are identified as new. The assemblages also contain a variety of reworked Permian and Late Mesozoic palynomorphs. Laboratory investigations have revealed that the Lower Tertiary palynological assemblages of western Rajasthan are generally dominated by angiosperms followed by pteridophytes and algae, whereas fungal remains, gymnosperms and foraminiferal linings are present in subordinate quantities. The systematic botanical affinities of different elements in these assemblages and their ecological considerations have demonstrated that the climate during the deposition of these sediments probably varied from SubtropicalTropical (65% families) to Cosmopolitan (23% families) and of Temperate (12% families) zone. The presence of dinoflagellates and foraminiferal linings in the assemblages indicated the accumulation of these Lower Tertiary strata under very low salinity conditions ranging from fresh to brackish water. This is further evident by the occurrence of pollen grains of Nymphaeaceae, Meliaceae, Polygalaceae, and Malvaceae in them. That the depocentre of these sediments was definitely a near shore zone is clear from the fact that the recovered miofloras contained pollen grains of coastal and mangrove plants of families like Palmae, Ctenolophonaceae and Rhizophoraceae.

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PRELIMINARY PALYNOLOGICAL INVESTIGATIONS OF AN ARGILITIC INTERVAL IN THE SOH AREA, NORTHEAST OF ESFAHAN, CENTRAL IRAN MORTEZA TABAEI1 and MEHDI YAZDI2 'Mining Engineering Department, Esfahan University of Technology, Esfahan, Iran department of Geology, Esfahan University, Esfahan, Iran The present paper deals with the preliminary investigation of an Argillaceous horizon in the Soh area, Northeast Esfahan, Central Iran. The Soh area is located in the western part of the Central Iran Zone and represents an outcrop of rocks ranging in age from Silurian to Quaternary. The lower contact of the argillaceous horizon is conformable with dolomitic rocks of Devonian age and is overlain by Upper Permian carbonate sediments. Preliminary palynological investigations reveal that the recovered assemblages from the argillaceous horizon in the Soh area, Central Iran Zone, show an overall dominance of radial monosaccate genera followed by the occurrence of ornamented trilete miospores and acritarchs. The occurrence, in the argillaceous horizon, of marine acritarchs in association with miospores indicates the marine nature of the sediments in this area. The present study also indicates the sedimentary history of this area began in Asselian-Sakmarian time after a hiatus during Carboniferous time and that the first marine incursion took place during Early Permian transgressions in Iran and other Gondwanan countries. On the other hand, the presence of a reworked Givetian fauna in this horizon confirms the gap between the Late Devonian and Early Permian systems. This palaeo-phenomenon can be attributed to Hercynian Epeirogenic movement in the Soh area.

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THE "LOST" EARLY ORDOVICIAN (ARENIG)-DEVONIAN (LATEST GIVETIAN/EARLIEST FRASNIAN) GEORGETOWN CARBONATE PLATFORM JOHN A. TALENT, RUTH MAWSON and ANDREW SIMPSON Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia The "Carriers Well Formation" (WITHNALL& LANG 1993) consists of tracts of turbiditic volcaniclastic arenites and breccias, siltstones, mudstones and cherts with, locally, quartzose arenites and, occasionally, tracts bearing diverse carbonate lithologies ranging from pebbles to olistoliths of kilometric scale (as in Big Stockyard Creek where the largest limestone olistolith is c. 2 km in length). Adjacent tracts of mudstones, quartzose arenites and minor altered basalt and jasper, seemingly without limestone olistoliths, have been referred to as Wairuna Formation (WITHNALL & LANG 1993). None of the "Carriers Well" limestones we have investigated are autochthonous. It has been argued recently (FEIST & TALENT 2000b) that the "Carriers Well" occurrences should be construed as areas of Wairuna Formation charged with carbonate clasts and olistoliths. The Wairuna Formation sensu lato (including the matrix of the "Carriers Well" occurrences) could be largely if not entirely Silurian in age. The age-spectrum represented by the "Carriers Well" carbonate clasts is late Early Ordovician (Arenig) to end-Ordovician with the possibility of earliest Silurian (earliest Llandovery) horizons being involved (FEIST & TALENT 2000b; SIMPSON 2000). Lying to the W/SW of the Wairuna-'Carriers Well" outcrop-tract is the main tract of Crooked Creek Conglomerate, about 1-3 km in width. It consists of generally massive polymictic boulder to cobble conglomerates with, significantly, limestone olistoliths—two of these in the headwaters of the right branch of Crooked Creek (10-11 km NW of Top Hut) being respectively 1700 and 700 m in length and 100-150 m in thickness. The Crooked Creek Conglomerate has been reported to rest unconformably on the Judea Formation, a unit from which poorly preserved mid-Ordovician or younger tabulate corals have been obtained 9.5 km N of Top Hut, though having produced an Early Ordovician (Bendigonian) graptolite, Pendeograptus cf. pendens, from the Diggers Creek area (25 km S of Top Hut) in the type area for the formation. The Crooked Creek Conglomerate has been reported to be around 300 m in thickness (WITHNALL & LANG 1993), tapering to the SE from the vicinity of Top Hut. Greater thicknesses, possibly exceeding 1 km in thickness, may be present in the vicinity of the junction of Dinner and Crooked Creeks, but there is uncertainty due to folding and poor exposures. Conodonts from the limestone olistoliths in the headwaters of the right branch of Crooked Creek are consistent with a Late Ordovician age (PALMIERI in WITHNALL & LANG 1993, p. 56)—in other words, essentially the same age as the bulk of the "Carriers Well" carbonate materials. The Crooked Creek Conglomerate passes upwards gradationally into the Quinton Formation from which conodonts of late Llandovery-earliest Wenlock age have been obtained from a lithologically heterogeneous assemblage of limestone clasts and olistoliths in a channel deposit (SIMPSON 1999). The latter provide a terminus ante quern for the Crooked Creek Conglomerate. Ordovician (Ashgill) limestones occur also as cobbles and small olistoliths in the Perry Creek Formation, notably in Thatch Creek (SLOAN et al 1995) about 35 km ESE of Greenvale, where in addition, there is a component of Llandovery-earliest Wenlock (amorphognathoides Zone) clasts, including one late Llandoveryearliest Wenlock limestone olistolith (on Christmas Creek Station) almost 2 km in length at about the boundary between the Perry Creek and Kangaroo Hills Formations. Our conodont data from Thatch Creek indicate source areas ranging in age from Late Ordovician (Ashgill) to late Llandovery-earliest Wenlock age, with the proportion of Late Ordovician conodonts increasing up-section. This is consistent with erosion cutting gradually deeper into older horizons in the carbonate platform. As with the case of the Wairuna Formation sensu lato (including the matrix of the "Carriers Well" occurrences), the matrix of the Perry Creek Formation could also be largely if not entirely Silurian in age. A similar situation applies to the Kangaroo Hills Formation, gradationally succeeding the Perry Creek Formation (WITHNALL & LANG 1993). Debris flows with carbonate clasts and isolated olistoliths extend the age-spectrum of source limestone bodies to late Prisoli-Pragian and perhaps higher into the Devonian (SLOAN et al. 1995). Included among the source areas would seem to be the limestone members of the Jack Formation of the Broken River area 50 km and more to the SW. The above allochthonous carbonate occurrences are interpreted by us as channel deposits charged with carbonate debris derived from an antecedent carbonate platform on the Georgetown Block west of the Grey Creek Fault Zone and Halls Reward Fault (the NW boundary of the Broken River Province), or, in the case of the large 111

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olistoliths present in the Crooked Creek Conglomerate, "Carriers Well Formation" and Perry Creek and Kangaroo Hills Formations, as having been detached from the margin of this former extensive carbonate platform. We refer to this now "lost" carbonate platform as the Georgetown Carbonate Platform. The saga of this "lost" carbonate platform can be continued through the autochthonous limestone and allochthonous-limestone-bearing units of the Broken River area sensu stricto—from Pandanus Creek in the N to the Broken River and Dosey in the S where carbonate sedimentation continued intermittently through about twothirds of Devonian time—until around the Givetian-Frasnian boundary (MAWSON & TALENT 1989, 1997; WITHNALL & LANG 1993; SLOAN et al 7995; MAWSON et al, 2000; TALENT & MAWSON, 2000; M. FEIST et al. 2000; R. FEIST &TALENT 2000a, 2000b). The record preserved in this area displays long intervals during which carbonate accumulation took place on the Pandanus and Dosey-Craigie Platforms, but seemingly with three significant lacunae: 1. During mid-Lochkovian times when there was extensive cannibalization of previously accumulated (Silurianearliest Lochkovian) carbonate units—expressed in the Ralph Flint Formation). 2. From about mid-Pragian to late Emsian (late inversus Zone)—expressed by the upper arenites of the Shield Creek Formation (not necessarily equating with all of the intervening interval). 3. In the late Givetian (roughly disparilis Zone, equating with part of the upper Papilio Formation)—prior to the onset of Stanley Limestone sedimentation (close to the Givetian-Frasnian boundary). Three significant erosional surfaces have been noted: 1. Between the Jack Formation and the overlying Ralph Flint Formation. 2. Between the Dosey Limestone and the basal Papilio Formation 3. Between the Stanley Limestone and Mytton Formation (MAWSON & TALENT 2000; M. FEIST et al. 2000; FEIST & TALENT 2000a, 2000b).

There are no known outliers of Silurian sedimentary rocks on the Georgetown Block, but there are a few tectonically-preserved occurrences of Devonian sediments (Blue Rock Creek Beds and Conjuboy Formation); these are small and palaeontologically little known (WITHNALL in WITHNALL & LANG 1993, p. 220). In summary, because of their approximate equivalence in time, we interpret the Crooked Creek Conglomerate, Wairuna Formation (specifically its "Carriers Well" component) and the Perry Creek Formation as lateral segments of the same former sedimentary wedge, deepening to the E-cum-NE, its development reflecting events (from late Early Ordovician to early Wenlock) on the adjacent Georgetown Block. The Kangaroo Hills Formation of the Camel Creek region reflects carbonate-sedimentation continuing on the Georgetown block or adjacent to it (perhaps discontinuously) through later Silurian into Devonian times. Carbonate sedimentation (perhaps intermittent) from later Wenlock through to latest Givetian or earliest Frasnian times—when substantial carbonate sedimentation on the Georgetown Block ceased—are more clearly expressed in the autochthonous and associated allochthonous sequences in the Broken River area sensu stricto, SW of the Camel Creek region. Very appealing to us is T.H. Bell's interpretation (quoted by WITHNALL in WITHNALL & LANG 1993, p. 51) of the Judea Formation wrapping around the Gray Creek Anticlinorium (and Gray Creek Fault System) immediately N of Greenvale to become part of the Wairuna Formation. Though based on admittedly tenuous palaeontologic data (WITHNALL in WITHNALL & LANG 1993, p. 51), this would account for the possibility of approximate time-equivalence of the "Carriers Well" materials and the Judea Formation, though, as mentioned above, the matrix of the Wairuna Formation sensu stricto and the matrix of its "Carriers Well" component could be largely if not entirely post-Ordovician. A quest for more compelling data from the rare carbonates in the Donaldsons Well Volcanic Member of the Judea Formation is therefore desirable. REFERENCES FEIST, M., FEIST, R, MAWSON, R. & TALENT, J.A. 2000. First fossil charophytes from Australia: a Sycidiale

from the Frasnian (Late Devonian) Mytton Formation of northeastern Australia. Records of the Western Australian Museum, Supplement 58 (in press). 112

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FEIST, R. & TALENT, J.A. 2000a. Devonian trilobites from the Broken River region of northeastern Australia.

Records of the Western Australian Museum, Supplement 58 (in press). FEIST, R. & TALENT, J.A. 2000b. A new Early Ordovician trilobite from the Broken River region, northeastern

Australia: taxonomy and palaeogeographic implications. Records of the Western Australian Museum, Supplement 58 (in press). MAWSON, R. & TALENT, J.A. 1989. Late Emsian-Givetian conodont stratigraphy and biofacies—carbonate slope

and offshore shoal to lagoon and nearshore carbonate ramp—Broken River, north Queensland, Australia. Courier Forschungsinstut Senckenberg 117: 2 0 5 - 2 5 9 . J.A. 1997. Famennian-Tournaisian conodonts and Devonian-Early Carboniferous transgressions and regressions in north-eastern Australia. Geological Society of America Special Paper 321:

MAWSON, R., & TALENT, 189-233.

MAWSON, R., & TALENT, J.A. 2000. The Devonian of eastern Australia: stratigraphic alignments, stage and series

boundaries, and the transgression-regression pattern re-considered. In: P. Koenigshof & P. Bultynck (eds), Devonian Boundaries and Correlations. Courier Forschungsinstitut Senckenberg (in press). MAWSON, R., TALENT, J.A., MOLLOY, P.D & SIMPSON, A . J .

in prep. The Shield Creek Formation (Early Devonian) of north-eastern Queensland: stratigraphy, conodont data, age and environmental implications.

SIMPSON, A.J. 1999. Early Silurian conodonts from the Quinton Formation of the Broken River region (north-

eastern Australia). Abhandlungen der Geologische Bundesanstalt 54: 181-199. SIMPSON, A.J. 2000. Silurian to basal Devonian conodonts from the Broken River Crossing, north Queensland.

Record of the Western Australian Museum, Supplement 58 (in press). SLOAN, T . R . , TALENT, J.A., MAWSON, R., SIMPSON, A.J., BROCK, G . A . , ENGELBRETSEN, M . J . , JELL, J.S., AUNG,

C., TROTTER, J., & WITHNALL, I.W. 1995. Conodont data from Silurian-Middle Devonian carbonate fans, debris flows, allochthonous blocks and adjacent autochthonous platform margins: Broken River and Camel Creek areas, north Queensland, Australia. Courier Forschungsinstitut Senckenberg

A . K . , PFAFFENRITTER,

182: 1-77. TALENT, J.A., MAWSON, R. & SIMPSON, A.J. 2 0 0 0 . Correlation of the Silurian of Australia. In: E. Landing, and

M.E. Johnson, (eds.), Silurian Terranes and Correlations. New York Sate Museum (in press). WITHNALL, I. W . 1993. Camel Creek Special, 1:250,000 Geological Series. Queensland Department of Minerals

and Energy, Brisbane. WITHNALL,. I . W . & . LANG, S C.

(eds.) 1993. Geology of the Broken River Province, north Queensland.

Queensland Geology 4 : 2 8 9 p.

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SILURIAN TO EARLY CARBONIFEROUS (TOURNAISIAN) PLATFORM-SLOPE SEQUENCES IN EASTERN AUSTRALIA; RECENT ADVANCES IN STRATIGRAPHIC ALIGNMENTS JOHN A. TALENT, RUTH MAWSON and ANDREW J. SIMPSON Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia A survey of the Silurian stratigraphy of Australia, based principally on initiatives in conodont and graptolite biostratigraphy (TALENT et al 2000), embodies new stratigraphic alignments with ramifications regarding the transgression-regression pattern and palaeogeographic models, as well as the timing of tectonic events. Stratigraphic alignments important in a revised palaeogeographic analysis are, arranged generally anticlockwise commencing in the south: 1) The Silurian sequences of eastern Victoria (previously accorded a general Late Silurian age) include almost all intervals from late Llandovery {celloni Zone) through to Pridoli (SIMPSON & TALENT 1995). 2) The Sardine Conglomerate of eastern Victoria is argued to probably reflect earliest Devonian synorogenic sedimentation (MAWSON et al 2000) 3) The classic Yass sequence is now argued to possibly extend down into the late Wenlock (SIMPSON 1995). 4) The Canberra sedimentary sequence is argued to be mainly Ludlow rather than Wenlock (TALENT et al 2000). 5) The Silurian units of the northern Capertee High have been shown recently to extend well down into the Wenlock (COLQUOHOUN 1995). 6) The two major stratigraphic units of the northern Molong Arch, the Nandillyan and Narragal Limestones, have recently been shown to be appreciably different in age (early Wenlock and late Ludlow respectively) (PERCIVAL 1998); other changes in correlations of Silurian rocks from the Molong Arch have come from recent conodont work (TALENT & MAWSON 1999; COCKLE 1999). 7) Silurian rocks are now known from the Tamworth Belt of northern New South Wales, though as yet only from clasts from a half-dozen localities, but implying substantial platform carbonates to the west (TALENT et al 2000) 8) Pridoli-Lochkovian in the Calliope Arc of east-central Queensland has been discounted except for a single locality (Craigilee) (YARROL PROJECT TEAM 1997). 9) Sequences from the Camel Creek Province of northern Queensland, in addition to including late ArenigAshgill olistoliths, include olistoliths producing Llandovery-earliest Wenlock conodonts that testify to cannibalization from platform carbonates of those ages on shelf areas (Georgetown Carbonate Shelf) to the west and/or SW—autochthonous pre-amorphognathoides Zone Llandovery or Ordovician carbonate sequences are not known in the Broken River and Camel Creek provinces (SLOAN et al 1995; SIMPSON 1999, 2000; FEIST & TALENT 2000b). 10) celloni Zone (and some possibly older horizons) through into the Early Devonian in the Hodgkinson Province of northeast Queensland (FORDHAM unpub. data). 11) Improved chronologic control on evaporitic sequences in the Carnarvon (Llandovery to Pridoli) and Canning Basins (only mid-Llandovery and older). Increased precision in stratigraphic alignments, particularly for these areas have resulted in adjustments to the transgression-regression pattern presented previously (NICOLL et al 1994). The new Silurian data, especially from the Indi and upper Buchan rivers of eastern Victoria, are consistent with the main events of the Benambran cycle (arguably the most profound Phanerozoic orogenic cycle in Australia), to have occurred in the interval Ashgill (?late) to early/middle Llandovery, rather than broadly LlandoveryWenlock as previously assumed. 114

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Revised stratigraphic alignments for the Early and Middle Devonian of Australia, resulting principally from an expanded conodont database obtained over the past 5 or 6 years (MAWSON & TALENT 2000), supplemented by data from chitinozoans (WLNCHESTER-SEETO 1993-1997) and with an increasing input from fish micro-remains (eg. DE POMEROY 1995; TURNER 1997) impact, sometimes profoundly, on previous views regarding the transgression-regression pattern. The salient advances listed below, again arranged generally anticlockwise commencing in the south, are primarily from eastern Australian sequences, but attention is drawn to important recent contributions on Late Devonian ammonoid, conodont and spore biostratigraphy in the Canning Basin of north-western Australia (eg. BECKER et at. 1993; KLAPPER et al. 1995; KLAPPER & BECKER 1999; BECKER 2000).

12) The lower part of the Point Hibbs Formation, on the basis of Eognathodus sulcatus, was known to be early Pragian sulcatus Zone, but the kindlei Zone is now identified from the middle of the formation, (WLNCHESTER-

SEETO& CAREY 2000

13) Conodonts from a carbonate fan in the Tyers-Boola area in the Walhalla Synclinorium, 80 km east of Melbourne, have been shown to span an interval from somewhere in the sulcatus Zone, through kindlei Zone to at least early in the early Emsian dehiscens Zone. Limestone clasts from debris flows and isolated limestone megaclasts farther north in the Walhalla Synclinorium testify to cannibalization of a persistent carbonate platform circumferential to a now buried "lost terrain" in south-west Gippsland (MAWSON & TALENT 1994b). The widespread Wilson Creek Shale of the Walhalla Synclinorium has been documented as having co-occurring Monograptus thomasi with Pragian conodonts (CAREY & BOLGER 1995). 14) A widespread pireneae Zone transgression is identified in various sequences in SE Australia: in the BuchanBindi area and at Boulder Flat in eastern Victoria, and in the Taemas-Wee Jasper and seemingly Ravine areas of SE NSW. Limestone clasts from the Wild Horse Formation, the oldest unit in the Wentworth Group of the Mitchell and Wentworth Rivers, eastern Victoria, has produced Polygnathus pireneae suggesting that the base of this unit (and of the Wentworth Group) reflects the same transgression (MAWSON et al. 1992). 15) The Efflux Siltstone and Sawtooth Ridge Limestone, the uppermost units of the Bungonia Group of the Bungonia area (BAUER 1994,1998) are now thought to extend into the Lochkovian, thereby aligning with part of the latest Silurian (Pridoli)—late Lochkovian (pesavis Zone) Windellama Limestone of the Windellama-Jacqua area, SE NSW (MAWSON & TALENT 1999A, 2000). 16) The Cavan Formation, lowest unit of the Murrumbidgee Group of SE NSW, has been documented

(MAWSON et al. 1992) as having conodont faunas indicative of the pireneae Zone passing upwards into earliest

Emsian dehiscens Zone. The overlying units span the interval dehiscens Zone through to serotinus Zone

(MAWSON, MONK, NOVOTNY & TALENT unpub. data).

17) The age of the Cuga Burga Volcanics is now constrained to the eurekaensis Zone and not necessarily all of it, though possibly extending into the earlier part of the delta Zone (TALENT & MAWSON 1999). 18) Conodont data from the Garra Limestone at Eurimbla show that at least the first 17.3 m of section can be confidently assigned to the delta Zone and that there is no positive indication of sulcatus Zone until 793 m above the base of the section (BROCK unpub. data). 19) Conodonts from a substantial tongue of Garra Limestone at Manildra formerly included within the Mandagery Park Formation, have failed to tightly constrain its age but a broad assignment to the delta Zone seems most likely (TROTTER 1991). 20) The platform sequence of the Molong High passes eastwards into a largely turbiditic slope sequence, the Cunningham Formation, draping the western flank of the Hill End Trough. Conodont data from allodapic limestones, isolated limestone megaclasts, carbonate channel deposits, and limestones from debris flows and megabreccias, span the same spectrum of ages (late Lochkovian pesavis Zone to inferred early Emsian dehiscens Zone) documented from the Garra Limestone to the west, but include limestones indicating persistence of carbonate sedimentation on that platform through the perbonus Zone until at least early in the serotinus Zone (TALENT & MAWSON 1999). A late Emsian carbonate fan, the Jesse Limestone at Limekilns, c. 40 km farther east in the Hill End Trough, has proved to be serotinus Zone, though with early dehiscens Zone clasts bearing both Polygnathus dehiscens and P. pireneae low in the succession. These testify to a former, but now "lost", carbonate platform possibly spanning most of Emsian age formerly located somewhere upslope, though in which direction is problematic (TALENT & MAWSON 1999). 115

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21) A considerable volume of age-constraining conodont data is now available for stratigraphic units on the eastern flank of the Capertee High. The Clandulla Limestone has been shown to contain Icriodus woschmidti and I. postwoschmidti faunas, the overlying Yellowman's Creek Formation to embrace the eurekaensis-delta zonal boundary, with the delta-pesavis boundary seemingly occurring low in the overlying, largely siliciclastic Roxburgh Formation. Limestone lenses in the overlying Riversdale Volcanics have produced a sulcatus Zone conodont fauna, whereas the laterally equivalent Kingsford Formation in the vicinity of Ilford has produced a sulcatus/kindlei fauna (COLQUHOUN 1995). In the Mudgee-Mullamuddy Creek area, MCCRACKEN (1990) has identified an early perbonus assemblage from the Warratra Formation (redefined) in the Queens Pinch area, as well as identifying pireneae Zone conodonts from limestone clasts in the upper part of the formation. Also documented are numerous perbonus Zone to serotinus Zone faunas from the overlying Sutchers Creek Formation. A similar age-span of conodonts has been obtained from the ?Sutchers Creek Formation at Flirtation Hill on the southern outskirts of Mudgee, with the perbonus Zone being represented. These conodont faunas have been obtained from limestone clasts (TALENT & MAWSON 1999). Limestones on the western limb of the Mount Knowles Anticline, west of Mount Frome, have produced another perbonus Zone conodont fauna (COLQUHOUN 1995). 22) Devonian sedimentary units make up a large proportion of the c. 450 km Tamworth Belt tract of primarily Palaeozoic rocks, also referred to as the Gamilaroi Terrane. Most zones from late Lochkovian (pesavis Zone) to Givetian (varcus Zone) are represented. The conodont data are derived from a broad spectrum of platform carbonate environments as well as from allochthonous carbonates in debris-flow deposits (MAWSON et al 1996 and in prep.). The Glencairn Limestone (LEITCH et al ms.) of the Willow Tree Creek area 20 km north of Tamworth has produced Pedavis pesavis and Kimognathus alexeii indicative of the pesavis Zone (latest Lochkovian); Pragian horizons may occur higher in the sequence. The latter interval is represented in the ?a!lochthonous limestone megaclasts in the valley of Limestone Creek in the Pigna Barney area, c. 100 km south-east of Tamworth where DONGOL (1995) has documented conodonts indicative of the sulcatus-kindlei interval. The Bennys Tops Limestone of the Pigna Barney area, has produced conodonts indicative of the dehiscens Zone (DONGOL 1995). This is interesting as the dehiscens Zone is widely represented in the Tamworth-Nundle area, but in exclusively allochthonous facies (FUREY-GREIG 1995). 23) The Sulcor Limestone outcropping extensively in several outcrop-tracts in the Sulcor-Yarramanbully areas north and northeast of Attunga (MAWSON & TALENT ms.) is at least in part late Emsian serotinus Zone. It passes upwards into fine arenites and minor autochthonous limestones, and these in turn into typical Moore Creek Limestone, the base of which approximates the costatus-australis boundary (MAWSON & TALENT 1994a; MAWSON & TALENT ms.). Sedimentary units bearing limestone clasts derived from the Sulcor Limestone or its temporal equivalents are widespread in the Silver Gully Formation or its approximate equivalents in the Nundle area. The base of the Silver Gully Formation is very late in the Emsian, serotinus Zone or, conceivably, early in the patulus Zone (MAWSON & TALENT unpub. data). The transition from Moore Creek Limestone to Yarrimie Formation is Early varcus Zone (MAWSON & TALENT 1994a). The Yarrimie Formation extends through the late Givetian, to the hermanni and into the Frasnian (MAWSON et al 1997 and unpub. data). 24) The Mount Holly Beds of the Rockhampton-Raglan region of central coastal Queensland, is now construed as consisting of two units: an older Mount Holly Beds sensu stricto of late Emsian age, overlain, apparently unconformably, by a newly proposed unit, the Mount Alma Formation (YARROL PROJECT TEAM 1997) including, near its base, large allochthonous bodies of late Emsian limestones patulus Zone limestones

(MAWSON et al 1995).

25) Limestones in the Mount Warner Volcanics of the Mount Morgan/Dee Range area, have produced conodonts indicative of the australis and kockelianus Zones providing a tie to the Mount Morgan sequence (TAUBE et al in prep.). 26) Carbonate intervals in units circumferential to the Precambrian Anakie Inlier have been demonstrated to be of various ages from earliest Emsian (dehiscens Zone) to Eifelian australis or kockelianus Zone or slightly younger (MAWSON & TALENT 2000). 27) The Wilkie Gray Group of the Burdekin Basin is late Emsian, serotinus Zone and possibly inversus Zone (MAWSON & TALENT 1997). It is separated by an erosional surface from the Fanning River Group representing a transgression commencing after a hiatus of 6 conodont zones. Polygnathid conodonts from the Cultivation Gully Formation, the youngest unit of the Fanning River Group, imply a deepening event of broadly late Givetian age (TALENT & MAWSON 1994; MAWSON & TALENT 1997). 116

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28) The "upper limestone" of the Jack Formation of the Broken River area has been demonstrated to extend from the Pridoli into early Lochkovian, specifically in the vicinity of the Broken River Crossing/Bullock Creek area (SIMPSON 1999, 2000). An important erosional interval with significant topography developed on the "upper limestone" of the Jack Formation occurred during mid-Lochkovian times (SLOAN et al 1995; MAWSON, TALENT & SIMPSON, in prep.). The overlying Ralph Flint Formation has been demonstrated to produce zonally mixed Ludlow-Pridoli-early Lochkovian conodont faunas (SLOAN et al 1995; MAWSON, TALENT, MOLLOY & SIMPSON in prep.). 29) The Ralph Flint Formation passes upwards gradually into the Shield Creek Formation, a unit with three substantial limestone members straddling the Lochkovian-Pragian boundary (pesavis-sulcatus zones). The Shield Creek Formation sedimentation appears to reflect a c. 4 0 0 Ma deformation event (WITHNALL & LANG 1993). 30) The Broken River Group (late Emsian-latest Givetian) is construed as extending through three palaeogeographic units: two carbonate platforms (Pandanus and Dosey-Craigie platforms) with an intervening submarine valley (Burges Submarine Valley) containing turbiditic sequences. (MAWSON & TALENT 1989; WITHNALL & LANG 1993; SLOAN et al 1995). Significant erosional surfaces occur between the Dosey Limestone and the basal Papilio Formation, and between the Stanley Limestone and Mytton FORMATION (MAWSON & TALENT 2000; FEIST et al. 2000; FEIST & TALENT 2000a). Some salient results from the Late Devonian and Tournaisian are as follows: 31) Conodonts indicate that Yarrimie Formation sedimentation in the Tamworth Belt of NE NSW extended into the late Frasnian, and that the Baldwin Formation is broadly Famennian in age (MAWSON et al 1997; MAWSON & TALENT unpub. data). Allochthonous limestone blocks in the predominantly volcanic/volcaniclastic Mostyn Vale Formation to the W, range from possibly triangularis Zone (Ijamieae Zone) to the rhenana and linguiformis Zones (WRIGHT et al 1990; WLNCHESTER-SEETO & PARIS 1995), equating with part of the Yarrimie-Baldwin succession. 32) Limestone occurrences in the watersheds of Trotter and Hamilton Creeks south of Mount Morgan have produced Frasnian conodonts but are inferred to be allochthonous and therefore of little value for tying radiometric and biostratigraphic time-scales (MAWSON & TALENT 2000). 33) A transgressive event of some scope is indicated by the presence of early Famennian conodonts low in the Greybank Volcanics north-east of Clermont (MAWSON & TALENT 2000). 34) In the Burdekin Basin, major transgressions, coinciding with global transgressive events, have been discriminated during the Early marginifera and expansa zones, with a third having its inception close to the Famennian-Tournaisian boundary (MAWSON & TALENT 1997). 35) Conodonts (FORDHAM, unpub. data) from largely, if not entirely, allochthonous carbonates in the flyschoid Hodgkinson Formation of the Hodgkinson Province indicate ages of the source rocks (and minimal age for the formation) as extending through Devonian time into the Early Carboniferous. 36) A Devonian-Carboniferous boundary sequence NW of Twelve Mile Bore in the Canning Basin, trenched in quest of conodont and ostracod data, has demonstrated that the latest Devonian praesulcata and earliest Carboniferous sulcata Zones, and accordingly the Devonian-Carboniferous boundary, can be discriminated in Australia on the basis of siphonodellid conodont data (TALENT, ENGELBRETSEN, MAWSON, MCCRACKEN & JONES ms.).

37) Conodont data from the Hardwick, Ruxton and Teddy Mountain Formations, of the Burdekin Basin, Clarke River Basin and the Broken River area respectively, demonstrate major transgressions at about the base of the sulcata Zone and in the sandbergi and Early crenulata Zones (MAWSON & TALENT 1997, 1999b). [This is a contribution to IGCP Project 421: North Gondwana mid-Palaeozoic bioevent/biogeography patterns in relation to crustal dynamics.] REFERENCES BAUER, J. 1994. Siluro-Devonian Bungonia Group, Southern Highlands, NSW. Helictite 32(2):25-34.

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BAUER, J. 1998. Geology of the Bungonia Group, p. 3-19. In J. Bauer & P. Bauer (eds.), Under Bungonia. JB Books, Oak Flats, New South Wales. BECKER, R.T. 2000. Palaeogeographic relationships and diversity of Upper Devonian ammonoids from Western

Australia. Records of the Western Australian Museum, Supplement 58 (in press). BECKER, R.T., HOUSE, M.R. & KLRCHGASSER, W.T. 1993. Devonian goniatite biostratigraphy and timing of

facies movements in the Frasnian of the Canning Basin, Western Australia. In: E.A. Hailwood & R.B. Kidd, (eds.), High resolution stratigraphy. Geological Society of London Special Publications. 70: 293-321. CAREY, S . P . & BOLGER, P.F. 1995. Conodonts of disparate ages from the Wilson Creek Shale (Lower Devonian,

Victoria, Australia); stratigraphic implications. Alchering, 19: 73-86. COCKLE, P. 1999. Conodont data in relation to time, space and environmental relationships in the Silurian (late

Llandovery-Ludlow) succession at Boree Creek (New South Wales, Australia). Abhandlungen der Geologische Bundesanstalt (Wien). 54: 107-133. COLQUHOUN, G.P.

1995. Early Devonian conodont faunas from the Capertee High, NE Lachlan Fold Belt, southeastern Australia. Courier Forschungsinstitut Senckenberg 182: 347-369.

DE POMEROY, A. 1995.

Australian Devonian fish biostratigraphy in relation to conodont zonation. Courier Forschungsinstitut Senckenberg, 182: 4 7 5 - 4 8 6 .

DONGOL, G.M.S. 1995. Age-diagnostic Early Devonian (Pragian and early Emsian) conodonts and other fauna

from the eastern end of the Tamworth Terrane, NSW. Memoirs of the Association of Australasian Palaeontologists 18: 131-142. FEIST, M., FEIST, R., MAWSON, R. & TALENT, J.A. 2 0 0 0 . First fossil charophytes from Australia: a Sycidiale

from the Frasnian (Late Devonian) Mytton Formation of northeastern Australia. Records of the Western Australian Museum, Supplement 58 (in press). FEIST, R. & TALENT, J.A. 2000a. Devonian trilobites from the Broken River region of northeastern Australia.

Records of the Western Australian Museum, Supplement 58 (in press). FEIST, R. & TALENT, J.A. 2000b. A new Early Ordovician trilobite from the Broken River region, northeastern

Australia: taxonomy and palaeogeographic implications. Records of the Western Australian Museum, Supplement 58 (in press). T.M. 1995. The "Nemingha" and "Loomberah" limestones (Early Devonian; Emsian) of the Nemingha-Nundle area, northern New South Wales: conodont data and inferred environments. Courier Forschungsinstut Senckenberg 182: 2 1 7 - 2 3 3 .

FUREY-GRIEG,

KLAPPER, G . & BECKER, R.T.,1999. Comparison of Frasnian (Upper Devonian) conodont zonation. Bolletino

della Societa Paleontologia Italiana, 37: 339-348. KLAPPER, G., KIRCHGASSER, W.T. & BAESMANN, J.F. 1995. Graphic correlation of a Frasnian (Upper Devonian)

composite standard. In K.O. Mann & H.R. Lane (eds.), Graphic correlation. Society of Sedimentary Geology (SEPM), Special Publication 53: 177-184. MCCRACKEN, S. 1990. Stratigraphy, chronology and regional significance of Devonian allochthonous blocks

and debris flows in the vicinity of Queens Pinch, near Mudgee, NSW. BSc Honours Thesis; School of Earth Sciences, Macquarie University, Sydney. 1995. Early Devonian polygnathid lineages with special reference to Australia. Courier Forschungsinstut Senckenberg 182: 389-398.

MAWSON, R.

MAWSON, R., PANG, D., & TALENT, J.A. 1997. G.J. Hinde's (1899) Devonian radiolarians from the Tamworth

area, north-eastern New South Wales: stratigraphic and chronologic context Proceedings of the Royal Society of Victoria 109: 233-256.

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MAWSON, R. & TALENT, J.A. 1989. Late Emsian-Givetian conodont stratigraphy and biofacies—carbonate slope

and offshore shoal to lagoon and nearshore carbonate ramp—Broken River, north Queensland, Australia. Courier Forschungsinstut Senckenberg 117: 205-259. MAWSON, R. & TALENT, J.A., 1994a. The Tamworth Group at Attunga, New South Wales: conodont data and

inferred ages. Courier Forschungsinstitut Senckenberg 168: 37-59; Frankfurt., 1994a) MAWSON, R., & TALENT, J.A. 1994b. Age of Early Devonian submarine fan deposits and isolated megaclasts,

east-central Victoria. Proceedings of the Royal Society of Victoria 106: 31-70. Famennian-Tournaisian conodonts and Devonian-Early Carboniferous transgressions and regressions in north-eastern Australia. Geological Society of America Special Paper 321:

MAWSON, R., & TALENT, J.A. 1997. 189-233.

MAWSON, R. & TALENT, J.A., 1999a. Silicified Early Devonian (Lochkovian) brachiopods from Windellama,

southeastern Australia. Senckenbergiana lethaea 79: 145-190. 1999b. Early Carboniferous (mid-Tournaisian) conodonts from northeastern Australia. Bolletino della Societa Paleontologia Italiana, 37: 407-425.

MAWSON, R . & TALENT, J.A.

MAWSON, R., & TALENT, J.A. 2000 in press. The Devonian of eastern Australia: stratigraphic alignments, stage

and series boundaries, and the transgression-regression pattern re-considered. In: P. Koenigshof & P. Bultynck (eds.), Devonian Boundaries and Correlations. Courier Forschungsinstitut Senckenberg. (ms): Devonian limestones from the Sulcor and Yarramanbully areas of northeastern New South Wales: conodont data and implications.

MAWSON, R. & TALENT, J.A.

G.A. & ENGELBRETSEN, M . J . 1992. Conodont data in relation to sequences about the Pragian-Emsian boundary (Early Devonian) in southeastern Australia. Proceedings of the Royal Society of Victoria 104: 2 3 - 5 6 .

MAWSON, R. & TALENT, J.A., BROCK,

MAWSON, R., TALENT, J.A. & FUREY-GREIG, T . M . 1995. Coincident conodont faunas (late Emsian) from the

Yarrol and Tamworth belts of northern New South Wales and central Queensland. Courier Forschungsinstitut Senckenberg 182: 4 2 1 - 4 4 5 . MAWSON, R., TALENT, J.A. & LEITCH, E.C.,1996. Ages and relationships of Devonian rocks from the southern

New England fold belt. Abstracts of the Geological Society ofAustralia 41: 277. MAWSON, R., TALENT, J.A., MOLLOY, P.D & SIMPSON, A.J.

in prep.: The Shield Creek Formation (Early Devonian) of north-eastern Queensland: stratigraphy, conodont data, age and environmental implications.

NICOLL, R. S., ROMINE, K. K. & WATSON, S.T. 1994. Early Silurian (Llandovery) conodonts from the Barbwire

Terrace, Canning Basin, Western Australia. AGSO Journal of Australian Geology and Geophysics 15: 247255. PERCIVAL, I.G. 1998. The age of the Nandillyyan and Narragal Limestones, Molong High, central western New

South Wales. Geological Survey of New South Wales, Quarterly Notes 107: 12-19. SIMPSON, A.J. 1995. Silurian conodont biostratigraphy in Australia: a review and critique. Courier Forschungsinstitut Senckenberg 182:325-345. SIMPSON, A.J. 1999. Early Silurian conodonts from the Quinton Formation of the Broken River region (north-

eastern Australia). Abhandlungen der Geologische Bundesanstalt 54: 181 -199. SIMPSON, A.J. 2000. Silurian to basal Devonian conodonts from the Broken River Crossing, north Queensland.

Record of the Western Australian Museum, Supplement 58 (in press). SIMPSON, A.J., & TALENT, J.A. 1995. Silurian conodonts from the headwaters of the Indi (upper Murray) and

Buchan rivers, southeastern Australia, and their implications. Courier Forschungsinstitut Senckenberg 182: 79-215.

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SLOAN, T.R., TALENT, J.A., MAWSON, R., SIMPSON, A.J., BROCK, G . A . , ENGELBRETSEN, M . J . , JELL, J.S., AUNG,

A.K., PFAFFENRITTER, C., TROTTER, J., & WITHNALL, I.W. 1995. Conodont data from Silurian-Middle Devonian carbonate fans, debris flows, allochthonous blocks and adjacent autochthonous platform margins: Broken River and Camel Creek areas, north Queensland, Australia. Courier Forschungsinstitut Senckenberg 182: 1-77. TALENT, J. A. & MAWSON, R. 1994. Conodonts in relation to age and environmental framework of the Burdekin

Basin (Mid-Devonian), north-eastern Australia. Courier Forschunginstitut Senckenberg 168: 61-81. TALENT, J.A. & MAWSON, R. 1999. North-eastern Molong Platform and adjacent Hill End Trough, New South

Wales: mid-Palaeozoic conodont data, age-inferences, and implications regarding platform exposure and carbonate sedimentation offshore. Abhandlungen der Geologische Bundesanstalt (Wien). 54: 49-105. TALENT, J. A., MAWSON, R. & SIMPSON, A.J. 2000 in press. Correlation of the Silurian of Australia. In: Landing,

E. & Johnson, M.E. (eds), Silurian Terranes and Correlations. New York Sate Museum. TAUBE, A., FORDHAM, B . G . , MAWSON, R. & TALENT, J.A. (ms.): Repetition of the Mount Morgan stratigraphy

and mineralization in the Dee Range, central Queensland: implications for exploration. TROTTER, J. A. 1991. New data on the conodont, brachiopod and coral faunas from Manildra, N.S.W. MSc

dissertation (unpublished), 105 p.; School of Earth Sciences, Macquarie University, Sydney. TURNER, S. 1997. Sequence of Devonian thelodont scale assemblages in East Gondwana. Geological Society of

America Special Paper, 321: 2 9 5 - 3 1 5 . R., MAWSON. R., TALENT, J.A., AND COOPER, B.J. 1995. Late Pragian conodonts from an environmentally hostile context, the Lilydale Limestone of central Victoria. Courier Forschungsinstitut Senckenberg 182: 3 7 1 - 3 8 7 .

WALL,

1993. Chitinozoan assemblages from the Pragian (Lower Devonian) of eastern Australia. Proceedings of the Royal Society of Victoria 105: 8 5 - 1 1 2 .

WINCHESTER-SEETO, T .

T. 1993. Chitinozoa from the Early Devonian (Lochkovian-Pragian) Garra Limestone, central New South Wales, Australia. Journal of Paleontology 67: 738-758.

WINCHESTER-SEETO,

T. 1996. Emsian Chitinozoa from the Buchan area of southeastern Australia. Acta Palaeontologica Polonica 41: 149-230.

WINCHESTER-SEETO,

T. 1997. A preliminary survey of the biogeography of Early Devonian Chitinozoa. Geological Society of America Special Paper, 321: 235-244.

WINCHESTER-SEETO,

WINCHESTER-SEETO, T & CAREY, S.P. 2000. Chitinozoans and associated conodonts from the Lower Devonian

Point Hibbs Formation, Tasmania, Australia. Records of the Western Australian Museum, Supplement 58 (in press). WINCHESTER-SEETO, T. & PARIS, F. 1995. Late Givetian and Frasnian chitinozoans from Australia, France and

Pakistan in relation to conodont zonation. Courier Forschungsinstitut Senckenberg 182: 451-473. WITHNALL, I . W . & . LANG, S.C. Queensland Geology 4 : 2 8 9 p.

(eds), 1993. Geology of the Broken River Province, north Queensland.

WRIGHT, A . J , PICKETT, J.W, SEWELL, D , ROBERTS, J. & JENKINS, T . B . H . 1990. Corals and conodonts from the

Late Devonian Mostyn Vale Formation, Keepit, New South Wales. Memoirs of the Association of Australasian Palaeontologists 10: 2 1 1 - 2 5 4 . YARROL PROJECT TEAM 1997. New insights into the geology of the northern New England Orogen in the

Rockhampton-Monto region, central coastal Queensland: Progress report on the Yarrol project Queensland Government Mining Journal, May 1997: 1 1 - 2 6 .

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CONODONTS, THELODONTS AND PHOEBODONTS - TOGETHER AT LAST KATE M. TRINAJSTIC Department of Geology and Geophysics, University of Western Australia, Perth,WA 6009, Australia During their intensive investigations of the Palaeozoic of Western Australia Drs Klapper and Nicholl collected and dissolved for conodonts many samples from the Upper Devonian of the Canning Basin. Besides conodonts, which allowed the age of the samples to be precisely determined, numerous chondrichthyan and thelodont micro-fossils were found. Samples from the Middle Frasnian division of the Horse Springs section are particularly rich in phoebodont teeth, chondrichthyan denticles and thelodont scales. The nearby Virgin Hills and Gogo Formations were also rich in micro-vertebrate remians. The discovery of conodonts with microvertebrates in the Canning Basin has enabled, more precise dating of the ichthyoliths from the Gneudna Formation in the Carnarvon Basin from which only rare, and long ranging conodonts have been recovered. The Upper Devonian sedimentary sequence of the Canning Basin bears a rich micro-vertebrate assemblage which enables biostratigraphic correlation with the Carnarvon Basin and the Shishtu Formation in eastern Iran and offers the potential for correlation with the Montagne Noire, France and faunas from central USA.

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CONODONT BIOSTRATIGRAPHY IN TWO WELLS OF THE BEAVERHILL LAKE GROUP, UPPER MIDDLE TO LOWER UPPER DEVONIAN, CENTRAL ALBERTA, CANADA T.T. UYENO and J.C. WENDTE Geological Survey of Canada, 3303-33 Street N.W., Calgary, Alberta T2L 2A7, Canada rd

An integrated study of conodont biostratigraphy with transgressive-regressive sequence stratigraphy has related genetic successions of the Beaverhill Lake Group over a widespread area of central Alberta. The study area spans from the eastern shelf, through an intervening basin, to the western shelf. This paper reports on the conodont biostratigraphy of basinal successions (Waterways Formation) from two wells, 50 kms apart, near the western shelf, within a sequence-stratigraphic framework. In the area of the two wells in central Alberta the Waterways Formation consists of up to approximately 150 m of interstratified basinal limestones and calcareous shales. The entire Waterways succession is divided into nine genetic units which have been correlated throughout the basin. These genetic successions are assignable to six conodont zones: in ascending order, the Upper subterminus Fauna (approximately equivalent to the Upper disparilis Subzone), the norrisi Zone, and Montagne Noire (MN) zones 1 to 4. This suggests that there was continuous sedimentation through the Givetian-Frasnian (Middle-Late Devonian) boundary. Palmatolepis transitans makes a late entry within MN Zone 4. The base of MN 4 was determined by the first occurrence of a new species of Ancyrodella, that has been demonstrated to be restricted to that zone through graphic correlation (KLAPPER, pers. comm., 2000). The correlations made independently from physical sequence stratigraphy and conodont biostratigraphy corroborate each other.

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LOCHRIEA CRUCIFORMIS ZONE (LOWER CARBONIFEROUS) AND ITS CORRELATION WITH FORAMINIFER AND CORAL SUBDIVISIONS (NORTH OF URALS, IZYAYU SECTION) Y.A. VEVEL1, A.V. ZHURAVLEV2,O.L. KOSSOVAYA2, and D.B.SOBOLEV3 'All-Russian Oil Prospecting Institute AII-Russian Geological Research Institute Geological Institute of Komi SC RAS 2

The lower boundary of the Lochriea cruciformis Zone is one level discussed as a possible Lower Serpukhovian boundary. Another boundary level is the base of the Neoarchaediscus parvus - Pseudoendothyra globosa foraminifer Zone. One of the reasons for disagreement with the position of the boundary, based on conodonts and foraminifers, is the method of zone determination: conodont zones are based on first appearance of the index-species, but foraminifer zones are traditionally index-species acme - zones. Nowadays, investigation of the Visean/Serpukhovian boundary is carried out both in the stratotype region (Zaborie Quarry) and in the Urals. In the Polar and South Urals this boundary was approximately dated by the base of the Lochriea cruciformis Zone it is correlated, using foraminifers, with the Neoarchaediscus parvus Zone. The same zone is considered in the proposed stratotype of the Serpukhovian Stage (Zaborie Quarry). Detailed faunal characteristics of the transitional Visean/Serpukhovian interval were obtained from the Izyayu section (North of the Urals), representing rather deep-water facies. The Lochriea cruciformis conodont zone is determined by the first appearance of L. cruciformis in the phylogenetic succession L. senckenbergica - L. cruciformis in this section. Besides the Urals, the same succession has been observed in the Cantabrian Mountains. The base of the L. cruciformis Zone considered here as one of the possible levels of the lower Serpukhovian boundary coincides with a decrease in foraminiferal diversity. In comparison with the base of the L. cruciformis Zone, Neoarchaediscus parvus appears substantially below in association with Lonsdaleia. This assemblage is considered as the Upper Visean. Based on foraminifers, the Lower Namurian boundary can be proved by the phylogenetic transition from Howchinia to Monotaxinoides. LALOUX (1988) had first proposed this phylogenetic succession and it is shown by data from the Izyayu section. Rugose corals occurring a little below Monotaxonoides transitorius and represented by Kizilia, Lonsdaleia, and Siphonodendron junceum suggest an Upper Visean age. Thus, there are no coincident phyletic changes in conodont and foraminiferal lineages considered as possible criteria for the Visean/Serpukhovian (Namurian) boundary.

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THE TREMADOC (ORDOVICIAN) GRAPTOLITE DIVERSIFICATION EVENTS WANG XIAOFENG Yichang Institute of Geology and Mineral Resources, Yichang, Hubei, China Restudy of Tremadoc graptolites and their sequences from several sections of shelf margin and slope to basinal facies on the North and South China plates and from around the world reveals that five graptolite diversification events can be recognized in the interval between the first appearance of earliest planktic graptodendroids and the base of the Tetragraptus approximatus Zone. Bioevent 1 is marked by the first appearance of pendent and horizontal quadriradiate planktic nematophorous graptolites, represented by Rhabdinopora! taojiangensis (JIN & WANG 1977) with rare dissepments, and Staurogratus dichotomus form-species. Study of Rhabdinopora? praeparabola specimens, collected from Dayangcha , Hunjiang, Jilin, China the Naersnes road section, Norway, and from Green Point and Broom Point South sections, Newfoundland by ERDTMANN (1982, 1988), further indicates that the formal Dictyonema taojiangensis JLN & WANG has nomenclatorial priority over Rhabdinopora! praeparabola. The FAD of these planktic graptolites has revealed the earliest Ordovician graptolite phylogenetic event from rooted dendroids to planktic nematophorous graptodendroids in association with the earliest Ordovician transgression. R.l taojiangensis usually occurs earlier than R. parabola, though it could range up to the base of the R. parabola Zone. The following graptolite bioevent 2, equivalent to Assemblage 1 (COOPER & LLNDHOLM 1990), is marked by the FAD of the pendent, quadriradiate Rhabdinopora parabola with horizontal, quadriradiate, slender nondissepiment-bearing staurograptids (S. hyperboreus). The former possesses two dicalycal autothecae, given off from thl2 , forming the quadriradiate proximal end and the latter is different from the associated S. dichotomus form-species (Erdtmann 1988) in possessing very slender stipes, long branching distance and no dissepiment. The first appearance of pendent and horizontal triradiate rhabdinoporids (/?. flabelliformis and anisograptids) indicates bioevent 3. This graptolite plexus probably corresponds to Assemblage 2 (COOPER & LlNDHOLM 1990) or Assemblages 2a and 2b (ERDTMANN 1988). A new, well-preserved, graptolite plexus found from the Paijiazhun section, Jiuxi, Taoyuan, Hunnan, has revealed the presence of the pendent triradiate Rhabdinopora, referred to as R. hunanensis n.sp. Associated graptolites include the horizontal triradiate "Radiograptus" rosieranus, Anisograptus matanensis etc. Redescription of R. flabelliformis, based upon type specimens reposited at Lund University, shows it to possess a triradiate, rather than a quadriradiate proximal development, as described by WANG et al. (1998). The subsequent bioevent 4 is defined by the incoming of the earliest reclined and horizontal biradiate anisograptids (Psigraptus with isolated, slender thecae apertures, "Clonograptus") reported from deep shelf to slope facies in Dayangcha section, Hunjiang, Jilin (WANG & CHEN 1997) and Qinhuangdao, Hebei (SONG 1993). In shallow shelf facies, a probably equivalent graptolite fauna, represented by pendent biradiate rhabdinoporoids (emended Bryograptus, B.l Rhabdinopora and the anglica), along with the triradiate R. hunannensis n.sp., occurs just above the exclusively triradiate, pendent horizontal Anisograptus in the Panjiazhu section, Taoyuan. The first appearance of biradiate, declined anisograptids (A. delograptus, Kiaerograptus) marks bioevent 5, which was reported from several sections in the North and South China plates and is equivalent to Assemblage 3 (COOPER & LlNDHOLM 1990). Bioevent 6, equivalent to Assemblage 4 (COOPER & LlNDHOLM 1990), is indicated by the appearance of a diverse transitional graptolite fauna characterized by the polyphyletic loss of bithecae (Hunnegraptus, Clonograptus s.s., Paradelograptus, Araneograptus), from anisograptid to dichograptid. The Late Tremadoc graptolite fauna has not been found yet in China due to a depositional hiatus or facies change caused by the global Ceratopyge eustatic event. REFERENCE COOPER, R.A. LINDHOLM, K. 1990. A precise worldwide correlation of early Ordovician graptolite sequence.

Geological Magazine, 127(6): 497-525. B.-D., A re-organization and proposed phylogenetic classification of planktic Tremadoc(early Ordovician) dendroid graptolites. Norsk Geologisk Tidsskrift., 2: 121-145.

ERDTMANN,

ERDTMANN, B.-D. 1988, The earliest Ordovician nematophorid graptolites: taxonomy and correlation Geological

Magazine, 125(4): 327-348. JIN YUQIN & WANG XIAOFENG, 1977, The discovery of graptolites in the Baishuxi Formation of the Early

Ordovician in central Hunan and the multiramous graptolites in the Qiaotingzi Formation. Professional Paper of Stratigraphy and Palaeontology, 3: 74-85. Geol. Pub. House, Beijing ( in Chinese) 124

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1993. The Xinchangian (Early Ordovician) graptolite sequence in Qinhuangdao area, Hebei. Stratigraphy and Palaeontology of China, 2:199-214.

SONG LISHENG.

WANG HAI-FENG, COOPER, R.A. & ERDTMANN, B . - D , 1998. Restudy on the earliest Ordovician graptolites from

the Dayangcha section in Jilin. Acta Palaeonologica Sinica, 37(2): 2 1 3 - 2 3 4 . WANG XIAOFENG & CHEN XIAOHONG. 1997. Astogeny, evolution and classification of Psigraptus—a critical

review. In Wang Hongzhen & Wang Xunlian (eds.) Centennial Memorial Volume of Prof Sun Yunzhu: Palaeontology & Stratigraphy, 9 8 - 1 0 3 . China Univ. of Geosci. Press.

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PALAEO-GEOMORPHOLOGICAL SIGNIFICANCE OF MIOCENE AND PLIOCENE EURYHALINE OSTRACODA IN THE NEPEAN 1 BOREHOLE, PORT PHILLIP BASIN, SE AUSTRALIA M.T. WARNE School of Ecology and Environment, Deakin University, 662 Blackburn Road, Clayton, Victoria, 3168, Australia The occurrences of ostracod faunas which include the extant euryhaline taxon Osticythere baragwanathi (CHAPMAN & CRESPIN) in latest Miocene and Pliocene sediments of the Nepean 1 borehole, Port Phillip Basin, mark a local palaeo-geomorphological change from the open, normal shallow marine coastlines of the Oligocene to earliest Upper Miocene, to restricted marine barrier coastlines (with coastal lagoons of fluctuating salinity) dating from the latest Upper Miocene to Holocene. Osticythere baragwanathi is common in coastal barrier lagoon and some estuarine environments of the modern southeast Australian coastline. This species is adapted to environments in which there are large fluctuations in salinity. It is also known to tolerate significant fluctuations in dissolved oxygen content within modern marginal marine waters (YASSINI & WRIGHT 1 9 8 8 ; YASSINI & JONES 1 9 9 5 ) . The earliest appearance of Osticythere baragwanathi so far known is in the Nepean 1 borehole at 178.3 metres (WARNE 1 9 9 3 ) . Specimens from this latest Upper Miocene interval are associated with a diverse, shallow-marine ostracod fauna and with polished vertebrate fragments. The latter association enables an approximate lithostratigraphical correlation with the Phosphatic Nodule Bed at the base of the Black Rock Sandstone outcropping in cliffs at Beaumaris along the coast of Port Phillip Bay. At the Beaumaris locality, the Phosphatic Nodule Bed overlies an erosion surface (unconformity). The large shark teeth and other vertebrate remains within the Phosphatic Nodule Bed are probably lags associated with the unconformity surface and sea-level fall. However the finer -grained sediments associated with these types of bioclasts within the 'phosphatic nodule bed' interval of the Nepean 1 borehole, contain well preserved planktonic and autochthonous benthonic calcareous microfossil faunas. Although reworked calcareous microfossils are also apparent within these sediments, the well-preserved autochthonous benthonic microfossil component suggests subsequent flooding of the continental shelf. This flooding culminated in the formation of a thin sedimentary (sand and silt) veneer across the shelf and partly incorporated clasts from the previously formed lag. The presence of ostracod specimens reworked from older strata and a relatively 'concentrated' abundance of well-preserved microfossils as well as the polished appearance of many microfossils, suggests a relatively low sedimentation rate for the 'phosphatic nodule bed' interval within the Nepean 1 borehole. From a sequence stratigraphic perspective, the fossil occurrences within the 'phosphatic nodule bed' interval of the Nepean 1 borehole suggest the presence of a coincident sequence boundary and condensed section, the latter marking a latest Upper Miocene flooding of local shelf regions. By analogy with modern day ostracod faunas, the presence of rare O. baragwanathi in association with a generally diverse and autochthonous population of normal shallow marine ostracod species within the 'phosphatic nodule bed' interval of the Nepean 1 borehole, suggests that the depositional environment was a sheltered, but open, shallow oceanic embayment or near an inlet channel along the seaward coast of barrier islands. This ostracod occurrence, therefore, arguably marks the genesis of Port Phillip Bay as a coastal geomorphological feature. The 'phosphatic nodule bed' ostracod fauna within the Nepean 1 borehole includes a conspicuous number of new shallow marine species not present in older Oligocene to Miocene strata and marks the base of a significant evolutionary and migration event within shallow marine palaeoenvironments of the Bass Strait region. For instance, within some normal shallow marine taxonomic clades of SE Australia (ie Neobuntonia Hartmann), member species are conspicuous in latest Lower to earliest Middle Miocene faunas, poorly represented in latest Middle and earliest Upper Miocene faunas, again becoming conspicuous (with newly evolved representative species) in some latest Upper Miocene and younger faunas. The ostracod fauna present within the 'phosphatic nodule bed' horizon of the Nepean 1 borehole is dissimilar to the ostracod faunas from the outcropping ferruginised cliff beds of the Black Rock Sandstone resting above the Phosphatic Nodule Bed at Beaumaris - the later upper Black Rock Sandstone beds having far less taxonomic and taphonomic diversities and abundances. The Black Rock Sandstone units above the Phosphatic Nodule Bed at Beaumaris appear to be shallow shelf to shoreface deposits and ostracod specimens from these units are generally opaque and do not have a polished appearance. The sedimentation rate for these upper beds of the 126

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Black Rock Sandstone was high relative to that for the 'phosphatic nodule bed' interval within the Nepean 1 borehole. These upper beds of the Black Rock Sandstone are succeeded by backshore/barrier deposits generally lacking in calcareous marine fossils (Red Bluff Sands) and the overall sequence above the nodule bed at Beaumaris appears to be a prograding (in part, shoaling upwards) succession. The diversity of ostracod preservation states within the 'phosphatic nodule bed' ostracod fauna of the Nepean 1 borehole indicates that the fauna is an agglomeration of fossils derived from a complex of sources. Most specimens contemporaneous with deposition are translucent or pyritised and unfragmented, whereas reworked specimens may be opaque or pyritised and have a frosted appearance with abraded ornamental features or are fragmented with extensive rounding of fracture edges. Within the contemporaneous portion of the ostracod assemblage, most species are represented by adult and juvenile specimens, suggesting that this portion of the assemblage is mostly a biocoenosis. Rare ostracod specimens have a ferruginous coating. This may be a deep red colour (similar to the ferruginisation colour of the phosphatic nodules at Beaumaris) or a light yellow brown colour. Some specimens with a deep red ferruginous coating show clear indications of abrasion suggesting that they have been reworked from older strata; however other specimens with a deep red ferruginous coating are well preserved. Specimens with a lighter coloured ferruginous coating are generally well preserved but are perhaps transported specimens - possibly derived from nearby penecontemporaneous marine sediments that had been subjected to a synchronous ferruginising subaerial environment. The light yellow brown ferruginous coating of these specimens is similar to that occurring on ostracod specimens within beds of the Black Rock Sandstone overlying the Phosphatic Nodule Bed at Beaumaris. The latter also show a uniformity in preservation state, except for the occasional reworked glauconised specimens. The rare specimens of Osticythere baragwanathi within the 'phosphatic nodule bed' interval of the Nepean 1 borehole are not ferruginised and show good preservation of fine ornamental features. The second observed occurrence of O. baragwanathi within the Nepean 1 borehole is at 149.0 metres. At this earliest Upper Pliocene interval ninety-eight percent of specimens belong to this ostracod species. Other ostracods present include the euryhaline species Leptocythere hartmanni (MCKENZIE), Xestoleberis cedunaensis HARTMANN and Tanella gracilis KLNGMA, indicating a restricted coastal lagoon (or perhaps salt wedge estuarine) environment. This low diversity, high abundance fauna is succeeded by a very high diversity, high abundance fauna at 145.1 metres within the Nepean 1 borehole. The latter, which includes in situ , but subordinate abundances of O. baragwanathi, L. hartmanni and X. cedunaensis specimens amongst a diverse, shallow normal marine ostracod fauna, probably indicates a lagoonal environment with large ocean exchanges and close to normal marine salinities. However, given the limited lateral extent of these deposits within the Port Phillip Basin, they may also have formed in a former river valley into which earliest Upper Pliocene seas flooded (CARTER 1985). These Upper Pliocene assemblages are made up of adult and juvenile specimens that are well preserved (often pristine) and unferruginised. These assemblages also contain species such as Mutilus pumila (BRADY), which are not present within latest Upper Miocene strata of the Port Phillip Basin, but are present within Lower Pliocene strata of the Gippsland Basin, where they make their first appearance (WARNE 1992, 1993). The intervals within the Nepean 1 borehole that yield Upper Pliocene lagoonal assemblages are succeeded by partly ferruginised Pliocene shoreface, foreshore and backshore strata and Pleistocene dune deposits poor in Ostracoda. Whilst transitional continental - marine facies of the Upper Oligocene - Middle Miocene occur extensively within the Gippsland Basin (ie. Balook Formation) and elsewhere, these are not yet known to be associated with euryhaline Ostracoda such as O. baragwanathi. Consequently, the latest Upper Miocene occurrences of O. baragwanathi documented here, currently provide the earliest local evidence for barrier coastlines typical of present day SE Australia. REFERENCES CARTER, A.N. 1985. A model for depositional sequences in the Late Tertiary of southeastern Australia. Special

Publication of the South Australian Department of Mines and Energy, 5: 13-27. M.T. 1992. Late Tertiary ostracod biostratigraphy of the Sorrento Graben, Victoria, Australia. Geological Society of Australia Abstract, 32: 182-183.

WARNE,

M.T. 1993. Micropalaeontological evaluation of eustatic and tectonic influences on Late Tertiary marine sedimentation within the Port Phillip at Western Port Basins, Victoria, Australia. In K.G. McKenzie & P.J. Jones (eds.) Ostracoda in the Earth and Life Sciences; Proceedings of the Eleventh International

WARNE,

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Symposium on Ostracoda, Warrnambool, Victoria, Australia 1991 A.A. Balkema, Rotterdam, Netherlands; 259 - 275. YASSINI, I. & JONES, B.G. 1995. Foraminiferida and Ostracoda from estuarine and shelf environments on the

southeastern coast of Australia. The University of Wollongong Press, Wollongong, Australia; 1-484. YASSINI, I & WRIGHT, A.J. 1988. Distribution and ecology of Recent ostracodes (Crustacea) from Port Hacking,

New South Wales. Proceedings of the Linnean Society of New South Wales, 110 (2): 159-174.

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IN SEARCH OF TRIGGERING BIODIVERSIFICATION EVENT

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MECHANISMS

FOR

THE

GREAT

ORDOVICIAN

B.D. WEBBY Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW, 2109, Australia, bwebbv@Jaurel.ocs.mq.edu.au The most rapid and long-sustained evolutionary radiations of marine animal life occurred during Ordovician time. It resulted in a three-fold increase in biodiversity - to more than 4,300 genera - from levels attained in the Early Cambrian explosion (SEPKOSKI 1995), and saw the emergence of the last few "modern" phyla, not confirmed previously by abundant occurrences (eg., bryozoans and vertebrates). But it produced many other biotal changes. Among benthic organisms, more complete utilization of ecospace above and below the sea floor, adaptation to a wider range of onshore to offshore habitats, and development of more highly differentiated provincial faunas, as well as significant increases in the occupancy of the pelagic realm. Diversity of marine calcareous "algae" also more than doubled - of the eleven groups known from the Ordovician, six of them were new. Climatic conditions were predominantly greenhouse with an oceanic circulation of sluggish, warm, saline, oxygen-depleted water masses and reduced latitude and vertical temperature gradients, but oceanic overturn to cold, oxygenated bottom waters, enhanced upwelling and increased thermal gradients apparently accompanied by the establishment of the intensive, short-lived, 0.5 to 1.0 Ma, late Ashgillian (Hirnantian) glaciation. Of the extinction pulses, only the glacially-induced, end-Ordovician mass extinction had major global impact. Early Ordovician biodiversity records are depicted by SEPKOSKI (1995) as being similar to those of the Late Cambrian, with about 500 genera recorded at any one time, part of his so-called "quiescent interval" between the Early Cambrian "explosion" and the Ordovician radiations, though still characterized by high turnover (comparatively high rates of extinctions and appearances). Diversification of biotas in the Early Ordovician seems to have been limited by a combination of factors: (1) high levels of atmospheric C02(some 14-17 times modern levels); (2) higher-than-normal global temperatures (21 to 22°C, compared to present day 15°C); (3) elevated sea-level highstands (100-150 m above present day levels), that caused episodic flooding of platforms including spread of poorly ventilated anoxic waters from the oxygen minimum zone; (4) innumerable short-term (metre-scale) peritidal and subtidal cycles of platform successions causing habitat instability; and (5) conditions were unfavourable for aerobic respiration of metazoans in tropical surface waters until the end of the Early Ordovician when oxygen levels had increased to 45%PAL (present atmospheric level) (WLLDE 1987). The high temperatures stimulated calcification processes in cyanobacterial floras (RIDING 1992), but they caused stenothermal organisms (metazoans) to be replaced or displaced because of their more limited tolerances (KAUFFMAN & FAGERSTROM 1993). Pulchilaminid stromatoporoids (calcified sponges) were the first large, near metre-size, domical-shaped, skeletal "reef'-building metazoans to appear towards the end of the Early Ordovician. The first diversity increase commenced about the beginning of the Middle Ordovician, and reached a peak in the early Darriwilian with about 950 genera (and localized diversity "highs" for the articulate brachiopods, cephalopods and graptolites). Then a limited diversity decline occurred in the late Darriwilian to about 900 genera (SEPKOSKI 1995). In Laurentia the Early-Middle Ordovician boundary marks an important turnover of faunas (eg., appearances of new Ordovician trilobite groups), and change from trilobite-dominated to brachiopod- and ostracode-dominated shell-beds (DROSER & SHEEHAN 1997). Lower sea-level highstands characterize the Laurentian platform record, with flooding restricted to outer shelf areas. Indicators of very warm waters (calcified cyanobacteria) only rarely occur. Factors that may have helped to facilitate the biodiversity increase include: (1) progressive increase to higher levels of oxygenation of surface waters (from 45 to 80%PAL), (2) warm, but not higher-than-normal, temperatures, (3) lower sea-level highstands, and (4) more limited spread of anoxic waters onto platform areas. In the Late Ordovician, there were more significant, second and third, diversity maxima. The second rise commenced in the latest Darriwilian, and continued undiminished to a mid-Caradocian peak of about 1,600 genera, with almost all the main groups sharing in the increase (SEPKOSKI 1995). Two important "habitat" biodiversification events also characterize this interval: (1) the great expansion of metazoan-dominated reefs across the Middle-Late Ordovician transition, that included a number of groups (eg., bryozoans, corals and stromatoporoids) developing significant roles as reef-builders ; and (2) a major increase in bioturbation, resulting achieving deeper and more intensive utilization of infaunal ecospace (DROSER & BOTTJER 1989). Its timing remains uncertain, either correlating with the reef event, or comprising a separate, later Caradocian development. The substrate must have become adequately oxygenated to allow this deeper burrowing. WILDE et al. (1991) 129

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presented 0 2 values for the Late Ordovician of 65-80%PAL. Some platforms were again drowned by elevated sea level highstands, but the high temperatures of the Early Ordovician were not repeated - only one reef complex in equatorial N China still exhibits calcified cyanobacteria. In contrast, stratigraphic evidence of glacial activity in N Africa suggests this part of the Gondwanan land mass had drifted over the S pole. This may have triggered an increase in global latitudinal gradients, and established the cooler subpolar currents that were deflected northwards towards continental masses of equatorial Laurentia, temperate Baltica, and margins of Gondwana (WILDE 1991). The tropical Laurentian platform developed two separately differentiated carbonate associations - warmer, shallow (Photozoan-type) stromatoporoid-dominated assemblages and, with spread of the cooler subpolar currents, cooler (Heterozoan-type) bryozoan-dominated assemblages that either occupied deeper parts of the platform, or shallower positions during cooler phases. In Baltica, cool, shallow, temperate (Heterozoan-type) assemblages predominate, but when the Baltic plate drifted into low palaeolatitudes during the mid-Caradocian, warm, shallow (Photozoan-type) stromatoporoid assemblages also appeared. Differentiation of these separate warm and cool carbonate assemblages on different platforms must have further enhanced levels of biodiversity increase through this interval. A short-lived diversity decrease of 1,500 genera followed in the latest Caradocian-earliest Ashgillian, then a third peak during the middle Ashgillian to the greatest level of diversification, near 1,800 genera (SEPKOSKI 1995). The widest global spread of warm-water reefs occurred at this time, as well as, the development of high latitude, cool-water mounds in Spain and bryozoan-dominated biostromes in N Africa, only 2,000 km from the S pole. Articulate brachiopods, echinoderms, corals, gastropods, bivalves, cephalopods and graptolites all exhibit peaks of diversification, immediately prior to the dramatic, glacially-induced, late Ashgillian extinction. Only about 750 genera were left in this second most intensive mass extinction event of Phanerozoic time, with disappearances of about 60% of genera and 26% of families. The abstract is a contribution of IGCP 410 (The Great Ordovician Biodiversification Event). REFERENCES DROSER, M.L. & BOTTJER, D.J.,1989. Ordovician increase in extent and depth of bioturbation: Implications for understanding early Paleozoic ecospace ultilization. Geology, 17: 850-852.

DROSER, M.L. & SHEEHAN, P.M. 1997. Palaeoecology of the Ordovician radiation: resolution of large-scale patterns with individual clade histories, palaeogeography and environments. Geobios, 20: 221-229. KAUFFMAN, E.G. & FAGERSTROM, J.A. 1993. The Phanerozoic evolution of reef diversity, 315-329. In R.E.

Ricklefs and D. Schluter, (eds.). Species diversity in ecological communities: historial and geographical perspectives. University of Chicago Press, Chicago. RIDING, R. 1992. Temporal variation in calcification in marine cyanobacteria. Journal of the Geological Society

of London, 149: 979-989. 1995. The Ordovician radiations: diversification and extinction shown by global-level taxonomic data. In J.D. Cooper, M.L. Droser and S.C. Finney, (eds.), Ordovician Odyssey: Short Papers, 7th International Symposium, Ordovician System: Fullerton, Pacific Section Society for Sedimentary Geology, 77: 393-396.

SEPKOSKI, J.J. JR.

WILDE, P. 1987. Model of progressive ventilation of the Late Precambrian-Early Paleozoic Ocean: American

Journal of Science, 287: 442-459. WILDE, P. 1991. Oceanography in the Ordovician. In C.R. Barnes and S.H. Williams, (eds.), Advances in Ordovician geology. Geological Survey of Canada, Paper 90-9: 283-298. WILDE, P., BERRY, W.B.N. & QUINBY-HUNT, M.S. 1991. Silurian oceanic and atmospheric circulation and chemistry. Special Papers in Palaeontology, 44: 123-143.

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EARLY AND MIDDLE ORDOVICIAN CHITINOZOANS FROM THE CANNING BASIN, WESTERN AUSTRALIA; A REAPPRAISAL OF THE WORK OF COMBAZ & PENIGUEL (1972) AND THE BIOSTRATIGRAPHIC IMPLICATIONS. THERESA WINCHESTER-SEETO Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia, twinches@laurel.ocs.mq.edu.au COMBAZ & PENIGUEL ( 1 9 7 2 ) completed the first study of chitinozoans from the Canning Basin, based on seven

wells drilled in the quest for oil from the across the northern part of the basin. Their work included Early and Middle Ordovician chitinozoans from the Nambeet, Thangoo (=Willara) and Goldwyer formations. Using a combination of both chitinozoans and acritarchs, they were able to establish five local "zones"; this work constituted some of the most important biostratigraphic work in the Canning Basin at that time. The present investigation reexamines chitinozoans extracted from samples of two of these cores, namely Willara #1 and Goldwyer #1, from the original collections of Combaz & Peniguel. A reassessment of the taxonomic placement of the chitinozoan species has been undertaken, with the advantage of a scanning electron microscope observation and additional taxonomic and biostratigraphic information gathered over the past 28 years. The samples from Willara #1 and Goldwyer #1 yielded nineteen species. Four of the zones identified by Combaz & Peniguel are represented in the two cores. Two of these species were also found in the mid-late Arenig strata of the Nora and Coolibah formations of the Georgina Basin in Queensland (PLAYFORD & MILLER 1988). Several species also occur in contemporaneous sediments from Canada and Spitsbergen, namely: Conochitina langei COMBAZ & PENIGUEL, Lagenochitina combazi FINGER, Conochitina subcylindrica COMBAZ & PENIGUEL, Calpichitina windjana WLNCHESTER-SEETO, FOSTER & O'LEARY, and possibly Lageonchitina esthonica EISENACK. Previous studies of the upper Goldwyer and Nita formations by WINCHESTER-SEETO et al. ( 2 0 0 0 , in press) also identified Conochitina poumoti COMBAZ & PENIGUEL, Conochitina kyros BOCKELLE, and a species of Belonechitina that were also found in Laurentia. ACHAB (1989) established a biozonation of the Ordovician in Canada, and three of the six zones from the Early

Ordovician to the end of the Darriwilian can be identified in the Canning Basin. These include the zones: Lagenochitina esthonica/Conochitina raymondi, Conochitina langei/Conochitina brevis and Conochitina turgida/Conochitina subcylindrica. ALBANI et al. (1999) suggested a possible additional zone in an unnamed segment immediately above the Cyathochitina jenkinsi zone, that yielded a new species of Belonchitina; this new species is also found in the upper Goldwyer and Nita formations. No specimens of the index species Cyathochitina jenkinsi NEVILLE or Lagenochitina pirum (ACHAB) were found in the present study. Cyathochitina hunderumensis GRAHN, PARIS & NOLVAK has now been found in the Canning Basin, as well as Sweden and Britain. This species may act as a link between the Laurentian biozonation, that can be applied in a modified form in the Canning Basin, and the one developed for Baltica. Apart from the seemingly ubiquitous Belonechitina micracantha (EISENACK), no species were found definitely in common with North Gondwana. This study confirms the strong link between Laurentia and Australia in the Early and Middle Ordovician, possibly related to the low latitude position of both continents during this time interval. REFERENCES 1989. Ordovician chitinozoan zonation of Quebec and western Newfoundland. Journal of Paleontology, 63, 14-24

ACHAB, A.

ALBANI, R., BAGNOLI, G. & STOUGE, S. 1998. Chitinozoan assemblages dynamics during tectonic instability -

Cape Cormorant Formation (Llanvirn), western Newfoundland. CIMP Symposium and Workshops, 35. Pisa. COMBAZ, A. & PENIGUEL, G. 1972. Etude Palynostratigraphique de l'Ordovicien dans quelques sondages du

Basin de Canning (Australie Occidentale). Bulletin du Centre de Recherches de Pau - SNPA, 6, 121-167. G. & MILLER, M.A. 1988. Chitinozoa from Lower Ordovician strata of the Georgina Basin, Queensland (Australia). Geobios, 21: 17-39

PLAYFORD,

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WINCHESTER-SEETO, T . , FOSTER, C. & O'LEARY, T .

2000 (in press). Chitinozoans from the Middle Ordovician (Darriwilian) Goldwyer and Nita formations, Canning Basin (Western Australia). Acta Palaeontologica Polonica

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NAMURIAN (CARBONIFEROUS) CONODONTS, HOLOTHURIAN FORAMINIFERS FROM THE SHOTORI RANGE, EASTERN IRAN

SCLERITES

AND

MEHDI YAZDI1 and GLENN A. BROCK2 1

Department of Geology, Faculty of Sciences, University of Esfahan, Esfahan 81744, Islamic Republic of Iran Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia

A fossiliferous horizon in the Sardar Formation, some 810 metres above the base of stratigraphic section at Howz-e-Dorah, in the Tabas area, eastern Iran has yielded a diverse fauna including foraminifera, conodonts, holothurian sclerites, sponges and microvertebrates. Recovered Late Namurian conodont species such as Locheria commutata, Rhachistognathus muricatus, Diclinognathodus noduliferous noduliferous, and ldiognathodus sinuatus indicate the horizon can be accurately dated as Late bilineatus Zone in the Namurian. Significantly, a high percentage of the fossil assemblages has also been recovered from the base of the crinoidal bed in the other areas in the Shotori Range and in the Shirgesht area to the north, suggesting the horizon may be a useful marker horizon. The fossil assemblages can be compared to at least one of the calcarous concentration reported by Sandberg & Gutschick (1984), from the Woodman Formation and equivalents in Utah and adjacent regions in USA. The holothurian sclerites Achistrum micholsoni, Eocaudina gutschicki, Eocaudina scotica and Protocaudina cf. kansasensis are closely comparable to forms described from Scotland and the USA (FRIZZELL & EXLINE 1955). Recovered agglutinated foraminifers from this horizon include Tolypommina spp. and Hyperammina sappingtonensis (GUTSCHICH 1962). The close similarity of these fauna supports previous reconstructions indicating a close connection between Iran and Euramerica during the Namurian. REFERENCES FRIZZEL, D. & EXLINE, H. (1955) Monograph of fossil holothurian sclerites. Bulletin of the Missouri University.

School of Mines and Metallurgy. Technical Serie,s 89: 1-204. GUTSCHICK, R . C . ( 1 9 6 2 ) Arenaceous foraminifera from oncolites in the Mississippian Sappington Formation of

Montana, Journal of Paleontology 36 (6): 1291 -1304. C.A. & GUTSCHICK, R . C . ( 1 9 8 4 ) . Distribution, microfauna and source rock potential of Mississippian Delta Phosphatic Member of Wooden Formation and equivalents, Utah and adjacent states. In J. Woodward, F.F. Meissner, and J.L. Clayton, (eds.). Hydrocarbon source rocks of the greater Rocky Mountains region, Rocky Mountains, 135-178. Association of American Geologist.

SANDBERG,

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EARLY ORDOVICIAN ACRITARCHS IN THE WARBURTON BASIN, SOUTH AUSTRALIA WEN-LONG ZANG Geological Survey, Minerals Group, Department of Primary Industry and Resources, SA, Australia The Cambro-Ordovician Warburton Basin underlies the late Palaeozoic to Mesozoic Cooper and Eromanga Basins that comprise the largest onshore oil and gas province in Australia. The extent of the basin is defined by drilling and seismic interpretation and is normally divided into eastern and western sub-basins. The investigation of the basin received little attention until commercial petroleum flows were obtained from the Warburton Basin rocks. The stratigraphy of the Warburton Basin is well studied. It contains four sedimentary sequences and more than eight trilobite and three conodont zones have been recognized (SUN 1996), which provide a valuable basis for acritarch biostratigraphy and correlation. Acritarchs were sampled from the late Early Cambrian Kalladeina Formation to Ordovician Innamincka Formation and Dullingari Group. Middle and Late Cambrian acritarchs contain mainly long-ranging micrhystrids and leiosphaerids, whereas the Early Ordovician sediments produce abundant morphologically complex acritarchs. Three distinct assemblages can be divided, probably ranging from the early Tremadocian to late Arenigian. The acritarch biostratigraphy provides an additional aid to subcrop correlation and seismic interpretation, particularly in siliciclastic sequences. EARLY TREMADOCIAN ACRITARCH ASSEMBLAGE Tremadocian acritarchs were collected from the transitional beds between the Kalladeina and Innamincka formations in three wells, which contain mainly laminated siltstone with thin oolitic limestone, sandstone, and bioclastic carbonate or Nuia grainstone. This assemblage is equivalent to the early Tremadocian conodonts Yosimuraspis / Asaphellus and Cordylodus angulatus Zones (SUN & JAGO 1996) and is considered to have been deposited in an open, shallow marine shelf environment. Acritarchs are abundant in dark-grey siltstone and more than 30 forms were assigned to this assemblage which is dominated by two species: Leiofusa squama and L. stoumonensis. Other associated species include Baltisphaeridium cerimun, Clavitrichoides sp., Micrhystridium sp., Athabascaella sp., Leiosphaeridia sp. etc. This assemblage may range back to the Late Cambrian. LATE TREMADOCIAN TO EARLY ARENIGIAN ASSEMBLAGE This assemblage was collected from the Innamincka Formation in four wells and is facies-controlled. Open marine sediments contain many typical Early Ordovician acritarchs, such as Aryballomorpha grootaertii, Athabascaella penika, Athabascaella rossii, Athabascaella playfordii, Tongzia meitana, Stelliferidium cf. S. cylindratum and Cymatiosphaera cf. C. notialis. These forms have been recorded from the Tremadocian to Arenigian in eastern Europe, Canada and China. At same stratigraphic level, the inter-bedded limestone in Packsaddle 1 contains early Arengian conodonts (COOPER 1986). The Innamincka Formation is considered to have been deposited in a tidal-influenced delta complex (ZANG 1993) and depositional facies range from pre-delta open marine deposits, prodelta, subtidal delta front and intertidal delta flat settings. Acritarch assemblages from the open marine deposits contain index species suitable for biostratigraphic correlation, whereas the assemblages from onshore intertidal deltaic deposits are dominated by cyanobacterial filaments, those in the nearshore subtidal settings by spheroids, and relatively offshore or deeper prodeltaic sediments contain mixed spinose and spheroidal forms. The assemblages from the prodeltaic sequence can correlate with those from the open marine deposits. Generally, deeper or relatively offshore assemblages are likely to contain more diverse acritarchs than those from the nearshore, shallower and turbulent environments. LATE ARENIGIAN ASSEMBLAGE This assemblage was collected from the Mt. Crispe 1 well in the western Warburton Basin (Eringa Trough), where the basin is transitional to the Amadeus Basin, Northern Territory. Two samples from core 2 in the well were processed for acritarch study and the assemblage is dominated by leiosphaerids. The presence of species Virgatasporites sp., Gorgonisphaeridium sp. cf. G. miculum, Micrhystridium? acuminosum, Buedingiisphaeridium sp. cf. B. tremadocum and chitinozoan Velatachitina sp. indicates a possible late Arenigian age (CRAMER & DLEZ 1977; AL-HAJRI 1995). 134

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Early Ordovician acritarchs are widely reported around the world, but rarely investigated in South Australian basins. The three acritarch assemblages from the Warburton Basin can be correlated with those from England, eastern Europe, Canada, China and other places (RASUL & DOWNIE 1974; RASUL 1979; MARTIN 1984; YIN 1986; LI, 1987; MARTIN & YIN 1988; MARTIN 1992; MOLYNEUX et al 1996).

REFERENCES AL-HAJRI, S. 1995. Biostratigraphy of the Ordovician chintinozoa of northwestern Saudi Arabia. Review of Paleobotany and Palynolog,y 89: 27-48. COOPER, B. J. 1986 A record of Ordovician conodonts from the Warburton Basin, South Australia. Quarterly

Geological Notes, Geological Survey ofSouth Australia, 100: 8-14.

CRAMER, F. H. AND DLEZ M. de. C. R. 1977. Late Arenigian (Ordovician ) acritarchs from Cis Saharan,

Morocco. Micropaleontology, 23: 339-360.

LL JUN, 1987. Ordovician acritarchs from the Meitan Formation of Guizhou Province, south-west China. Palaeontology, 30: 613-634. MARTIN, F. 1984. New Ordovician (Tremadoc) acritarch taxa from the middle member of the Survey Peak

Formation at Wilcox Pass, southern Canadian Rocky Mountains, Alberta. Geological Survey of Canada. Currrent Research A, Paper 84-1 A: 441-448.

MARTIN, F. 1992. Uppermost Cambrian and Lower Ordovician acritarchs and Lower Ordovician chitinozoans

from Wilcox Pass, Alberta. Geological Survey of Canada. Bulletin, 420: 57p.

MARTIN, F. & YIN LEI-MING 1988. Early Ordovician acritarchs from southern Jilin Province, north-east China.

Palaeontology\ 31: 109-127.

MOLYNEUX, S. G., HERISSE, A. LE. & WISCANDER, R. 1996. Chapter 16. Paleozoic phytoplankton. In: J.

Jansonius and D.C. McGregor, (eds.), Palynology: principles and applications. American Association of Stratigraphic Palynologists Foundation. V. 2: 493-529.

RASUL, S. M. 1979. Acritarch zonation of the Tremadoc series of the Shineton Shales, Wrekin, Shropshire, England. Palynology, 3: 53-72. RASUL, S. M. & DOWNIE, C. 1974. The stratigraphic distribution of Tremadoc acritarchs in the Shineton Shales

succession, Shropshire, England. Review ofPaleobotany and Palynology, 18:1-9.

SUN X. 1996. Sequence stratigraphy, sedimentology, biostratigraphy and palaeontology of the eastern Warburton Basin (Palaeozoic), South Australia. Ph.D. thesis, University of Adelaide, 313p, 2 Vols, (unpublished). SUN X. & JAGO, J. B. 1996. Middle Cambrian to Early Ordovician biostratigraphy and application to sequence

stratigraphy, eastern Warburton Basin, South Australia. Geological Society ofAustralia, Abstract, 41:425.

YIN LEI-MING, 1986. Acritarchs. In: Chen Jun-Yuan (eds.), Aspects of Cambrian - Ordovician Boundary in

Dayangcha, China (Contribution to Dayangcha International Conference on Cambrian - Ordovician Boundary). China Prospect Publishing House, Beijing, p.314-373.

ZANG, WEN-LONG 1993. Early Ordovician tidal-influenced deltaic deposits and petroleum reservoirs, eastern Warburton Basin, South Australia. South Australia. Department of Mines and Energy. Report Book, 93/25.

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GRADIENT ANALYSIS OF MID ASHGILL BRACHIOPOD BIODIVERSITY IN EAST CHINA ZHAN REN-BIN1 and RONG JIA-YU1 1

Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing 210008, China

In the border region of Zhejiang and Jiangxi provinces, E China, middle Ashgillian rocks are well developed, amongst which three main lithofacies can be distinguished with various shelly faunas of different diversities, respectively. On the basis of over 25,000 fossils from 180 samples from 13 contemporaneous sections, seven brachiopod-dominated associations, the Ectenoglossa minor bivalve Association, the Eospirifer praecursor Association, the Altaethyrella zhejiangensis Association, the Antizygospira Association, the Tcherskidium jiangshanensis Association, the Kassinella-Epitomyonia Association and the Foliomena folium Association, are recognized and described statistically from these rocks typified at different localities of this area on the South China Palaeoplate. The Antizygospira Association is divided into two sub-associations, the Sowerbyella sinensis Sub-association and the Wangyuella-Tashanomena Sub-association. The species diversities, species densities, prevalent species and community distinctness coefficients are significantly different from association to association. Comprehensive synecological analysis, building on the palaeogeographic reconstruction suggested by earlier workers, shows that there existed an ecological pattern of nearshore shallow-water to offshore deep-water associations from Zhuzhai, Yushan County to Shangwu, Jiangshan County, during the Late Ordovician, while the brachiopod species diversities increase from Zhuzhai (close to the shoreline) to Daqiao, Jiangshan County (top part of the Zhexi Slope), but decrease sharply northeastward to Mulinlong and Shangwu (lower part of Zhexi Slope). Some vertical changes in species diversity are also well manifested by the community successions and replacements within several well-studied sections, showing changes in depositional environment. The palaeoshoreline trended northwest to southeast in this area rather than southwest to northeast as formerly thought. The primary control on the distribution of the different associations and the changes in species diversity was the water-depth, but some different associations could also develop on different substrates in similar water-depths.

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MIDDLE ORDOVICIAN CONODONTS FROM THE STOKES SILTSTONE IN THE AMADEUS BASIN (CENTRAL AUSTRALIA) JIANHUA ZHANG1,CHRISTOPHER R. BARNES1 and BARRY J. COOPER2 1

School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3055, Victoria, British Columbia, Canada, V8W 3P6, zhangj@uvic.ca, crbarnes@uvic.ca: Geological Survey of South Australia, Eastwood, South Australia 5063, Australia

A systematic sampling for conodonts was undertaken through the lower part of the Stokes Siltstone in the Amadeus Basin (central Australia). Over 7300 conodont elements have been recovered from 33 samples of the two sections, one at east end of Johnny Creek Anticline and another section at Stokes Pass which is the type locality for the Stokes Siltstone. The conodonts from the Stokes Siltstone are assigned to 27 species representing 18 genera. The conodont fauna is dominated by species of Phragmodus n. sp. and Oulodus oregonia, (60% total fauna). Several other species of mainly North American Midcontinent affinity are represented through the sequence, including Amelia nevadensis (ETHINGTON & SCHUMACHER), Erismodus quadridactylus (STAUFFER), Erismodus typus (BRANSON & MEHL), and Staufferella divisa SWEET. Also present are Drepanoistodus suberectus (BRANSON & MEHL), Panderodus gracilis (BRANSON AND MEHL), Erraticodon balticus DZIK. At least four species have North China biogeographic affinities: Aurilobodus aurilobodus (LEE), Oistodus sthenus ZHANG, Panderodus nogamii (LEE), Plectodina n. sp., which was derived from Plectodina onychodonta AN & Xu, and Triangulodus changshanensis ZHANG. One new genus and six new species are recognized: Amophoganthus n. sp. A, Phragmodus n. sp., Plectodina n. sp., Paraprioniodus n. sp., N. gen. and n. sp. 1, and N. gen. and n. sp. 2. The conodont succession in the lower part of the Stokes Siltstone is divided into three successive conodont zones: in ascending order they are, the Erismodus typus, Erismodus quadridactulus, and Phragmodus n. sp. zones. These three biostratigraphically distinct levels extend through an interval equating with three North American Midcontinent zones (SWEET 1984): the Plectodina aculeata, Erismodus quadridactylus, and Phragmodus undatus zones, and equate with the North China Tasmanognathus sishuiensis-Erismodus typus Zone (AN & ZHENG 1990). Based on the conodont fauna, the lower part of the Stokes Siltstone is considered late Gisbornian (late Middle Ordovician) in age. The conodont fauna and sedimentology indicate that the lower part of the Stokes Siltstone was deposited under low latitude, shallow-water conditions. REFERENCES AN, T . - X . & ZHENG, X.-C. 1990. The conodonts of the marginal areas around the Ordos Basin, North China.

Science Press of China, Beijing, 201 p., pi. 17. (In Chinese with English abstract) SWEET, W.C. 1984. Graphic correlation of upper Middle and Upper Ordovician rocks, North American Midcontinent Province, U.S.A. In D.L. Bruton (ed.), Aspects of the Ordovician System. 23-35. Palaeontological Contributions from the University of Oslo, 295. Universitetsfolaget.

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BIOFACIES PARTITIONING AND RESPONSE TO EUSTATIC CHANGES OF LLANDOVERY (EARLY SILURIAN) CONODONTS, ANTICOSTI BASIN, QUEBEC, CANADA SHUNXIN ZHANG and CHRISTOPHER R. BARNES School of Earth and Ocean Sciences, University of Victoria, P. O. Box 3055, Victoria, B.C. V8W 3P6, Canada, zhangs@uvic.ca« crbarnes@uvic.ca Anticosti Island, located in the Gulf of St. Lawrence, is underlain by Upper Ordovician (Ashgill) and Lower Silurian (Llandovery) strata of the Vaur^al, Ellis Bay, Becscie, Merrimack, Gun River, Jupiter and Chicotte formations. The entire sequence is represented by richly fossiliferous limestones and minor shales and siliciclastic sediments, totalling about 800-1100m in thickness. During the Early Silurian, the Anticosti Basin was situated at palaeolatitudes of 15-20° south of the equator, and on the northwest margin of the Iapetus Ocean. Most of the Upper Ordovician and Lower Silurian sediments were deposited in a restricted, shallow, storminfluenced, open-marine sublittoral environment with virtually no stratigraphic breaks. Other workers have recently developed a sea-level curve based on macrofossil and lithological data for Anticosti Island's Llandovery sequence. In order to examine how the changes in conodont faunas responded to sea-level changes, a statistical analysis was used to define the conodont biofacies groups. The database for this study consists of 41 conodont species derived from 123 samples collected from the lowest Becscie Formation to the exposed uppermost Chicotte Formation. Biofacies analysis employed cluster analysis of species abundance data and was performed by SPSS version 6.1 for the Macintosh [SPSS, 1994]. Pearson's correlation coefficient was used as an index of similarity and clusters were formed using the within-groups linkage method. Twelve biofacies can been recognized by both Q-and R-type dendrograms. This allows an interpretation as to how the changes in biofacies groups responded to eustatic changes throughout the Llandovery and how they compare to similar changes in benthic brachiopod communities. Some of the principal results of the analysis indicate that: 1) During periods of stable sea-level, conodont biofacies underwent minimal change. For example, the sea-level curve exhibits a moderate and stable depth from early to middle Aeronian (middle-upper Gun River Formation) during which the Icriodella deflecta-Oulodus jeannae-Ozarkodina pirata biofacies predominated, and the conodont fauna had high species diversity and high abundance. 2) During periods of relatively high sea-level, conodont biofacies had low species diversity and low abundance. The most common conodont biofacies is the Panderodus unicostatus biofacies, which recurred throughout the Becscie and Chicotte formations. This biofacies is characterized by relatively low species diversity and low abundance, and it is almost always related to brief intervals of relatively high sea-level. 3) During intervals of relatively low sea-level, conodont biofacies are characterized by high species diversity and abundance. The brief occurrence of the Pterospathodus siluricus-P. celloni-Aulocognathus bullatus biofacies in the upper Jupiter and lower Chicotte formations shows high species diversity and abundance and is associated with a period of lower sea-level. 4) Changes in conodont biofacies are not just related to changes in sea level. In a separate investigation using an additional 100 samples from specific sections in the Becscie, Gun River and Jupiter formations, in which the different microfacies were all sampled, it is evident that some conodonts show strong preference for particular lithofacies in a manner that cannot be explained simply through post-mortem redistribution of conodont elements. The generalized results noted above must be qualified by the overall pattern of radiation and by the three phases of faunal diversification exhibited by Llandovery conodonts after the major terminal Ordovician extinction event.

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EARLY ORDOVICIAN (BENDIGONIAN) CONODONTS FROM CENTRAL NEW SOUTH WALES, AUSTRALIA YONG-YI ZHEN1, IAN G. PERCIVAL2 and BARRY D. WEBBY1 1

Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Specialist Services Section, Geological Survey of New South Wales, P.O. Box 76, Lidcombe, NSW 2141, Australia

The first Bendigonian conodont fauna recorded from central New South Wales, comprising 16 species, is described and illustrated. The fauna occurs in laminated calcareous siltstones and allochthonous limestones of the Hensleigh Siltstone, exposed in the Bakers Swamp district 28 km south of Wellington. Both carbonate lithologies are interpreted as having been deposited in a lower slope graptolitic siltstone facies, the early Bendigonian age of which is given by a fauna comprising Didymograptus asperus, Dichograptus maccoyi, and Pendograptus sp. The exceptionally rich and well-preserved conodont fauna (Colour Alteration Index of 1.5-2) is contemporaneous with these graptolites. Juanognathus variabilis (32%), Acodus comptus (19%), Bergstroemognathus extensns (14%), Drepanodus arcuatus (7%), Reutterodus andinus (6%) and Acodus sweeti (6%) dominate the conodont assemblage, which is comprised of cosmopolitan, "temperate water" taxa, and is lacking in typical shallow, warm water forms. Given the assumed low-latitude palaeogeographic position of the region in Early Ordovician time, this is atypical of what might have been expected. The New South Wales fauna can in fact be most closely correlated with deeper, cooler water faunas from Precordilleran Argentina, South China, and from platform margin or slope settings of eastern North America and the western margin of North China. The fact that the Hensleigh assemblage (and its correlatives) cannot be indubitably assigned to either of the two Ordovician conodont palaeobiogeographic realms (Mid Continent, and North Atlantic) highlights a problem in definition of these faunal groupings as separate biogeographic entities. Some conodont taxa which are otherwise characteristic of the cool water North Atlantic province were present not only in high latitude regions, but also are found in cool deep water environments surrounding margins of continental blocks and islands in low latitudes. Shallower, and hence warmer waters, atop continental platforms in these latter areas, are the domain of fauna of the Mid Continent realm. Hence, rather than constituting purely spatial entities, these realms would be better defined as ecological (depth and temperature-determined) distributions with an endemic overprint, comprising (1) a high latitude, cool shallow water fauna, and (2) a low latitude, warm shallow water fauna; with an additional largely cosmopolitan grouping of (3) deeper, cooler water fauna of global extent. [Published with permission of the Director General, NSW Department of Mineral Resources. This is a contribution to IGCP 410 "The Great Ordovician Biodiversification Event".]

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LLANVIRN-EARLY CARADOC TRILOBITE BIOFACIES OF WESTERN HUBEI AND HUNAN, CHINA ZHIYI ZHOU1, ZHIQIANG ZHOU2 and WENWEI YUAN1 1 2

Nanjing Institute of Geology & Palaeontology, Academia Sinica, Nanjing 210008, China Xi'an Institute of Geology & Mineral Resources, Xi'an, 710054, China

Llanvirn-early Caradoc trilobite faunas display a progressive transition in composition and diversity from southwestern Hubei to southwestern Hunan, with benthic forms decreasing and mesopelagic taxa increasing gradually southwards. On the basis of representative collections made from seven measured sections, three Llanvirn and five Llandeilian-early Caradoc trilobite biofacies are distinguished along a shallow- to deep-shelf gradient. In the Llanvirn, the shallow outer shelf Nileid Biofacies is recognised in the Yichang and Cili areas. Trilobites occurring in biocalcilutites (basal part of the Pagoda Formation) include species assigned to 9 (Cili) and 12 (Yichang) genera and subgenera. Only a few mesopelagic cyclopygids, Microparia (s. I.), are associated. Similar biocalcilutites are also distributed in the Rishi area, south of Cili, but trilobites there are referred to the NileidMicroparia (Quadratapyge) Biofacies. This is characterised by the occurrence of rich M (Quadratapyge) as compared with the preceding biofacies. This mesopelagic subgenus makes up more than 50% of the total specimens in the Rishi collection, indicating a deep outer-shelf setting. Further seawards, this biofacies is replaced in the Changde area by the Raphiophorid-M (Quadratapyge) Biofacies, occurring in graptolite-bearing calcareous shales (upper part of the Jiuxi Formation). M (Quadratapyge) is most abundant. Of benthic forms, raphiophorids are numerically predominant, but nileids become rare, suggesting a muddy substrate. No Llanvirn trilobites have yet been found in condensed black graptolite shales in the Taojiang and Qidong areas, south of Changde, though a quiet shelf depositional environment is suggested by geochemical data. In the Llanvirn-early Caradoc, two different trilobite faunas developed in shallow outer-shelf environments. Trilobites of the Birmanites-raphiophorid Biofacies occur in black graptolite shales and muddy limestones (Miaopo Member of the Pagoda Formation) in the Yichang area. Generic diversity varies from 16 (Daping) to 18 (Huanghuachang). Except for the epipelagic Telephina, all are benthos, including mainly asaphids and raphiophorids. Lithologic and taphonomic evidence indicates that this fauna may have lived on a soft muddy substrate under quiet conditions. Trilobites of the Hexacopyge Biofacies are distributed in biocalcilutites (lower part of the Pagoda Formation) in the Cili area, with a generic (subgeneric) diversity of 18. Numerically, the fauna is dominated by remopleurids, with significant numbers of nileids, raphiophorids and proetids, and a few cyclopygids. Along the deep shelf slope, three biofacies are recognised in gradually deepening water. The M (Quadratapyge)-Hexacopyge Biofacies is present in biocalcilutites (lower part of the Pagoda Formation) of the Rishi area. Among ten genera and subgenera, the cyclopygid M. (Quadratapyge) accounts for more than 60% of total collected specimens; all six benthic genera, including Hexacopyge and Ovalocephalus, amount to only about 30%. The Cyclopyge-Cyamella Biofacies is developed in argillaceous limestones (lower part of the Pagoda Formation, corresponding to the Prioniodus alobatus conodont Zone) of the Changde area. Cyclopyge predominates over all six other trilobite forms; of four benthic genera, only the rorringtoniid Cyamella is numerically significant. The Cyclopygid Biofacies appears further southwards to the Taojiang and Qidong areas. Only pelagic (chiefly mesopelagic) forms were found in association with graptolites in the basal Modaoxi Formation and lower part of the Shuangjiakou Formation.

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CONODONT RESPONCE TO THE MID-VISEAN (EARLY CARBONIFEROUS) ECOLOGICAL EVENT A.V. ZHURAVLEV All-Russian Geological Research Institute, St.Petersburg, Russia. Mid-Visean ecological event is recognized as being short term eustatic regressive-transgressive couplet at the base of the Gnathodus bilineatus conodont zone (approximately corresponds to the base of Mestognathus bipluti conodont zone for shallow-water facies and Endothyranopsis crassa foraminifer zone). U. Brand reported some temperature increasing at this level. Kozhym River section (Polar Urals) is proposed as a type section of the Mid-Visean event. There the level is represented by cherty layers in the facies of open carbonate platform characterized by conodonts, foraminifers, and rugose corals. Biotic appearance of the event is represented by ecological recovery of conodont associations in both the shallow-water and deep-water environment, flourishing of the benthic communities, recovery of nonWaulsortian bioherms having true framework niche, minor radiation in foraminifers, changes in coral and brachiopod diversity. The Mid-Visean event interrupted the well-known Visean lower-diversity episode in conodont evolution (ZLEGLER & LANE 1985). Conodont species diversity increased from 4 species in texanus Zone (=beckmanni Zone) up to 10 species in the bilineatus Zone (=bipluti Zone) (data for the North Urals region). Despite of increasing in conodont fauna endemism in the Visean, the event led to wide spreading of the pandemic species, such as Mestognathus bipluti, M. beckmanni, Gnathodus bilineatus, G. girtyi, and Lochriea commutata. These species are known in both the Palaeotethys and Palaeopacific realms. Mid-Visean event can be traced over the world: in the Upper Meramecian (N. America), in the middle of the Genicera Formation (Spain), at the base of the Warnantien (V3b) (Belgium), at the Holkerian/Asbian (UK), Middle Tulskian (North of Urals and Russian Platform), etc. So, the event has high correlation potential. This work is supported by the RFBR grant 99-05-65290.

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A STUDY OF BELODELLA AND NEOPANDERODUS WITH EMPHASIS ON FAUNAS FROM EASTERN AUSTRALIA MARGARET ANDERSON Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW. 2109, Australia In order to probe the biostratigraphic utility of the genera Belodella and Neopanderodus, conodonts frequently recovered from shallow water limestones (sometimes to the exclusion of platform elements with recognised biostratigraphic significance), a study of the occurrence of the two forms within Australia has been undertaken. The genus Belodella ETHINGTON, 1959 includes very fragile, coniform conodonts with a deep basal cavity and laterally compressed denticles along the posterior margin. Originally, these forms were referred to Belodus, an Ordovician taxon. The genus Neopanderodus ZLEGLER and LLNDSTROM, 1971 includes coniform conodonts that possess longitudinal striae and a less well developed wrinkle zone around their base compared to the more wellknown genus Panderodus. Recent studies of faunas from eastern Australia, extending from the Broken River Province in North Queensland southwards through the Tamworth Belt and the Wellington areas of New South Wales, the Buchan-Bindi area and Boola-Tyers-Coopers Creek area in east-central Victoria, have highlighted the shallow-water occurrence of the genera Belodella and Neopanderodus. Belodella ranges in age from Late Silurian [siluricus Zone] to Middle Devonian [varcus Zone], but Neopanderodus has a narrower range generally from Early Devonian [delta Zone] to Middle Devonian [hermanni Zone] apart from two specimens, one from Victoria, Australia (SIMPSON 1995) and the other from the central Jilin Province, China (WANG & Li 1986) that have been recorded from the Silurian. Multi-element taxonomy has been applied to the genus Neopanderodus with the recognition of Sa, Sb, Sc, M and T elements. Neopanderodus aequabilis is restricted between the base of the inversus Zone to the top of the hermanni Zone. A new species, Neopanderodus leptostriatus is restricted to the sulcatus-pesavis zones. REFERENCES ETHINGTON, R.L. 1959. Conodonts from the Ordovician Galena Formation. Journal of Paleontology, 33(2): 2 5 7 292. SMPSON, A.J. 1995. Silurian conodont biostratigraphy in Australia: a review and critique. Cour. Forsch. Inst.

Senckenberg, 182: 325-345. C.-Y & Li, D.-Y. 1986. Conodonts from the Ertaoguo Formation in central Jilin Province. Acta Micropalaeontologica Sinica, 3: 421-428 [in Chinese].

WANG,

ZlEGLER, w. & LlNDSTROM, M.

1971. Uber Panderodus ETHINGTON (1959), and Neopanderodus new gen. (Conodonta) aus dem Devon. NeuesJahrb. Geol. PalaentoL, 1971: 642-640.

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RECOVERY OF LATE DEVONIAN FLORA FROM KERMAN AREA, SOUTH EAST IRAN MAJID MIRZAIE ATAABADI and KARAM ALIRAHMANI Department of Geology, Faculty of Sciences, University of Esfahan, Iran Late Devonian flora were first reported by GOLSHANI et al. (1972) from Bidu Cliff section in northern Kerman. They assigned the flora remains as Heleniella theordi ZAIESSKY and Lepidosigillaria whitei KRAUSEL & WEYLAND. HARNDI & ZHEWEN (1995) reported Sigillaria persica SEWARD from the basal quartzites of Late Devonian succession in Ab-e-Morad section, eastern Kerman. WENDT et al (1997) found lycophyte remains from red and white crossbedded sandy and quartzitic horizons, near Hojedk in northern Kerman, which they referred them to cf Lepidodendropsis in Lower asymmetricus CZ (Frasnian). New plant remains were recovered from a red sandstone bed in Kuh-e-Gowdechah section, 40 Km south of Ravar, northern Kerman. Based on brachiopod taxa from upper horizons the flora which comprises Sigillaria sp., aff. Archaeosigillaria, and unassigned plant remains, could roughly be attributed to Middle Frasnian. This level will be checked by conodont biostratigraphy for more accurate age in future. The flora horizons will be used as a key for correlation of basal Late Devonian continental crests in Iran, specially Central Iran which related to ancient northern Gondwanan terranes. REFERENCES RAHMANI, K.A. 1999. Biostratigraphy of Late Devonian Brachiopods in Kuh-e-Gowdechah section, north of

Kerman. University ofEsfahan, Unpublished M.Sc thesis, 150pp.

BERRY, C.M. & EDWARDS, D. 1997. A new species of thelycopsid Gilbophyton Arnold from the Devonian of

Venezuela and New York State, with a revision of the closely related genus Archaeosigillaria KidstoYi. Review of Paleobotany and Palynology, 96: 47-70.

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DEVONIAN OF SHAN STATE, MYANMAR AYE KO AUNG Department of Geology, Dagon University, Myanmar For many years, very limited occurrences of Devonian strata have been known in Myanmar. In recent years, more than ten new localities of Devonian fossils have been recorded from both northern and southern Shan State. Devonian strata occur in four major areas: in northern Shan State, Zebingyi arid Padaukpin; in Pyin-Oo-Lwin (formerly Maymyo) township; in southern Shan State, Taunggyi town area in Taunggyi Township, and Myozo area in Kalaw and Lawksawk Township. The oldest recognised Devonian unit is the Zebingyi Formation (late Pragian-?early Emsian). which occurs in the Zebingyi, Taunggyi, and Myozo areas. This formation reflects slow pelagic sedimentation in a deep water, low energy environment below wave base, which was locally affected by intermittent storms. Following a period of slight erosion, deposition recommenced in the Eifelian in the Padaukpin and Kyadwinye areas where the limestones were laid down as distinct biostromal beds (CUMMINGS 1932). No Padaukpin equivalent unit or Devonian biostromal limestone is known from southern Shan State. In type area, the Zebingyi Formation can be subdivided into two upper and the lower members. The upper member consists of thin partings of yellow to earthy shale characterised by species of dacryoconarid tentaculites associated with trilobites, brachiopods, cephalopods and bivalves. The lower member comprises dense black limestone separated by layers of light-coloured purple, black shale crowded with dacryoconarids. graptolites, and brachiopods. Although the formation is richly fossiliferous little has been published on the faunas. REED (1908) described the Devonian faunas of northern Shan State. JAEGER (1983) studied the lower Devonian graptolites from Pyin-hsa area in Pyin-Oo-Lwin Township. WOLFART et al (1984) made a list of possible equivalents of the Zebingyi Formation in southern Shan State. AUNG (2000a) first reported Devonian limestones with abundant dacryoconarids from Taunggyi-Taungchun Range. More Devonian outcrops (about 5) in the vicinity of Taunggyi town area have been subsequently recognized (AUNG 2000b). The dacryoconarids from Taunggyi town area are closely similar to those from the Mahang Formation in northwest Malaya (BURTON 1967). The brachiopod fauna of the Zebingyi Formation includes Plectodonta from the Paungdaw area, and has also been recovered form the contemporary Pa Samed Formation, southern Thailand (BOUCOT et al. 1999). The Padaukpin biostrome consists of light to dark grey dolomitic limestone, commonly associated with loose muddy particles, in places interbedded with thin shales. The unit is fossiliferous, containing rugose and tabulate corals, brachiopods, sponges, bryozoans, conodonts, foraminifera, echinoids, blastoids, ostracods, and dacryoconarids. The Padaukpin corals collected by LA TOUCHE (1913) were identified by REED (1908) who recognized 23 rugose and 21 tabulates species. REED (1929) described four rugose and seven tabulate species from the neighborhood of Padaukpin. ANDERSON et al. (1969) made a large collection of fossils from the Padaukpin area and described eight new species of Eifelian brachiopods. AUNG (1995) described eight new species of Eifelian rugose corals from Pwepon, a small village located 5 km east of the Kyadwinye iron mine in northern Shan State. No undoubted Givetian or Upper Devonian faunas have been recognised in Myanmar and in most cases, the Eifelian Padaukpin unit directly underlies the Maymyo dolomite (AMOS 1975). REFERENCES AMOS, B. J. (1975). Stratigraphy of some Upper Paleozoic and Mesozoic carbonate rocks of the eastern Highlands.- Newsl. Stratigr., 4 (1): 49-70. ANDERSON, M. M., BOUCOT, A. J., AND JOHNSON, J. G. (1969). Eifelian brachiopods form Padaukpin, northern

Shan State, Burma.- Bulletin of the British Museum of Natural History, 18: 107-163. AUNG, A. K. (1995). New Middle Devonian (Eifelian) rugose corals from Myanmar.- Journal Southeast Asian Earth Science, 11 (1): 23-32. AUNG, A. K. (2000a). A short note on recent discovery of tentaculite-bearing unit form Taunggyi-Taungchun

range, southern Shan State, Myanmar.- Abstracts and Papers. Annual Paper Reading and Prize Presenting Ceremony in Memory ofDr Myint Lwin Thein (Jan. 2000): 15-18. AUNG, A. K. (2000b). Devonian outcrops around Taunggyi, southern Shan State, Myanmar.- J. Geol. Dagon

Uni., Geology Association (in prep.) 144

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BOUCOT, A. J., COCKS, L. R. M., AND RACHEBOEUF, P. R. (1999). Early Devonian brachiopods from Satun

Province, southern Thailand.- Journal ofPaleontology, 73 (5): 850-859.

BURTON, C. K. (1967). The Mahang Formation: a Mid Paleozoic euxinic fades from Malaya- with notes on its

conditions of deposition and paleogeography.- Geol. En. Minjnb46: 167-187.

CUMMINGS. E. E. (1932). Reefs or Bioherms? Bull. Geol.-Soc. Am., 43: 331-352.

JAEGER, H. (1983). Underdebonische graptolithen aus Burma.- Jb. Geol., 126 (2): 245-257. La TOUCHE. T. H. D. (1913). Geology of the northern Shan States.- Mem. Geol. Surv. India, 39 (2): 397 pp.

REED. F. R. C. (1908). The Devonian faunas of the northern Shan States.- Mem. Geol. Surv. India {Paleont. Indical 2: 1-183. REED. F. R. C. (1929). An Upper Devonian faunafromthe neighborhood of Padaukpin, northern Shan States.Rec. Geol. Surv. India, 62 (2): 229-248. WOLFART, R. U., U MYO MIN, SAW BOITEAU, U MYO WAI,U PETER UK CUNG, AND U THIT LlN (1984).

Stratigraphy of the western Shan Massif, Burma.- Geol. Jahr. Reihe. B. Regionale Geologie Ausland, 57: 95 pp.

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SILURIAN STRATIGRAPHY AND PALAEOGEOGRAPHY OF BALTICA B. GUDVEIG BAARLI1, MARKES E. JOHNSON1 and ANNA I. ANTOSHKINA2 'Geosciences Dept., Williams College, Williamstown, MA 01267, USA; institute of Geology, Komi Science Centre, Uralian Division of the Russian Academy of Sciences, Skytyvkar, Russia Approximately 7.8 million km2 in total area, the palaeocontinent of Baltica reveals only a miniscule record of its former marine shelves and cratonic depressions in surviving exposures of fossil-rich Silurian strata. Combined with a more extensive record of Silurian strata in the subsurface, however, it is possible to convert compatible palaeontological and lithological information from key sequences into reliable bathymetric profiles. Backed by a wealth of auxiliary information, 25 bathymetric logs from the Central Scandinavian, East Baltic, Dnestr River, and Timan-Pechora regions of northern Europe, Bylerussia, the Ukraine, and northwestern Russia enable the reconstruction of a series of palaeogeographic maps that cover approximately 30% of Silurian Baltica. Maps for various time slices through the Llandovery, Wenlock, and Ludlow series show that sedimentation in the Central Scandinavian depression and adjacent East Baltic Basin was strongly influenced by the Scandian orogeny to the west and the docking of the micro-continent Avalonia on the southwest. Compilation and interpolation of map data for these sectors yield a more comprehensive model for tectonic influences on the evolution of marine shelves and epicontinental basins. The prevalent tectonic signature of the region is a narrow foreland basin preceded by a peripheral bulge that advanced across Scandinavia from the northwest in Llandovery time. During later Wenlock and Ludlow time, central Scandinavia was deluged with clastics that ushered increasingly shallow-water conditions to a large region. Simultaneously, the down warping of the cratonic margin to the south due to the impingement of Avalonia brought about relatively deep-water conditions that long persisted in Denmark and Scania. A tongue of graptolitic shales advanced as far as Gotland in Llandovery time and remained somewhat longer in western Estonia through earliest Wenlock time, but accommodation space for thick accumulations of shale never developed to the same degree as in southern Scandinavia. By contrast, the Timan-Petchora depression in northwestern Russia sat on a comparatively passive cratonic shelf. Two distinct phases of expansive reef growth occurred behind a rimmed margin first during Late Llandovery time and again from mid-Wenlock until the start of Late Ludlow time. These episodes are roughly coeval with the record of at least two highstands in sea level often observed elsewhere in Upper Llandovery rocks and a highstand commonly recorded at the Wenlock-Ludlow transition. Against this regional background, the record of Silurian eustasy is surprisingly robust. Four out of eight eustatic peaks proposed by JOHNSON et al. (1998) are registered with some regularity in Baltica. All shelf regions were affected by the initial rise in sea level following the retreat of Late Ordovician glaciers in the North African and South American sectors of Gondwana. The first prominent highstand in sea level at or near the RhuddanianAeronian boundary is well represented in fully half of the profiles illustrated in this project that span the interval. A rapid rise in sea level that is particularly well exhibited in central Scandinavia and the East Baltic Basin is correlated with the Lower Telychian Spirograptus turriculatus zone. We surmise this event was not recorded in the Timan-Pechora region due to vigorous reef growth that kept up with rising sea level. A subsequent highstand at or near the Llandovery-Wenlock boundary is well recognized along an axis from Skien in southern Norway to JSmtland in west central Sweden, but is only poorly known in northwestern Russia. It is important to note that the Late Wenlock eustatic draw down in sea level is registered in more than half the profiles for that interval illustrated in this project. It is notable that half the cited Russian profiles pick up the Late Ludlow sea-level excursion, as do the profiles for Sk&ne and Gotland. Among the additional Silurian eustatic peaks proposed by LOYDELL (1989), the most promising for Baltica is that associated with the Pristiograptus parvus-Gothograptus nassa zone in the Upper Wenlock, Homerian Stage. REFERENCES JOHNSON, M.E., RONG J.-Y. & S.KERSHAW. 1998. Calibrating Silurian eustasy against the erosion and burial of

coastal paleotopography, p. 3-13. In E. Landing and M.E. Johnson (eds), Silurian Cycles -Linkages of Dynamic Stratigraphy with Atmospheric, Oceanic, and Tectonic Changes. New York State Museum Bulletin 491. LOYDELL, D . K . 1998. Early Silurian sea-level changes.- Geological Magazine, 135: 4 4 7 - 4 7 1 .

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THE MOST PRIMITIVE OSTEIGHTHYAN BRAINCASE? ALISON BASDEN Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia The Devonian Burrinjuck fossil fauna, recovered from numerous localities around the Burrinjuck Dam in southern New South Wales, is well known for its diversity and excellent preservation. Described forms include not only vertebrates (fish, dominantly placoderms, with lungfishes, other osteichthyan microremains, and acanthodians), but also a range of invertebrate taxa (trilobites, brachiopods, gastropods, bivalves, sponges, corals, conodonts, and ostracodes). One outstanding component of the Burrinjuck fauna is an actinopterygianlike braincase, from the Emsian (pireneae-serotinus conodont zones) Taemas Limestone at Wee Jasper. The specimen consists of an ornamented, anteriorly incomplete skull roof, attached to the surface ossification of the cartilaginous braincase. These are preserved in fine detail and show openings for cranial nerves, vessels, sensory canals, and the central cavity for the brain. The specimen displays a remarkable assemblage of characters. While the ornamentation of the dermal bone, the skull roof pattern, and the general proportion and structure of the endocranium are typically actinopterygian, other features more closely resemble endocrania of other fish groups (BASDEN et al. 2000). For example, the curved pit lines, the widely-separated orbital walls, the short, broad telencephalon cavity and the lateral span of the basisphenoid are typical of sarcopterygians. The position and orientation of the postorbital process and spiracular groove, and the attachment of the basisphenoid to the anterolateral face of the otic capsule, are similar to the condition in chondrichthyans, other actinopterygians and acanthodians, but unlike that in sarcopterygians. The position of the hyomandibular facet is similar to that in acanthodians. The insertion of the superior oblique eye muscle in the anterodorsal wall of the orbit is found in chondrichthyans and other osteichthyans, but not in placoderms. The slender canal carrying the pituitary vein is typical of placoderms. The most significant and surprising feature, however, is an eyestalk attachment area in the centre of the orbit, immediately behind the foramen for the optic nerve. Today this occurs only in sharks and rays, and in fossil fishes has been found only in placoderms and primitive chondrichthyans. This specimen is the first primitive osteichthyan to clearly show the presence of an eyestalk. The phylogenetic impact of this curious mix of characters is already controversial. Presence of an eyestalk supports the contention that this feature is primitive for gnathostomes, and so does not represent a synapomorphy (shared derived character) uniting placoderms and chondrichthyans, as has generally been accepted. Acanthodians are now the only major group in which the presence of an eyestalk has yet to be demonstrated. The new character mosaic displayed by the specimen leads to the intriguing possibility that it may be not just a primitive actinopterygian, but even perhaps a stem-group osteichthyan. If this is correct, then the Wee Jasper braincase is a missing link to our past, revealing primitive cranial conditions for not only the lineage ancestral to ray-finned fish, but also the lineage leading to lobe-finned fishes and ourselves. REFERENCE BASDEN, A.M., YOUNG, G.C., COATES, M.I. & RITCHIE, A. 2000. The most primitive osteichthyan braincase? Nature, 403: 185-188.

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TRANSITION FROM DIAGENESIS TO METAMORPHISM IN THE PALAEOZOIC SEQUENCES OF THE TOWNSVILLE HINTERLAND OF NORTHEASTERN AUSTRALIA COVADONGA BRIME1, JOHN A. TALENT2 and RUTH MAWSON2 1 2

Departamento de Geologfa, Universidad de Oviedo, 33005 Oviedo, Spain Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia

Transition from diagenesis to low grade metamorphism for the Ordovician-Carboniferous sequences of the Burdekin and Clarke River Basins and the Broken River and Camel Creek regions is characterised by illite crystallinity (IC), clay-mineral assemblages, and conodont colour alteration index (CAI). The general trend in all areas is for IC values to increase with ascending stratigraphic position (decreasing depth of burial) from epizone for the oldest stratigraphic units, eg. from the Judea, Wairuna and Pelican Range Formations, through low anchizone, eg. Perry Creek, Greenvale, Quinton (southern areas), Jack, Shield Creek and Stud Formations, to middle or high anchizone, eg. Myrtlevale, Hardwick, Quinton (northern areas), and Papilio Formations. Tracts of the Early Carboniferous (Tournaisian) upper Hardwick, Picadilly and Ruxton Formations of the Burdekin and Clarke River Basins fall within the diagenetic zone. Salient anomalies are explicable in terms of location relative to areas of differing intensity of deformation (eg. in the case of the Ruxton Formation), inferred greater depth of burial (notably in the case of southern versus northern outcrop tracts of Quinton Formation), or high flux of mineralising fluids, eg. for the Mytton Formation sampled at the Big Rush Mine. An overall burial depth of -9km and a palaeothermal gradient of ~30°C/km are indicated. CAI data for the Townsville hinterland indicate: 1. A generalised N-S increase in CAI for the Broken River region ('Top Hut' to Broken River); 2. E-W decrease in the western part of the Burdekin Basin. There appear to be three salient drops in thermal flux indicated by CAI data: 1. During the interval end Ordovician-Early Silurian (Llandovery); 2. Earliest Devonian, (mid-Lochkovian: broadly eurekaensis-delta Zones); 3. Middle Devonian (midMate Givetian: broadly between the Middle varcus and hermanni Zones).

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CHANGES IN MICROVERTEBRATE FAUNAL ASSOCIATIONS THROUGH THE LOWER DEVONIAN OF SOUTH-EASTERN AUSTRALIA CAROLE J. BURROW Dept of Zoology and Entomology, University of Queensland, Queensland 4072, Australia Changes in microvertebrate assemblages from Early Devonian marine limestones appear correlated with the pattern and timing of transgressions and regressions as proposed by TALENT (1989), MAWSON et al (1992), and TALENT et al. (1993). A preliminary analysis of these changes in the microvertebrate assemblages was given in TURNER & YOUNG (1997).

Earliest Devonian faunas are rare and usually species-poor, co-incident with the Derringullen-Bowning Regression following the S-D boundary event. The oldest described assemblage, from the Camelford Limestone (woschmidti-eurekaensis CZ; PARKES in BASDEN et al. 2000), comprises the acanthodian Poracanthodidae cf. Zemlyacanthus menneri* and acanthothoracid placoderms. Vertebrate microfaunas became more abundant by later in the Lochkovian: the Garra 1 Transgression (delta CZ) marked the incoming of acanthodian Ischnacanthidae? nov. gen. et sp.* (Garra and Windellama limestones; PARKES in BASDEN et al. 2000), associated with several acanthothoracid placoderms, and palaeoniscoid Terenolepis turnerae BURROW, 1995 in the upper delta-pesavis CZ of the Garra Limestone. This deeper shelf fauna is also found in the base of the Cunningham Formation. The ?ischnacanthid is missing from limestones (eg. Connemarra Formation) probably deposited during the later Garra 2 Transgression (upper pesavis CZ, cf. YOUNG 1995), replaced by acanthodians Trundlelepis cervicostulata BURROW, 1997 and "Nostolepis" guangxiensis, with the placoderms and T. turnerae still associated, plus ?osteichthyan Lophosteus incrementus BURROW, 1995 and an onychodontid with unstriated teeth. Co-eval near shore deposits, eg. the Tumblong Oolite, are dominated by thelodonts, Turinia spp., with acanthodians Trundlelepis cervicostulata* "Nostolepis" guangxiensis*, and Nostolepis sp. cf. N. striata also in the assemblage. These associations probably persisted into the early Pragian lower sulcatus CZ, with a gradual change during the mid-upper sulcatus CZ marked by the incoming acanthodian Gomphonchus? bogongensis BURROW, 1997 (Point Hibbs and Coopers Creek formations; BURROW etal. 1998). The deeper water Coopers Creek Formation fauna (BASDEN 1999) includes the acanthodian Radioporacanthodes sp. aff. R. liujingensis* associated with acanthothoracid and petalichthyid placoderms, with the acanthodian Nostolepoides platymarginata BURROW, 1997 appearing about the sulcatus/kindlei CZ boundary; these taxa persist through the kindlei CZ. The vertebrate record is otherwise poor through the mid Pragian, with assemblages becoming more common during the Buchan Caves Transgression, following the Red Hill Regression (pireneae CZ). G.l bogongensis and N. platymarginata persisted through the pireneae-dehiscens CZ in both near shore and deeper waters (Gleninga and Troffs formations, Buchan Caves Limestone), associated with the incoming palaeoniscoid Ligulalepis toombsi, chondrichthyan "Ohiolepis" sp., placoderm Goodradigbeeon sp. (BURROW 1994, 1997; BURROW & TURNER 1998), ?placoderm Kadunglelepis serrata BURROW, 1996, and thelodont Turinia sp. cf. T. australiensis (TURNER 1997). Samples from the pireneae CZ in the Jerula Limestone Member of the Gleninga Formation and the Troffs Formation are characterised by the placoderm Jerulalepis picketti BURROW, 1996. The earliest Emsian dehiscens CZ deeper water assemblages mark the first appearance of acanthodians Cheiracanthoides wangi (BURROW et al. 2000; BURROW in BASDEN et al. 2000), Cheiracanthoides sp. cf. C. comptus, and taemasacanthid spp. (LLNDLEY 2000), ptyctodont placoderms, and a dipnoan or porolepiform. A faunal change apparently occurred during the perbonus-inversus CZ, marked by the loss of the older pireneae CZ acanthodians, and the incoming of Gomphonchus? nov. spp.* and Nostolepis spp., and also Chondrichthyes nov. gen. et sp. (cf. TURNER 1993 - referred to Skamolepis by GIFFIN, 1980). The only samples examined from the latest Emsian (patulus CZ; Mount Frome Limestone) indicate a faunal change at the serotinus/patulus CZ boundary, with the only acanthodian being Cheiracanthoides comptus s.s. •taxa deemed present but not previously recorded. REFERENCES BASDEN, A.M. (1999) Early Devonian microvertebrates from the Tyers-Boola area of central Victoria, Australia. Bollettino della Societa Paleontologica Italiana, 37: 527-541. A., BURROW, C.J., HOCKING, M., PARKES, R. & YOUNG, G.C. (2000) Siluro-Devonian microvertebrates from south-eastern Australia. In A. Blieck & S. Turner (eds.) IGCP 328, Final Report. Courier Forschungsinstitut Senckenberg.

BASDEN,

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BURROW, C. (1994) Form and function in scales of Ligulalepis toombsi Schultze, a palaeoniscoid from the Early Devonian of Australia. Records of the South Australian Museum, 27(2): 175-185. BURROW, C.J. (1995a) A new palaeoniscoid from the Lower Devonian Trundle beds of Australia Geobios

Memoire Special, 19:319-325. BURROW, C.J. (1995b) A new lophosteiform (Osteichthyes) from the Lower Devonian of Australia Geobios Memoire Special 19: 327-333. BURROW, C.J. (1996) - Placoderm scales from the Lower Devonian of New South Wales, Australia Modern Geology, 20 (3/4): 351-369. BURROW, C.J. (1997) Microvertebrate assemblages from the Lower Devonian (pesavis/sulcatus zones) of central New South Wales, Australia. Modern Geology, 21 (1/2): 43-77. BURROW, C.J. & TURNER, S. (1998) Devonian placoderm scales from Australia Journal of Vertebrate Palaeontology, 18(4): 677-695. BURROW, C.J., LONG, J.A. & TURNER, S. (1998) Lower Devonian microvertebrates from Tasmania. Alcheringa, 22: 9-20. BURROW, C.J., TURNER, S. & WANG S-T. (2000) Devonian microvertebrates from Longmenshan, Sichuan,

China: Taxonomic assessment. In A. Blieck & S. Turner (eds.) IGCP 328, Final Report. Courier Forschungsinstitut Senckenberg. GIFFIN, E. (1980) Devonian vertebrates from Australia. Postilla, 180: 1-15.

LINDLEY, I.D. (2000) Acanthodian fish remains from the Lower Devonian Cavan Bluff Limestone (Murrumbidgee Group), Taemas district, NSW. Alcheringa, 24: 11-35. MAWSON, R., TALENT, J.A., BROCK, G.A. & ENGELBRETSEN, M.J. (1992) Conodont data in relation to

sequences about the Pragian-Emsian boundary (Early Devonian) in south-eastern Australia Proceedings of the Royal Society of Victoria, 104: 23-56. TALENT, J.A. (1989) Transgression-regression pattern for the Silurian and Devonian of Australia. In R.W. Le Maitre (ed.) Pathways in Geology - Essays in Honour of Edwin Sherbon Hills. Blackwells, Carlton, pp. 201219. TALENT, J.A., MAWSON, R., ANDREW, A.S., HAMILTON, P.J. & WHITFORD, D.J. (1993) Middle Palaeozoic

extinction events: faunal and isotopic data. Palaeogeography, Palaeoclimatology, Palaeoecology, 104* 139152. TURNER, S. (1993) Palaeozoic microvertebrate biostratigraphy of Eastern Gondwana. In J.A. Long (ed.) Palaeozoic Vertebrate Biostratigraphy and Biogeography. Belhaven Press, London, pp. 174-207. TURNER, S. (1997) Sequence of Devonian thelodont scale assemblages in East Gondwana Geological Society of America Special Paper, 321: 295-315. TURNER, S. & YOUNG, G.C. (1997) Devonian vertebrate faunal response to eustatic sea-level changes in East Gondwana. Courier Forschungsinstitut Senckenberg, 199: 117-127. YOUNG, G.C. (1995) Timescales calibration and development. 4. Devonian. Australian Phanerozoic timescales, biostratigraphic charts and explanatory notes. Second Series. AGSO Record 1 9 9 5 / 3 3 , 4 7 pp.

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THE GREATER GONDWANA DISTRIBUTION OF THE MIDDLE ORDOVICIAN CONODONT PANDERODUS NOGAMII (LEE, 1975) ROBIN C. CANTRILL and CLIVE F. BURRETT School of Earth Sciences, University of Tasmania, Box 252-79, Hobart, Tasmania 7001, Australia A distinctive species of Panderodus originally named Scolopodus nogamii LEE from North korea is also present in the Lower Ordovician of Malaysia, North and South China, Australia and Argentina. The species ranges stratigraphically through the Whiterockian and is restricted to shallow water carbonates within tropical to subtropical latitudes of Greater Gondwana. The biogeographic distribution of P. nagomii is similar to the gastropod Peelerophon oehlerti and the trilobite Asaphopsoides sp.

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SPONGE-CORAL MUTUALISM: A SILURIAN EXAMPLE? GARY DARGAN Geological Survey of New South Wales, P.O. Box 76 Lidcombe, N.S.W. 2141 Australia. An association between the colonial rugosan Entelophyllum and an unidentified stromatoporoid is interpreted as a possible example of mutualistic symbiosis. This association, which occurs at three late Silurian localities west of Parkes in central western New South Wales, involved the stromatoporoid both encrusting and eroding the coral skeleton. Although up to twelve percent of the corallite diameter is lost where erosion occurs, there does not appear to be any change in structure of the coral skeleton. Similarly, where encrusting occurs, the stromatoporoid-coral boundary is clearly marked by the presence of epithecal wall. Additionally, the stromatoporoid did not appear to have encrusted calices occupied by living polyps. All this suggests that only the skeleton below the living polyp was eroded or encrusted by the stromatoporoid. KERSHAW (1987, p.378) reported a similar association in which the stromatoporoid Clathrodictyon convictum enclosed the rugose coral Tryplasma flexuosum. Some of his specimens show the tops of corallites 1 to 3mm above the stromatoporoid surface. Apparently in both situations, the coral polyps were able to keep pace with growth of the stromatoporoid. In the Palaeozoic, stromatoporoids inhabited niches today occupied by other sponges. This association is analogous to modern sponge-scleractinian associations, in which encrusting sponges appear to use the skeleton as a substrate to elevate themselves above the sea floor. In turn the coral is protected from bioerosion by the coating of sponge tissue (GOREAU & HARTMANN 1966). The stromatoporoid-coral association is interpreted as a fossil example of this modern mutualistic association. The stromatoporoid did not completely enclose the coral and certainly used the coral skeleton as an elevating substrate to allow it to grow above the sea floor. Intermittent erosion of the coral skeleton probably had no deleterious effect. It occurred in parts which were already vacated by the polyp. Filling of the eroded space by stromatoporoid skeleton would have compensated for any loss of strength of the coral skeleton. No other bioeroders appear to have attacked the coral skeleton which would have been protected by the stromatoporoid. In the modern setting this association occurs in shallow environments with high sediment levels. It is also more common where coral numbers are high (AERTS & VAN SOEST 1997). A similar environment is inferred for the fossil association. Published with permission of the Director General, New South Wales Department of Mineral Resources. REFERENCES AERTS, L.A.M. & VAN SOEST, R.W.M., 1997. Quantification of sponge/coral interactions in a physically

stressed reef community, NE Colombia. Marine Ecology Progress Series, 148: 125-134.

GOREAU, T.F. & HARTMAN, T.D., 1966. Sponge: Effect on the Form of Reef Corals. Science, 151: 343-344. KERSHAW, S. 1987. Stromatoporoid-coral intergrowths in a Silurian biostrome. Lethaia, 20: 371-380.

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MIDDLE TO LATE ORDOVICIAN ACROTRETOID LINGULATE BRACHIOPODS FROM THE MOLONG VOLCANIC BELT, CENTRAL NSW MICHAEL ENGELBRETSEN Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Insoluble residues from acidised limestone samples collected from several localities in the Molong Volcanic Belt yielded a diverse Middle (Darriwilian) to Late (Eastonian) Ordovician acrotretoid brachiopod fauna consisting of twenty taxa: Hisingerella hetera PERCIVAL, 1978, Hisingerella sp. cf. H. sp. nov. A HOLMER, 1986, Hisingerella sp., "Conotreta" sp. cf. "C"mica GORYANSKI, 1969, "Conotreta" sp. cf. " C . " orbicularis HOLMER, 1986, "Conotreta" sp. A HOLMER, 1989, "Conotreta" sp. B, "Conotreta" sp. C, "Conotreta" sp. D, Biernatia sp. cf. B. sp. nov. WRIGHT & MCCLEAN, 1991, Biernatia sp. A, Biernatinae gen. et sp. indet., Numericoma sp. cf. N. simplex HOLMER, 1989, Undiferina sp. cf. U. rugosa COOPER, 1956, Scaphelasma scutula POPOV et al., 1994, Spondylotreta sp., Eoconulus sp. cf. E. antelopensis KRAUSE & ROWELL, 1975, Ephippelasma sp. cf. E. minutum COOPER, 1956, Rhysotreta sp., and acrotretid gen. et sp. indet. During Ordovician times the Molong Volcanic Belt (MVB), incorporated in the Lachlan Orogen of central NSW, formed a positive volcanic tectonic feature consisting of a cluster of semi-emergent offshore islands separated from the Gondwanan margin (Gnalta Shelf) to the west and by the Wagga Marginal Sea. This region lay in tropical climes where carbonate sediments were deposited in seas flanking the islands. Carbonate deposition occurred episodically, with three stratigraphically distinct limestones forming on the MVB from latest Middle Ordovician (Darriwilian) to middle Late Ordovician (Eastonian). The eastern margin of the MVB was displaced into deeper water where predominantly clastic deposition occurred along with occasional allochthonous limestones being derived from the western side of the MVB, on which carbonate sediments continued accumulating. Samples yielding acrotretoid faunas were collected from the northern MVB: the Oakdale Formation (predominantly Eastonian age), the Wahringa Limestone Member (late Darriwilian-early Gisbornian age), the Reedy Creek Limestone (early Eastonian age), and olistoliths in the Late Silurian Barnby Hills Shale (mid Eastonian age); west flank of the MVB: the Downderry Limestone Member (late Eastonian age); east flank of the southern MVB: the Malongulli Formation (early Bolindian age). Virtually all acrotretoid brachiopods documented were obtained from allochthonous limestones transported from outer shelf edge and periplatform deposits down the island slopes as isolated blocks or channel deposits. Acrotretoids living around the volcanic islands comprising the MVB mainly inhabited relatively deeper water environments (Benthic Assemblages 4-5), rather than shallow near-shore settings. Diminutive acrotretoid brachiopods confined to periplatformal sponge-dominated carbonates accumulating below the photic zone in water depths greater than 90m may have lived epifaunally on the sponges, suspended above the seafloor and capturing particulate matter entrained in currents set up by their hosts (PERCIVAL et al. 1999). This abstract is a contribution to IGCP410 "The Great Ordovician Biodiversification Event" REFERENCES PERCIVAL, I.G., ENGELBRETSEN, M.J., & BROCK, G.A. 1999. Distribution of Middle to Late Ordovician

lingulate brachiopods in New South Wales. Acta Universitatis Carolinae-Geologica, 43(1/2): 347-350.

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GIANT BIVALVES FROM THE SILURIAN MOLONG LIMESTONE, CENTRAL WESTERN NSW MICHAEL ENGELBRETSEN , JOHN FARRELL , DAVID MATHIESON , and JOHN PICKETT Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Specialist Services Section, Geological Survey of New South Wales, PO Box 76, Lidcombe NSW 2141, Australia The Molong Limestone (Wenlock-Ludlow) comprises the western and major belt of limestone within the Lachlan Fold Belt originally described from near the township of Molong by CARNE & JONES (1919, pp 170-171) and later redefined by ADRIAN (1971); the unit is 2.4km in width at Molong and extends for a distance of 5.6km north-northwest and at least 14km, with lenses of equivalent limestone having been mapped within the Panuara Formation some 16km, south of the township (ADRIAN 1971). The unit is mainly massive or thickly bedded, recrystallised, relatively unfossiliferous limestone interspersed with local occurrences of crinoidal or stromatoporoidal limestone containing rich fossil assemblages including, at least at one horizon, an abundance of "giant" bivalves (ADRIAN 1971, PICKETT 1982). 1

The "giant" or megalodont bivalves discussed herein are locally abundant along a limestone bed of strike length 333m and averaging 0.8m in thickness; preservation is poor with partial silicification in some specimens but with most being highly recrystallised as is commonly the case (COOK 1995) and thus precludes any definite taxonomic assignment, even at generic level. The associated faunal elements include brachiopods, gastropods, favositid corals, stromatoporoids, crinoidal debris and encrusting algae. The bivalve bed is directly overlain by a rhyolitic tuff layer several metres in thickness which has been SHRIMP dated, by use of zircons, as being 414.2+ 8.2Ma (PICKETT, pers. comm 1996); conodont data from Pickett's Foys Creek section (pers. comm 1996) through which the bivalve bed strikes, that is, the co-occurrence of Polygnathoides siluricus and Ancoradella ploeckensis some 250m stratigraphically above the tuff layer would indicate the bed is no younger than the early part of the siluricus Zone (middle Ludlow) and is most likely early Ludlow in age. The abstract represents a preliminary study and is a contribution to IGCP421 (North Gondwanan Mid-Palaeozoic Bioevent/Biogeography Patterns in Relation to Crustal Dynamics). REFERENCES ADRIAN, J. 1971. Stratigraphic units in the Molong District, New South Wales. New South Wales Geological

Survey - Records, 13(4): 174-198.

CARNE, J.E. & JONES, LJ. 1919. The Limestone Deposits of New South Wales. New South Wales Geological

Survey - Mineral Resources, 25. Xii + 411 pp.

COOK, A.G. 1995. A new Silurian megalodont bivalve genus from Bungonia, New South Wales. Memoirs of the

Queensland Museum, 38(2): 437-440.

PICKETT, J.W. 1982. The Silurian System in New South Wales. New South Wales Geological Survey - Bulletin,

29: 1-264.

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REWORKED SILURIAN CATOMBAL GROUP

AND ORDOVICIAN

CONODONTS WITHIN THE LATE

DEVONIAN

J O H N R. F A R R E L L

Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia The Catombal Group - Black Rock Sub-Group comprises, in sequence from youngest to oldest, the Macquarie Park Sandstone, Brymedura Sandstone and Paling Yard Formation. The prominent ridges in The Gap area are formed from Macquarie Park and Brymedura Sandstone that are more resistant to weathering than the underlying Paling Yard Formation. This latter formation is generally a recessive unit that in most areas is covered by hillwash or soil cover. However, in one locality on the eastern limb of a syncline it is exposed in a small gully (Section CWSS). This exposure consists predominantly of red and brown shale with several calc-lithite interbeds that vary in thickness from one to five metres and contain granule-sized fragments of re-worked limestone, beta quartz crystals and quartz pebbles. Many granules within these beds have styolitic boundaries and show recrystalization with cherty replacement (P. CONAGHAN pers. comm.). Samples processed for conodonts have produced a small selection of inarticulate brachiopods, crinoidal fragments, ostracods, gastropods and Onychodont teeth - the last being of Late Devonian origin (R. PARKES pers. comm.). Conodonts extracted are robust, fragmented and are contained within the limestone granules. They include the Silurian zonal species: Distomodus staurognathoides and Pterospathodus amorphognathoides plus: Kockelella cf. amsdeni and Pterospathodus procerus. Pseudobelodina sp., Yaoxianognathus? sp. and Phragmodus sp. were also recovered. These species have been recorded elsewhere in mid to late Ordovician strata. The re-worked nature of the limestone granules and their setting within a Late Devonian matrix accounts for the disparity of ages indicated by the conodont and fish data.

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PALEOGEOGRAPHY OF ORDOVICIAN GASTROPODS - A PRELIMINARY ANALYSIS JIRI FRYDA1, and DAVID M. ROHR2 1 2

Czech Geological Survey, Klirov 3/131,118 21 Praha 1, Czech Republic, frvda@cgu.cz Sul Ross State University, Alpine, Texas 79832, USA, drohr@sulross.edu

Despite of a relatively high gastropod biodiversity in many Ordovician benthic communities few studies have focused on their global paleogeography (ROHR 1 9 7 9 ; ROHR & BLODGETT 1 9 9 4 , 1 9 9 6 ; GUBANOV & ROHR 1 9 9 5 ; PERCIVAL 1 9 9 5 ; HORNY 1 9 9 7 ; FRYDA AND ROHR 1 9 9 9 ) . Poor knowledge of the Ordovician gastropod faunas from many areas (Siberia, Ibero-Armorica, China, etc.) as well as of their exact stratigraphic ranges has considerably complicated a detailed paleogeographic analysis. In addition, the gastropod faunas from some relatively well-known areas (Laurentia, Avalonia) have not been revised for many decades. We present preliminary results of paleogeographic analysis based on the geographic distributions of 52 Ordovician gastropod genera. The data, based on more than 2 5 0 0 species occurrences, were analyzed using clustering algorithms (UPGMA, WPGMA, and single linkage). Despite limited genera, our analyses suggest a utility of the Ordovician gastropods as paleogeographic indicators. Paleogeographic analysis of all known Ordovician gastropods has been prepared as part of the IGCP 410. Some preliminary results are noted bellow: 1. Geographic distributions of the Ordovician gastropods are roughly consistent with generally accepted paleogeographic models (MCKERROW & SCOTESE 1 9 9 0 ) . Peri-equatorial gastropod faunas are characterized by number of distinctive genera (Maclurites, Maclurina, Helicotoma, Ecculiomphalus, Trochonema, Teiichispira, Subulites, Hormotoma, Cyclonema, Ophileta etc.). On the other hand, southern high latitude gastropod faunas (Mediterranean province - NW Gondwana and peri-Gondwanan microplates) may be also characterized by a presence of endemitic gastropod genera (Carcassonnella, Thoralispira, Nonorios, Bucanopsina, etc). 2. Nature of the gastropod faunas from the Avalonia and Baltic-Russian platform suggests that during the Ordovician, the both represented areas of boundary mixing between the peri-equatorial and Mediterranean faunal types. This fact is fully consistent with their presumed paleogeographic positions. 3. Gastropod faunas of Perunica (Bohemia), in contrast to NW Gondwana and Ibero-Armorica, have a relatively high affinity to that of Baltica during the entire Ordovician. This fact testifies for the model of HAVLICEK et al. ( 1 9 9 4 ) suggesting a distinctive evolution of its benthic communities. The presence of onychochiloidean gastropods in the Ordovician rocks of Perunica (FRYDA & ROHR 1 9 9 9 ) and their absence in another areas of the Mediterranean province (NW Gondwana and Ibero-Armorica) represent the most important difference of Perunica. This fact together with pattern of the world-wide distribution of onychochiloidean gastropods has indicated a much northern position of Perunica. 4. Whiterockian gastropod faunas of the carbonate belt peripheral to the trans-equatorial Ordovician North American continent (Newfoundland, Nevada, British Columbia and part of Alaska), contain characteristic gastropod taxa (Palliseria, Monitorella, Malayaspira, Straparollina, Rossospira and Helicotoma). This distribution is consistent with Toquima-Table Head Biogeographic Province (ROSS & INGHAM 1 9 7 0 , NEUMAN & HARPER 1 9 9 2 ) .

REFERENCES J. & ROHR, D.M. 1999. Taxonomy and Paleobiogeography of the Ordovician Clisospiridae and Onychochilidae (Mollusca). Acta Universitatis Carolinae, Geologica, Geologica, 4 3 : 4 0 5 - 4 0 8 .

FRYDA,

GUBANOV, A.P. & ROI IR, D.M. 1995. Paleogeography of the Macluritidae (Ordovician-Gastropoda). Ordovician

Odyssey: Short papers for the 7th Interational Symposium on the Ordovician System, 4 6 1 - 4 6 4 . HAVLI'CEK V . , VANEK J. & FATKA O. 1 9 9 4 . Perunica microcontinent in the Ordovician (its position within the

Mediterranean Province, series division, benthic and pelagic associations). Sbornik UUG, Geologie, 46: 2356.

R. B. & HARPER, D.A.T. 1992. Paleogeographic significance of Arenig-Llanvirn Toquima-Table Head and Celtic brachiopod assemblages. In: B.D.Webby and J. Laurie, (eds.), Global perspectives on Ordovician geology, Balkema, Rotterdam.

NEWMAN,

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Ordovician gastropods of New South Wales: ecologic and biogeographic relationships. Ordovician Odyssey: Short papers for the 7th Interational Symposium on the Ordovician System, 453-456.

PERCIVAL, I . G . 1 9 9 5 .

ROHR, D.M. 1979. Geographic distribution of the Ordovician gastropod Maclurites. In: J. Gray and A.J. Boucot (eds.), Historical biogeography, plate tectonics, and the changing environment. Proceedings of the Annual Biology Colloquium and Selected Papers, 37:45-52. ROHR, D. M., BLODGETT, R. B.& FURNISH, W. M. 1992. Maclurina manitobensis (Whiteaves) (Ordovician

Gastropoda); the largest known Paleozoic gastropod. Journal of Paleontology, 66: 880-884. ROHR, D. M. & BLODGETT, R. B. 1994. Palliseria (Middle Ordovician Gastropoda) from east-central alaska and

its stratigraphic and biogeographic significance. Journal of Paleontology, 68: 674-675. Ross, R. J., JR. & INGHAM, J.K. 1970. Distribution of the Toquima-Table Head (Middle Ordovician Whiterock) faunal realm in the Northern Hemisphere. Geological Society ofAmerica Bulletin, 81:393-408. SCOTESE, C. R. & MCKERROW, W. S. 1990. Revised World maps. The Geological Society Memoir, 12:1-21.

157

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Pouters

MORPHOLOGICAL RESPONSE OF CONODONTS TO KELLWASSER ANOXIC EVENTS CATHERINE GIRARD and SABRINA RENAUD Laboratoire de Pateontologie, FRE 2158 CNRS UCB Lyon 1, F-69622 Villeurbanne Cedex, France Extinction and recovery periods are usually characterized by the description of community turn-over at a specific or generic level. However, such an approach is dependent on the adopted taxonomic concept, and does not involve the morphological variability of the palaeo-populatioijs. We therefore propose here an analysis of the morphological response of conodonts to successive Kellwasser anoxic events, at a population level, independent of taxonomic problems. For the genera Palmatolepis and Icriodus, all individuals from each stratigraphic level were pooled together independently of their size and their possible taxonomic determination. An outline analysis was performed on these samples, in order to determine the morphological characteristics of these palaeo-populations. This method allowed us to address several questions about the morphological evolution of conodonts during the Kellwasser period: - comparison of the response to successive anoxic events: Lower Kellwasser vs. Upper Kellwasser, - influence of the environment of deposition by comparison of shallower and deeper water deposits in the same area (Montagne Noire): Coumiac vs. La Serre, - influence of the geographic distance in similar environments: Coumiac (Montagne Noire) vs. M'rirt (Morocco). From these comparative studies, common patterns emerge, especially a morphological shift of Palmatolepis after the anoxic events, the response being stronger after the main event (Upper Kellwasser). Patterns of size evolution appear to be more complicated, possibly due to environmental effects.

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RECOVERY OF LATE DEVONIAN (FRASNIAN) MICROVERTEBRATES AND CONODONTS FROM THE CHAHRISEH AREA, NORTH EAST OF ESFAHAN, IRAN HOSSEIN GHOLAMALIAN1, SUSAN TURNER2, CAROLE J BURROW2 and MEHDIYAZDI1 1 2

Department of Geology, University of Esfahan, Iran Queensland Museum, PO Box 3300, South Brisbane Queensland 4101 and Department of Zoology and Entomology, University of Queensland, St Lucia Queensland 4072, Australia, s.turner@mailbox.uq.edu.au

A considerable number of fish scales associated with conodont species were recovered from the base of the Chahriseh section, north-east of Esfahan. According to the age determination of conodont and microvertebrate taxa, the horizons hi a, hi and Gi4 from the base of this section, in a unit which is equivalent to the lower part of the Shishtu Formation, can be dated as early Frasnian (middle falsiovalus Zone to hassi Zone). Some of the recovered conodont species from the Chahriseh section are Icriodus symmetricus, lcriodus subterminus and Icriodus expansus. One incomplete doubtful element of IBippenathus sp. cf. Bippenathus bippinathus has been found. Within the fish remains are a large number of well-preserved thelodont scales of Turinia hutkensis and Australolepis seddoni. Devonian turiniids are useful as worldwide keys for high-resolution biostratigraphy (TURNER 1 9 9 7 ) . Rare acanthodian scales are tentatively assigned to Nostolepis gaujensis VALIUKEVICIUS 1 9 9 8 , being comparable with the type material from the Svedasai-252 core (Frasnian, Sventoji Formation), Lithuania. Turinia hutkensis BLIECK & GOUJET 1 9 7 8 , was originally reported from an isolated block in Kerman, Iran pers. comm. 1 9 9 9 ) . The thelodont scales assignable to this species were recovered in situ in the Chahriseh area, so we propose that the Chahriseh area is a better type locality for this taxon. Australolepis seddoni TURNER AND DRING 1 9 8 1 , also known from the Gneudna Formation of Western Australia and Shotori Range of Iran (TURNER 1 9 9 7 , YAZDI & TURNER 2 0 0 0 in press, TRINAJSTIC, pers. comm. 1 9 9 9 ) , can be confirmed as a zone fossil for the Early Frasnian. This new data from the Chahriseh section can be used to aid worldwide biostratigraphic correlation in the future.

(JANVIER,

REFERENCES TURNER, S.

1997. Sequence of Devonian thelodont scale assemblages in East Gondwana. In G. Klapper, M, Murphy and J. Talent. Palaeozoic sequence stratigraphy, biostratigraphy and biogeography. Geological Society of American Special paper 321: 295-315, Colorado.

VALIUKEVICIUS, J. 1998. Acanthodians and zonal stratigraphy of Lower and Middle Devonian in East Baltic and

Byelorussia. Palaeontographica A, 248 (1-2): 1-53. YAZDI, M . & TURNER, S. 2 0 0 0

in press. Late Devonian and Carboniferous vertebrates from the Shishtu and Sardar Formations of the Shotori Range Iran. IGCP 421 meeting volume. Records of the Western Australian Museum.

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LATE PERMIAN (KAZANIAN) OSTRACODS, AND ASSOCIATED PALYNOMORPHS, FROM THE PETREL SUBBASIN, NORTHWESTERN AUSTRALIA P.J JONES and C.B. FOSTER 1

Department of Geology, The Australian National University, Canberra, A.C.T. 0200, Australia Australian Geological Survey Organisation, Canberra, A.C.T. 2601, Australia A small ostracod fauna is described from cuttings (480-510 m) in the Pearce Member of the Hyland Bay Formation penetrated by Barnett No. 1. It contains marine species Graphiadactyllis formosa SCHNEIDER 1966, first described from, and confined to, the Late Permian (Kazanian) of the Russian Platform. Amphissites sp. recorded here, shows affinities with Amphissites tscherdynzevi SCHNEIDER 1948, also illustrated from the Russian Platform. A new drepanellid (judahellid) genus, and two species of Healdia are also described. This Late Permian (Kazanian) assemblage is associated with palynomorphs of the Dulhuntyispora parvithola Zone, an association which repeats the nexus between this spore-pollen zone and the foraminiferal assemblage in the Bowen Basin, correlated with the Kazanian. 1

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Posters

SEA LEVEL CHANGES WITH REFERENCE TO CONODONT BIOFACIES IN THE FRASNIAN TO FAMENNIAN AT THE COL DES TRIBES (MONT PEYROUX) AND TOURRIER (CABRRIERES), MONTAGNE NOIRE, SOUTHERN FRANCE. FAZLI RABBI KHAN National Centre of Excellence in Geology, University of Peshawar, Pakistan Globally important Devonian-Early Carboniferous (Givetian-Tournaisian) sections outcrop in the Montagne Noire west of Montpellier, southern France. Two sections have been studied for conodont data through the Frasnian-Famennian boundary to obtain improved information on biofacies through time and sea level changes, modeled on the work of ZLEGLER (1979), SANDBERG& DREESEN (1984a, 1984b) and SANDBERGet al. (1988): 1) Col des Tribes, 750 m north of Mont Peyroux 2) Touri&re 1500 m west of Cabrrteres Transgressive and regressive phases are clearly expressed. At Mont Peyroux, pelagic deep sea facies are succeeded upwards by shallower, subtidal facies, reverting to deep sea pelagic facies at the top of the sequence. At Cabrrteres, deep-sea pelagic facies passes upwards into subtidal facies at the top of the section. REFERENCES ZlEGLER, W. 1979. Historical subdivision of the Devonian. In: M.R. House et al. (eds). The Devonian System,

Special Papers in Palaeontology, 23: 23-47. W. & SANDBERG, C.A. 1984a. Palmatolepis-bascd revision of upper part of the standard Late Devonian zonation. In D.L. Clark (ed.), Conodont biofacies and provincialism. Geological Society of America Special Paper, 196: 179-194.

ZlEGLER,

SANDBERG, C.A. & DREESEN, R. 1984b. Late Devonian icriodontid biofacies models and alternate shallow water conodont zonation. In D.L. Clark (ed.), Conodont biofacies and provincialism. Geological Society of America Special Paper, 196: 143-178.

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A POSSIBLE HYDROID FROM THE BOHEMIAN ORDOVJCIAN PETR KRAFT1 and JAROSLAV KRAFT2 1

The first discovery of the fossil taxon studied from the Klabava Formation (Arenigian of the Prague Basin) was published by BOUCEK (1956) under the designation Thamnograptus (?) rokycanensis. More than 30 specimens have been found since this time. They come from the Klabava, Sarka and Dobrotivd formations (ArenigianDobrotivian). Their planar, feather-like colonies are composed of the main branch giving rise to alternating thin lateral branches. Only three specimens from the studied material are branched. Two extraordinarily preserved specimens display fine morphological features of thin lateral branches. The shape and the very high density of "thecae" resemble hydroid rather than graptolithic architecture. The branching of colonies and the variable density of lateral branches permit us to make some palaeoecological interpretations based on actualistic correlation with recent hydroids (Fig.l).

All specimens come from the Klabava Formation. All drawings are on the same scale; scale bar - 10 mm. REFERENCES 1956. Graptolitova a dendroidova fauna klabavskych bridlic z rokycanske Strane. Sbor. Ustr. Ust. geol., Odd. paleont., 22, 123-227.

BOUCEK, B.

RLEDL, R. 1971. Water movement. Animals. - In: O. Kinne (ed./- Marine ecology. Vol. I. Environmental factors,

part 2. John Wiley & Sons Ltd., Wiley-Interscience, London, New York, Sydney, Toronto, pp. 1123-1156.

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GROWTH CHARACTERISTICS IN SOME EARLY TABULATES (LATE ORDOVICIAN; MANITOBA, CANADA), AND THEIR PALEOBIOLOGY AND PHYLOGENETIC IMPLICATIONS DONG-JIN LEE1 and ROBERT J. ELIAS2 1

Department of Earth and Environmental Sciences, Andong National University, Andong 760-749, Seoul, Korea Department of Geological Sciences, University of Manitoba, Winnipeg, R3T 2N2, Canada

Growth characteristics in the early tabulate coral genera Saffordophyllum, Trabeculites, Manipora, and Catenipora are documented from the Late Ordovician (middle Maysvillian to early Richmondian) of southern Manitoba, CanadaSaffordophyllum and Trabecules formed cerioid coralla, whereas Manipora and Catenipora produced cateniform coralla. These early tabulates exhibit an unprecedented range in types of increase known from both cnidarians and poriferans. In addition to lateral increase, typical in tabulates and compatible with cnidarian biology, axial increase resembling that in some poriferans also occurred in these taxa. Axial increase could take place during rejuvenation or regeneration following injury or death of polyps, as recorded by entry of sediment into corallites. In most cases, however, the absence of such sediment suggests that axial increase was also a normal mode of increase. Peripheral expansion, a normal mode of increase in certain poriferans, possibly occurred during recovery from damage and partial mortality in Saffordophyllum and Trabeculites. In addition to the various types of increase, other growth characteristics including recovery from damage and partial mortality, and corallite fusion and decrease are also peculiar in these corals. The capacity for recovery demonstrates a high degree of efficiency. Rapid regeneration commonly involved axial increase in all genera. Small lacunae with circular or lenticular cross-sections that formed during recovery became sites of rapid lateral increase or corallite decrease in the cerioid forms. Various lines of evidence indicate that the level of colony integration in these genera was probably higher than previously assessed. Corallite fusion and decrease in Saffordophyllum and Trabeculites indicate that substantial soft-tissue connection among polyps was possible. Development of new corallites in Manipora commonly involved two to four polyps, suggesting a high degree of coordinated behavior and function among polyps, and perhaps astogenetic control over colony development. In Saffordophyllum, a cateniform early stage is remarkably similar in general appearance to Manipora and Catenipora. The recent discovery of agglutinated patches with polygonal corallites in some Catenipora coralla is also of particular interest for further study on the phylogenetic relationship or homeomorphy of these corals. Growth characteristics of these early tabulates are very different from those of typical tabulates. The discovery of unique abilities and unprecedented range in types of increase demonstrates the critical need for detailed palaeobiologic studies, especially on early Paleozoic forms from elsewhere. This is essential if we are to understand the early evolutionary history of corals and to establish reliable criteria for the recognition of taxonomic groups and for the distinction of tabulate corals and their homeomorphs.

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INVESTIGATION OF CONODONTS COLOUR ALTERATION INDEX FROM THE BOOTH LIMESTONE SOUTH OF COBAR, NEW SOUTH WALES, AUSTRALIA DAVID K. MATHIESON Center for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Science, Macquarie University, NSW 2109, Australia The Booth Limestone Member outcrops 80 km south of Cobar on "Lachlan Downs" as part of the Devonian Winduck Group and Cobar Subgroup. ( MAC RAE 1989) Samples of the Booth Limestone collected by Prof Evan Leitch (University of Technology Sydney), were acid leached in order to obtain a conodont age for the deposit. The conodonts indicate an Early Devonian age, close to the Lochkovian-Pragian boundary (pesavis Zone or more likely sulcatus Zone) MAWSON pers. comm. The conodonts recovered from the Booth Limestone Member have a significantly lower Colour Alteration Index (CAI of EPSTEIN et al. 1977)than broadly synchronous elements from carbonate sequence in the eastern Lachlan Fold Belt. This may have implications for thermal heat flow and hydrocarbon prospectivity. REFERENCES A.G., EPSTEIN J.B., & HARRIS, L.D., 1977. Conodont colour alteration-An index to organic metamorphism: U.S. Geol. Surv. Prof. Pap. 9 9 5 , 2 7 p., 2 0 text-fig.

EPSTEIN,

MACRAE, G.P., 1989. Geology of the Lachlan Downs 1:100,000 Sheet 8033. New South Wales Geological

Survey, Sydney.

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SILICIFIED EARLY DEVONIAN (LOCHKOVIAN) GASTROPODS FROM WINDELLAMA, SOUTHEASTERN AUSTRALIA RUTH MAWSON and DONALD SMITH Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Gastropods are documented from three developments of silicification within the Early Devonian (Lochkovian; eurekaensis and delta zones) Windellama Limestone of south-eastern Australia. As few gastropods have been previously documented from Lochkovian limestone horizons in Australia, it is not surprising that the Windellama fauna, consisting of more than 800 individuals, contains a number of new forms. New taxa include one new genus and species of murchisoniacean and new species of 6 genera: Ruedemannia, Gyronema, "Cyclonema" Himantonia, Murchisonia, and Subulites (Fusispira). Additionally, a new unnamed gastropod genus and an unnamed new species of Straparollus (Euomophalus) have been recognised.

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CARBON ISOTOPE STRATIGRAPHY OF THE MID-ASHGILL (LATE ORDOVICIAN) TO LOWER TELYCHIAN (EARLY SILURIAN) OF THE CAPE PHILLIPS FORMATION, CENTRAL CANADIAN ARCTIC ISLANDS M.J. MELCHIN and C. HOLMDEN 1

Department of Geology, St. Francis Xavier University, Antigonish, Nova Scottia, B2G 2W5, Canada, mmelchin@stfx.ca Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada, chris.holmden@usask.ca

Samples were collected for analysis of carbon isotopes from the organic matter and carbonate fractions of the Cape Phillips Formation on Cornwallis and Truro islands in Arctic Canada. The 8 C signal through the Ashgill part of the section closely resembles the pattern seen at Dob's Linn, Scotland (UNDERWOOD et al 1997) and in South China (WANG et al. 1997): a relatively weak positive shift in the lower pacificus Zone, a strong positive shift in the early Hirnantian extraordinarius Zone, followed by a return to "background" values in the late Hirnantian persculptus Zone. The Cape Phillips record differs from the Dob's Linn results in two important respects. The magnitude of the positive shifts is greater in the Arctic samples. The maximum magnitude of the excursion (up to +9%o) occurs in a section that is proximal to the shallow shelf margin but varies across the basin. Dob's Linn, which is regarded as a distal slope or basinal succession, shows a Hirnantian excursion of +5%o. The Cape Phillips record also differs from that at Dob's Linn in that it shows more conspicuous evidence of a brief return to more negative values during the overall excursion interval, thus, the shape of the early Hirnantian excursion profile is characterized by a double-peak. A similar pattern was seen in South China. This may correspond with sedimentologic evidence for two distinct glacial events within the Hirnantian (BRENCHLEY & §TORCH 1989). The 5 C signal through the same interval in Cape Phillips Formation shows no strong positive shift through the early Hirnantian as seen in the 8 C . This contrasts with studied sections in carbonate shelf and slope successions elsewhere in Laurentia and in Baltica where the excursion is observed in the carbonates. We postulate that the reason for the lack of excursion in these 5 C b samples is that the carbonate sediments in this interval appear to be largely detrital, possibly derived from erosion of the adjacent carbonate shelf exposed during the early Hirnantian. l3

org

carb

org

car

The strong positive shift in the 5 C g signal seen in these sediments, as in many other parts of the world, corresponds with a period of glaciation and sea level fall, as well as a major extinction event. Changes in oceanic organic productivity and/or rate of organic matter burial, atmospheric C0 concentration, and rate and style of continental weathering have been suggested as possible explanations for the positive C-isotope shift. ,3

In the Llandovery succession, the 5 C g signal shows a series of overall oscillations, mostly over a range of variation of ±l-3%o. The timing of these oscillations show a striking degree of qualitative coincidence with the sea level changes in several published eustatic curves. Positive 8 C g shifts coincide with proposed times of low sea level (lower and upper Aeronian) and negative shifts with times of higher sea level (upper Rhuddanian, midAeronian and lower Telychian). The most striking of the positive shifts occurs in the upper Aeronian, sedgwickii Zone-equivalent strata. In addition to being a time of eustatic fall it has also been identified as a time of high extinction rates in the graptolites. Both the early and late Aeronian times of sea level fall have been correlated with episodes of glacial expansion in South America. If the C-isotope does represent a proxy for eustacy, it suggests that in the Rhuddanian, sea level reached its maximum in the upper persculptus-lov/cv acuminatus zones and generally fell through rest of the lower-mid-Rhuddanian. 13

REFERENCES BRENCHLEY, P. J. & STORCH, P. 1989. Environmental changes in the Hirnantian (Upper Ordovician) of the

Prague Basin, Czechoslovakia. Geological Journal, 24:165-181.

UNDERWOOD, C. J., CROWLEY, S.F., MARSHALL, J.D. & BRENCHLEY, P.J. 1997. High-resolution carbon isotope

stratigraphy of the basal Silurian stratotype (Dob's Linn, Scotland) and its global correlation. Journal of the

Geological Society of London, 154:709-718.

WANG, K., CHATTERTON, B.D.E. & WANG, Y. 1997. An organic carbon isotope record of the Late Ordovician to

Early Silurian marine sedimentary rocks, Yungtze Sea, South China; implications for C0 changes during the Hirnantian glaciation. Palaeogeography, Palaeoclimatology, Palaeoecology, 132:147-158. 2

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ACRITARCH AND PRASINOPHYTE ALGAE OF THE WENLOCK AND LUDLOW SERIES (SILURIAN) OF THE TYPE AREAS GARY L. MULLINS, RICHARD J. ALDRIDGE and DAVID J. SIVETER Department of Geology, University of Leicester, University Road, Leicester, LEI 7RH, United Kingdom The use of acritarchs and prasinophyte algae in high resolution biostratigraphy has long been suggested, although the full correlative potential of these groups has never been realized as their biology is poorly understood and their taxonomy is in many cases unresolved. Undoubtedly, analysis of these groups also has great potential in determining palaeoenvironmental fluctuations and they should prove critical in testing the climatic/oceanic models proposed for the Silurian (eg. JEPPSSON 1990, LOYDELL 1998). Further, it should be possible to use the substantial palynomorph database to test evolutionary models such as the Red Queen hypothesis (VAN VALEN 1973) and the turnover hypothesis (VRBA 1993). Our new project on the acritarchs and prasinophyte algae of the type areas of the Wenlock and Ludlow series (Welsh Borderland, UK) aims to address these problems. Additional data and expertise is being provided by R. E. Elliott, J. Washington-Evans, P. Swire, K. Doming (Sheffield), S. G. Molyneux (British Geological Survey) and A. Le Heriss6 (Universite de Bretagne). Refined acritarch and prasinophyte biostratigraphical schemes have already been proposed for the lower Ludlow (MULLINS in press). Based on UK sequences, research has already begun to provide a detailed insight of middle Silurian palaeoenvironmental fluctuations and further analysis will enhance our understanding of the taxonomy and biology of Silurian acritarchs and prasinophyte algae. REFERENCES JEPPSSON, L. 1990. An oceanic model for lithological and faunal changes, tested on the Silurian record. Journal

of the Geological Society, London, 147: 663-674. LOYDELL, D. K. 1999. Early Silurian sea-level changes. Geological Magazine, 135: 4 4 7 - 4 7 1 . MULLINS, G. L. in press. Acritarchs and prasinophyte algae from the Elton Group, Ludlow Series, of the type

Ludlow area. Monograph of the Palaeontographical Society. VAN VALEN, L. 1973. A new evolutionary law. Evolutionary Theory, 1: 1-30. VRBA, E. 1993. Turnover-pulses, the Red Queen, and related topics. American Journal of Science, 293A: 418-

452.

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A COMPOSITE SILURIAN RADIOLARIAN BIOZONATION FOR NORTH AMERICA AND EURASIA P.J. NOBLE Department of Geological Sciences, University of Nevada, Reno NV 89557-0138, USA Recent advancements in Silurian radiolarian studies allow for the construction of a preliminary biozonation composed of 4 broad faunal zones and distinct assemblages within. A hybrid scheme is used that combines the FAD/LADs for short-ranging genera and species, the FAD/LADs of longer ranging morphotypes, and faunal associations. This scheme allows the assignment of samples to broad faunal zones, or in some cases, specific assemblages recognized within these zones. This zonation is very useful in assigning ages to siliceous strata that commonly contain little else besides radiolarians. RANGES OF SELECTED GENERA & SPECIES GROUPS

SYSTEM/SERIES/ STAGE

ASSEMBLAGES

Pridoi

1 ? 1

Ludlow

ZONES NOBLE &AITCHISON, NAZAROV, 1988 2000

Devoniglansus Pseudospongoprurum S. magnispina Praespongocoelia

Fbst-rotasphadr Zone

Long-Spined Inaniguttid

lnanihella tarangulc Secuicollacta cas: a

Zone 3 1 -

W enlock

Long-Spined Inaniguttid Zone 2

ii i

Haplotaeniatum tegimentum

Pylomate/ Igoncerfe sphaerelian Zone 2

Llandovery 1

i i

PYLOMATE - LARGE CONCENTRIC SPHAERELLARIAN ZONE 2 This zone is characterized by large concentric spongy or labyrinthine radiolarians, some of which are pylomate. Secuicollacta is also a common component. This zone is roughly equivalent to the H. tegmentum assemblage of NAZAROV, 1988 and occurs in Nevada, the Urals, Thuringia, Sweden, and the Canadian Arctic. The base is tentatively placed at the base of the Llandovery, although the oldest calibrated samples correlate to the late Rhuddanian M cyphus graptolite zone. The youngest known occurrence is middle Telychian (S. turriculatus graptolite Zone). LONG-SPINED INANIGUTTID ZONE 2 This is an interval zone whose base is defined by the LAD of Haplotaeniatum and the top is defined by the FADs of Ceratoikiscum and lnanihella tarangulica group taxa. This zone is recognized in the latest Llandovery middle Wenlock of the Canadian Arctic, and possibly in the Wenlock of Britain. The age assignment is based on graptolites, with the oldest samples assignable to the latest Llandovery (C. sakmaricus zone) and the youngest to the middle Wenlock (C. rigidus graptolite zone). LONG-SPINED INANIGUTTID ZONE 3 This zone is characterized by a predominance of the Inanhiella tarangulica group and related morphotypes. The base is defined by the FAD of Ceratoikiscum and the top by the LAD of the rotasphaerids. Several distinctive, geographically widespread assemblages occur within this zone. This zone is roughly equivalent to Nazarov's lnanihella tarangulica - Secuicollacta cassa assemblage. It has thus far been recognized in the Urals, the Canadian Arctic, Japan, west Texas, and Australia. Age assignment is based on a sample from the Urals that straddles the Wenlock - Ludlow boundary and on a sequence of samples from the Canadian Arctic.

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POST-ROTASPHAERID ZONE This is an interval zone whose base is the LAD of the rotasphaerids, and the top is related to the last abundant inaniguttids. The Devoniglansus-Pseudospongoprunum assemblage, which is recognized in Japan, west Texas, and Nevada, occurs within this zone. This zone has thus far been recognized in Japan, west Texas, and Nevada. All localities are from chert successions with little independent age control. Conodont data show the base to be no older than early Ludlow and the top to be no younger than late Pridoli.

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A LATE SILURIAN ACANTHODIAN FROM COEVAL CARBONATES IN VICTORIA, NEW SOUTH WALES AND SOUTHERN CHINA ROSS PARKES1, ANDREW SIMPSON2 and JOHN FARRELL1 1

Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University NSW 2109, Australia

Division of Environmental and Life Sciences, Macquarie University NSW 2109, Australia

Vertebrate microremains of the acanthodian Poracanthodes qujingensis WANG N-Z & DONG Z-Z have been recovered in Australia from three Late Silurian locations : the Cowombat Formation in eastern Victoria, the Silverband Formation of the Grampians in western Victoria, and from an unnamed allochthonous limestone block near the Bell River east of The Gap, between Molong and Wellington, New South Wales. Conodont data indicate a Ludlow to Pridoli age for the Cowombat Formation (SIMPSON & TALENT 1995). Poracanthodes qujingensis was obtained from low in the unit where conodont faunas are dominated by longranging taxa such as Ozarkodina excavata excavata and Panderodus unicostatus. Approximately 100 m stratigraphically higher than the fish occurrence, a small number of the latest Ludlow to Pridoli index form Ozarkodina remscheidensis eosteinhornensis have been documented (SIMPSON & TALENT 1995). More significantly, a single occurrence of the Ludlow Coryssognathus dubius is recorded from above the fish horizon. Burrow (1997) identified P. qujingensis from the Silverband Formation. TURNER (1986) indicated the age of the Silverband Formation to be Late Silurian/Early Devonian, based on the faunal association of thelodontid agnathans, climatiid and ischnacanthid acanthodians, lingulids, and ostracodes. The unnamed limestone block in the central west of NSW yielding Poracanthodes qujingensis forms part of a series of strike aligned blocks adjacent to the Bell Fault east of The Gap, within the Barnby Hills Shale. On the basis of conodont faunas, the limestone block is believed to be approximately coeval with the Cowombat Formation occurrence. Poracanthodes qujingensis was previously reported (WANG N-Z & DONG Z-Z, 1989) from the Late Silurian crispa Zone Miaogao Formation of eastern Yunnan. Its presence in south-eastern Australia is consistent with other instances of Late Silurian Sino-Australian palaeogeographic similarities. REFERENCES BURROW, C.J., 1997. A poracanthodid acanthodian from the Silverband Formation, the Grampians, Victoria, and its palaeobiogeographical significance. Geological Society ofAustralia Abstracts 44:1-2. SIMPSON, A.J. & TALENT, J.A., 1995. Silurian conodonts from the headwaters of the Indi (upper Murray) and Buchan rivers, southeastern Australia, and their implications. Courier Forschungsinstitut Senckenberg 182: 79-215.

TURNER, S, 1986. Vertebrate fauna of the Silverband Formation, Grampians, western Victoria Proceedings of the Royal Society of Victoria 98: 53-62 WANG NIAN-ZHONG & DONG ZHI-ZHONG, 1989. Discovery of Late Silurian microfossils of agnatha and fishes from Yunnan, China. Acta Palaeontologica Sinica 28 (2): 193-206.

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ORDOVICIAN (BENDIGONIAN TO EASTONIAN) INVERTEBRATE FAUNAS FROM THE NORTHERN MOLONG VOLCANIC BELT OF CENTRAL NEW SOUTH WALES IAN G. PERCIVAL1, BARRY D. WEBBY2 and JOHN PICKETT1 1

Specialist Services Section, Geological Survey of New South Wales, PO Box 76, Lidcombe, NSW 2141, Australia Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia

Fossiliferous carbonate facies recently recognised during mapping of the northern Molong Volcanic Belt in central NSW, between Molong and Wellington, reveal a diversity of invertebrate faunas in strata older than the previously well-studied Late Ordovician horizons in the southern continuation of this belt. The oldest fauna in the region was obtained from allochthonous limestones in the lower part of the Hensleigh Siltstone, in the Bakers Swamp district 28 km south of Wellington. These limestones yield a sponge, lArchaeoscyphia, and indeterminate trilobite remains, together with a rich conodont assemblage (to be described elsewhere). The conodonts confirm the early Bendigonian age determined from graptolites in the upper part of the Hensleigh Siltstone. A stratigraphic gap approximately 15 Ma in duration separates the Hensleigh Siltstone from the Fairbridge Volcanics. In the lower part of this formation, the 88 m thick Wahringa Limestone Member contains a diverse shallow water fauna, dominated in basal beds by abundant sponges (3 genera), the gastropod Maclurites cf. M florentinensis, michelinoceratid nautiloids, and a new species of the early tabulate coral Billingsaria. Brachiopods (?Sowerbyites sp. nov., and a leptellininid) are prominent in the middle part of the Wahringa Limestone Member, while the stromatoporoids Labechia banksi and Labechiella regularis are present towards the top of the unit. Elements of the Wahringa Limestone Member assemblage are biogeographically significant in displaying similarities with contemporaneous Tasmanian faunas. Associated conodonts (described elsewhere) indicate a late Darriwilian to early Gisbornian age for the Wahringa Limestone Member. In the upper Fairbridge Volcanics, near Molong, another shallow water carbonate unit - the Yuranigh Limestone Member, of late Gisbornian age - yields a low diversity fauna. Species present show almost no similarity with those from the older Wahringa Limestone Member, and include the brachiopods IDinorthis, Ishimia, and Leptellina, together with murchisonid gastropods, trilobites, ostracodes, a Prasopora-like bryozoan, and a lithistid sponges referred to lAmplaspongia. The youngest horizon in the northern Molong Volcanic Belt from which an Ordovician shelly fauna is documented here, occurs in the Oakdale Formation west of Wellington. This assemblage, of late Eastonian age, includes a probable new genus of orthide brachiopod, and a halysitid coral resembling both Quepora and Halysites praecedens WEBBY & SEMENIUK. The presence of this coral confirms an age no older than Webby's coral/stromatoporoid Fauna III. Documentation of these shelly faunas for the first time enables correlation to be more rigorously established between these successions in the northern Molong Volcanic Belt and those in the Junee-Narromine Volcanic Belt to the west near Parkes, particularly for the previously poorly known pre-Eastonian assemblages. ['Published with permission of the Director General, NSW Department of Mineral Resources. This is a contribution to IGCP 410 "The Great Ordovician Biodiversification Event".]

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SUBSURFACE FACIES ANALYSIS OF THE MUCH WENLOCK LIMESTONE FORMATION (SILURIAN), ENGLAND DAVID C. RAY Department of Geology, University of Cincinnati, P.O. Box 210013, Cincinnati OH 45221-0013, USA, ravdc@email.uc.edu Detailed comparisons between geophysical logs and measured sections within the Much Wenlock Limestone Formation has allowed the correlation of depositional packages and in some cases individual beds within this carbonate sequence. The application of this technique in conjunction with the identification of key K-bentonite marker horizons, has greatly improved the overall stratigraphic resolution for this region, far beyond that allowed by biostratigraphy. The presence of eight traceable K-bentonites within the West Midlands, permits the highest attainable stratigraphic resolution, as the deposition of a single ash bed lasts at most a few weeks, such horizons, therefore, may be used as time-lines for regional geological and palaeontological studies. Within the northeastern part of the Midland Platform (West Midlands), nineteen distinct lithological packages can be determined within the Much Wenlock Limestone Formation (total thickness 50m), most of which can be correlated throughout the region. Based on such correlations lithologies can be traced perpendicular to the depositional strike, allowing the effect of differing water depths to be assessed in terms of a geophysical signature that is directly related to lithological change. Geophysical logs regionally show the Much Wenlock Limestone Formation maintaining the approximately equal thickness across the Midland Platform. Furthermore, logging of the Much Wenlock Limestone Formation, near the town of Dudley [SO 922 938], has permitted the development of a sea level curve that consists of an upper and lower sequence of shallow water carbonates and a deeper water core of nodular limestones and shales. The development of a high-resolution sea level curve and the identification of regionally continuous K-bentonites have the potential for the correlation of the Much Wenlock Limestone Formation with similar aged strata out side of the Midland Platform.

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AN UNUSUAL LATE ARENIG ASSEMBLAGE OF GRAPTOLITES, RHABDOPLEURAN HEMICHORDATES AND CHITINOUS HYDROIDS FROM THE BANESTAN AREA, EASTCENTRAL IRAN. R.B. RICKARDS1, M.A. HAMEDI2 and A.J. WRIGHT3 1 2 3

Department of Earth Sciences, University of Cambridge, England. Geological Survey of Iran, Tehran, Iran. School of Geosciences, University of Wollongong, Wollongong, NSW, Australia

A rich benthic and planktic graptolite fauna, associated with encrusting rhabdopleuran hemichordates and chitinous hydrozoans, occurs in the late Arenig part of the Katkoyeh Formation at Banestan, east-central Iran. This locality and fauna was probably discovered by Huckriede et al. (1961) who reported Didymograptus and "Dendrograptiden" from east of Assiab, where Banestan is located. The fauna occurs in fine clastics of the Katkoyeh Formation (RICKARDS et al. 1994) close above Cambrian dolomites; higher in this dominantly clastic sequence is a thin limestone which has yielded bryozoans described by Ross, HAMEDI & WRIGHT (in press) and shelly fossils discussed by BASSETT et al. (1999). Shelly fossils occur rarely with the graptolites, but include asaphid trilobite fragments and crinoid ossicles; numerous chitinozoans and rare scolecodonts are present. This work describes the full Banestan fauna, part of which was described by RICKARDS et al. (1994); all specieslevel taxa are described from Iran for the first time. The only other Iranian graptolites described are the Late Ordovician and Early Silurian faunas of southern Iran (RICKARDS et al. 2000). Dendroid graptolites from the fauna are Callograptus sp. nov., Dictyonema sp. nov., Dendrograptus sp. cf. D. flexuosus J. HALL, 1865; Acanthograptus divergens SKEVINGTON, 1963; and Thallograptus ?succulentus RUEDEMANN, 1904. Unusual elements are the tuboid graptolite Galeograptus sp., the rhabdopleuran hemichordates Rhabdopleura sp. aff. R. primaevus (KOZLOWSKI, 1967) and Kystodendron sp., and the chitinous hydroid Palaeotuba sp. Graptoloid graptolites in the fauna are: Aulograptusl sp., Didymograptus incertus PERNER, 1895; Undulograptus formosus (Mu & LEE, 1958); and Yutagraptus sp. cf. Y. mantuanus RLVA, 1993. The presence of Undulograptus, Didymograptus incertus and Yutagraptus sp. cf. Y. mantuanus clearly indicates a late Arenig (late Yapeenian to early Darriwilian) age. Two other recent studies have provided information on this sequence. REITZ & DAVOUDZADEH (1995) assigned a "Llandeilo to Caradoc" age to acritarchs from the Katkoyeh Formation at Banestan, and inferred a warm water palaeoenvironment. BASSETT et al. (1999) stated that there are some 60 m of "shales, siltstones and igneous interbeds" above the dolomites, eventually overlain by a thin limestone with a maximum age of Llandeilo. Some biostratigraphic uncertainty results from the unusual nature of our fauna. COOPER & LLNDHOLM (1990) concluded that the base of the Darriwilian stage is marked by the incoming of several diplograptid genera, and that subsequently Aulograptus appeared, followed by new faunas. In mid-to high latitudes, as was the location of the Iranian plate at this time (eg., COOPER, FORTEY & LINDHOLM 1991; MITCHELL & MALETZ 1995), pendent didymograptids appeared; in the low latitude Pacific (including eastern Australia) this was "replaced" by a dichograptid fauna including isograptids and sinograptids. Our Banestan fauna does include pendent didymograptids but no isograptids or sinograptids. More unusual elements are the rhabdopleurans and chitinous forms as well as abundant dendroids (which may, of course, have been largely overlooked in previous studies of faunas of this general age). The nature of our fauna adds to models such as that of COOPER et al. (1991) who discriminated several biotopes, including an "inshore biotope" to which our fauna must belong. Although there is no doubt that the Banestan Formation is complex in its variation including pillow lavas in the Katkoyeh section, shallow shelf limestones and fluvial sequences, in the Banestan section the graptolite fauna is in the sequence between Late Cambrian dolomites and the ?Llanvirn limestone. Taken together with the abundant rhabdopleurans and intact dendroid colonies, our fauna must have accumulated in a quiet relatively shallow shelf environment. So, in addition to the pelagic didymograptids, we also have a rich and distinctive benthic graptolite fauna lacking to all intents and purposes a benthic shelly fauna. The Banestan sequence does lend broad support to the concept of a transgressive event near the Yapeenian/Darriwilian Arenig-Llanvirn boundary.

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REFERENCES BASSETT, M . G . , DASTANPOUR, M . & POPOV, L. 1999. New data on Ordovician

fauna and stratigraphy of Kerman and Tabas regions, east-central Iran. Acta Universitatis Carolinae (Geological 4: 483-486.

COOPER, R . A . & LINDHOLM, K . 1990. A precise worldwide correlation of early Ordovician graptolite sequences.

Geological Magazine, 127: 4 9 7 - 5 2 5 . R.A., FORTEY, R.A. & LINDHOLM, K. 1991. Latitudinal and depth zonation of early Ordovician graptolites. Lethaia, 24: 199-218.

COOPER,

HUCKRIEDE, R, KORSTEN, M. & VENZLAFF, H. 1962. Zur Geologie des Gebietes zwischen Kerman und Sagand

(Iran). Beiheftezum Geologisches Jahrbuch, 51: 197 pp. MITCHELL, C.E. & MALETZ, J. 1995. Proposal for the adoption of the base of the Undulograptus austrodentatus

Biozone as a global stage and series boundary level. Lethaia, 28: 317-331. REITZ, E. & DAVOUDZADEH, M . 1995. Ordovician acritarchs from the Banestan, Kerman area, Central Iran:

paleobiogeographical evidence for a warm environment. Neues Jahrbuch fur Geologie und Paleontologie, Monatshefte, 1 9 9 5 / 8 : 4 8 8 - 5 0 0 . RICKARDS, R.B., HAMEDI, M.A. & WRIGHT, A.J. 1994. A new Arenig (Ordovician) graptolite fauna from the

Kerman district, east-central Iran. Geological Magazine, 131: 35-42. RICKARDS, R.B., HAMEDI, M . A . & WRIGHT, A.J. (in press). Late Ordovician and Early Silurian graptolites from

southern Iran. Records of the Western Australian Museum, Supplement, 58. Ross, J.R.P., HAMEDI, M . A . & WRIGHT, A.J. (in press). Ordovician bryozoans from east-central Iran. Smithsonian Contributions to Marine Sciences.

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A BRIEF HISTORY OF SILURIAN TIME USING CONODONTS ANDREW SIMPSON Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia, asimpson@els.mq.edu.au The quest for finer biochronologic subdivisions that can be applied globally has been the major focus for those working with Silurian conodont faunas. This study reviews the results of almost four decades work in this area and concludes that a high resolution biochronologic framework of global utility is emerging at least for some intervals within the Silurian Period. The first attempt at subdividing the Silurian with conodonts was undertaken by WALLISER (1962) who plotted the comparative ranges of 40 Silurian and Early Devonian forms. A more detailed scheme, published 2 years later (WALLISER 1964), was based on the Cellon section but incorporated data from other European localities. The scheme has proved widely applicable with some zones {celloni, amorphognathoides, ploeckensis and siluricus) identified globally and others of limited application away from the Carnic Alps. Many subsequent zonations have been local variations or modifications of the Cellon zonation (ALDRIDGE 1972 - WELSH BORDERLAND, NICOLL & REXROAD 1969 - Brassfield Formation, LINK & DRUCE 1972 - Yass Basin, KLAPPER & MURPHY 1975 - Roberts Mountain Formation, BARRICK & KLAPPER 1976 - Clarita Formation, ZHOU et al 1981 - Guizhou Province, VIIRA 1982 - shelf and basin Baltic sequences, BLSCHOFF 1986 - central western New South Wales, CORRADLNL & SERPAGLI 1999 - Sardinia). These various schemes have consisted of first appearance zones, taxon range zones, lineage zones and informal assemblage zones, or a mixture thereof. COOPER (1980) introduced the data plane concept and nominated two horizons equating with the closure of the amorphognathoides and siluricus zones as being of global correlative value. KLEFFNER (1989) first applied the

graphic correlation technique to Silurian conodont faunas. In recent times there has been a growing awareness of patterns of cyclicity in Silurian marine sequences (ALDRIDGE et al. 1993) and the identification of a number of distinctive isotopic signatures (TALENT et al. 1993)

that can be correlated with times of high faunal turnover. Studies of large conodont populations reveal a number of datum planes within these events that permit a biochronologic resolution that is of a higher order of magnitude than earlier studies (JEPPSSON 1997). These events typically coincide with the closure of intervals characterised by diverse faunas with many platform-equipped Pa elements. High grade resolution within these time periods is also possible through the study of large populations (MANNIK 1998). To date, most advances have been made within, and at the close of, the celloni-amorphognathoides interval. It is, therefore, most likely that there is great potential for further subdivision of the ploeckensis-siluricus interval through the detailed study of large populations. An amalgamation of large population studies of conodonts with isotopic data and data from other faunal and floral groups will probably provide the next generation of insights into Silurian biochronology. REFERENCES ALDRIDGE, R.J. 1972. Llandovery conodonts from the Welsh Borderland. Bulletin of the British Museum (Natural History), Geology, 22 (2): 125-231. ALDRIDGE, R.J., JEPPSSON, L. & DORNING, K.J. 1993. Early Silurian oceanic episodes and events. Journal,

Geological Society of London, 150:501-513. BARRICK J.E. & KLAPPER, G. 1976. Multielement Silurian (late Llandoverian-Wenlockian) conodonts from the

Clarita Formation, Arbuckle Mountains, Oklahoma, and Phylogeny of Kockelella Palaeontologica, 10: 59-100.

Geologica et

BlSCHOFF, G.C.O. 1986. Early and Middle Silurian conodonts from midwestern New South Wales. Courier

Forschungsinstitut Senckenberg, 89: 1-337. COOPER, B.J. 1980. Towards an improved Silurian conodont biostratigraphy. Lethaia, 13: 209-227.

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CORRADINI, C. & SERPAGLI, E. 1999. A Silurian conodont biozonation from late Llandovery to end Pridoli in

Sardinia (Italy). In E. Serpagli & C. Corradini, (eds), Proceedings of the Seventh European Conodont Symposium. Bolletino delta Societa Paleontologica Italiana, 37(2-3): 255-273. L. 1997. A new latest Telychian, Sheinwoodian and early Homerian (Early Silurian) standard conodont zonation. Transactions of the Royal Society of Edinburgh: Earth Sciences, 88: 91-114.

JEPPSSON,

KLAPPER, G. & MURPHY, M.A. 1975.; Silurian - Lower Devonian conodont sequence in the Roberts Mountains

Formation of central Nevada. University of California Publication, Geological Sciences, 111: 1-62. (Imprint 1974) KLEFFNER, M.A. 1989.; A conodont-based Silurian chronostratigraphy. Bulletin, Geological Society of America, 101:904-912. LINK, A.G. & DRUCE, E.C. 1972. Ludlovian and Gedinnian conodont stratigraphy of the Yass Basin, New South

Wales. Bureau of Mineral Resources, Australia, Bulletin, 134: 1-136. MANNIK, P. 1998. New detailed conodont zonation for the Telychian, late Llandovery. In G. Bagnoli (ed), ECOS

VII Abstracts, Bologna-Moderna, 1998: 65-67. NICOLL, R.S. & REXROAD, C.B. 1969. Stratigraphy and conodont paleontology of the Salamonie Dolomite and

Lee Creek Member of the Brassfield Limestone (Silurian) in southeastern Indiana and adjacent Kentucky. Bulletin, Indiana Geological Survey, 40: 75pp. TALENT, J . A . , MAWSON, R., ANDREW, A.S., HAMILTON, P.J. & WHITFORD,

D.J. 1993. Middle Palaeozoic extinction events: faunal and isotopic data. Palaeogeography, Palaeoclimatology, Palaeoecology, 104: 139152.

VllRA, V. 1982. Late Silurian shallow and deep water conodonts of the east Baltic. In Ecostratigraphy of the east Baltic Silurian. 79-87. O.H. 1962. Conodontenchronologie des Silurs (=Gotlandiums) und des tieferen Devons mit besonderer Berucksichtigung der Formations-grenze. In H.K. Erben (ed) Symposiums -Band der 2 internal Arbeitstagung uber die Silur/Devon-Grenze und die stratigraphie von Silur und Devon, Bonn Bruxelles, E. Schweizerbart, Stuttgart. 2 8 1 - 2 8 7 .

WALLISER,

WALLISER, O.H. 1964.; Conodonten des Silurs. Abh. hess. Landesamt. Bodenforsch. Wiesbaden 41: 1-106. ZHOU, X.Y., ZHAI, Z . Q . & XIAN, S.Y. 1981. Guizhou zhiliuxi yaxingci shengwudiceng ji xing shu zhong (On

the Silurian conodont biostratigraphy and new genera and species in Guizhou Province/ Oil and Gas Geology, 2(2): 123-140.

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LATE ORDOVICIAN CONODONTS FROM THE "CARRIERS WELL FORMATION", NORTHEASTERN AUSTRALIA ANDREW SIMPSON Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia, asimpson@els.ma.edu.au The "Carriers Well Formation", lying east of the Gray Creek Fault Zone in the Broken River region of north Queensland (WLTHNALL 1993), consists of sporadically outcropping tracts of clastics with carbonate olistoliths and debris flows conspicuously charged with assorted carbonate lithologies. It has been argued recently (FEIST & TALENT 2000b) that, in the absence of carbonate olistoliths and carbonate clasts in debris flows, differentiation from the Wairuna Formation cannot be sustained, and that the latter should be utilized for all areas formerly referred to one or the other unit. TELFORD ( 1 9 7 2 ) listed eight conodont species from the "Carriers Well Formation" and suggested an Ashgill age. PALMIERI ( 1 9 7 8 ) also inferred an Ashgill age and correlated the unit with the Fork Lagoon Beds of the Anakie

Inlier. A revised species list was given by JELL et al. (1993). PALMIERI ( 1 9 8 4 ) sampled various localities thought to be the "Carriers Well Formation" and produced a similar conodont fauna. Icriodella superba and Belodina dispansa, previously unrecorded species, were recovered from two localities. A late Caradoc age was suggested for these. Further reconnaissance sampling by the Geological Survey of Queensland has recovered a small Late Ordovician conodont fauna from outcrops in Gray Creek and in the headwaters of Stockyard Creek. Conodonts include Amorphognathus ordovicicus, Plectodina Iflorida, Taoqupognathns tumidus, Aphelognathus Ifloweri, Belodina confluens, Pseudobelodina sp., Panderodus gracilis, Panderoduspanderi and Dapsilodus sp. More recent sampling by MUCEP staff and associates has included lengthy sections in the Big Stockyard Creek area and a more detailed section in highly prospective, well bedded dark carbonate lithologies further to the north (KAOS section) in an unnamed creek Sections in Stockyard Creek produced a meagre fauna consisting of Walliserodus sp., Pseudobelodina sp., IParoistodus sp., Panderodus gracilis, Panderodus panderi and ISagittodontina sp. The KAOS section by comparison yielded an abundant fauna dominated by Protopanderodus ssp.; other taxa include Walliserodus amplissimus, Scabardella altipes, Panderodus gracilis, Psuedobelodina linclinata, Psuedobelodina dispansa, Yoaxianognathus ani, Paroistodus sp., IGamachignathus sp., Strachanagnathus parvus, Plectodina florida, Phragmodus undatus, Oulodus sp., IStaufferella sp., and Plegagnathus sp. Many of these taxa are cosmopolitan Late Ordovician forms; the presence of A. ordovicicus indicating an Ashgill age. The occurrence of Taoqupognathus tumidus, however, is restricted to China and Australia. Taoqupognathus ranges from middle Caradoc to early Ashgill. ZHEN & WEBBY (1995) indicated that this genus is of considerable value for high precision correlation of Australian Late Ordovician sequences and noted that T. tumidus is a late form. Part of the "Carriers Well" Formation is closest in age (early Ashgill) to the Fork Lagoon Beds of the Anakie Inlier where A. ordovicicus and T. tumidus have been recovered (PALMIERI 1978). The recent discovery of an Early Ordovician trilobite low in one of the largest limestone olistoliths in the watershed of Big Stockyard Creek (FEIST & TALENT 2000b) increases the age-spectrum of carbonates derived from a now lost carbonate platform (west of the Hall Reward Fault (the Georgetown Carbonate Platform of FEIST & TALENT 2000b) from late Arenig through to perhaps early in the Llandovery. This information, taken in conjunction with data already published on the Camel Creek olistoliths and debris flows (SLOAN et al. 1995), and on the autochthonous carbonate sequences of the Broken River region (MAWSON & TALENT 1989, 1997; SLOAN et al. 1995; SIMPSON 1999, 2000; FEIST & TALENT 2000a, 2000b) accord with persistence of fundamentally the same carbonate platform through until late in the Devonian: to about the Givetian-Frasnian boundary.

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REFERENCES FEIST, R. & TALENT, J.A. 2000a. Devonian trilobites from the Broken River region of northeastern Australia.

Records of the Western Australian Museum, Supplement, 58 (in press). FEIST, R. & TALENT, J.A. 2000b. A new Early Ordovician trilobite from the Broken River region, northeastern

Australia: taxonomy and palaeogeographic implications. Records of the Western Australian Museum, Supplement, 58 (in press). JELL, J.S., SIMPSON, A.J., MAWSON, R. & TALENT, J.A. 1993. Biostratigraphic summary. In I . W . Withnall & S.C. Lang (eds.) Geology of the Broken River Province, north Queensland. Queensland Geology, 4: 2 3 9 - 2 4 5 . MAWSON, R. & TALENT, J.A. 1989. Late Emsian-Givetian conodont stratigraphy and biofacies—carbonate slope

and offshore shoal to lagoon and nearshore carbonate ramp—Broken River, north Queensland, Australia. Courier Forschungsinstut Senckenberg, 117: 2 0 5 - 2 5 9 . J.A. 1997. Famennian-Tournaisian conodonts and Devonian-Early Carboniferous transgressions and regressions in northeastern Australia. Geological Society of America Special Paper, 321:

MAWSON, R . & TALENT, 189-233.

PALMIERI, V. 1978. Late Ordovician conodonts from the Fork Lagoon Beds, Emerald area, central Queensland..

Queensland Geological Survey Publication, 369: 1-31. V. 1984. Conodont analysis of limestone samples from the Broken River Embayment, north Queensland. Queensland Geological Survey Records, 1984/38 (unpublished).

PALMIERI,

SIMPSON, A. 1999. Early Silurian conodonts from the Quinton Formation of the Broken River region (north-

eastern Australia). Abhandlungen der Geologischen Bundesanstalt, 54: 181-199. SIMPSON, A. 2000. Silurian to basal Devonian conodonts from the Broken River Crossing, northern Australia.

Records of the Western Australian Museum, Supplement, 58 (in press). SLOAN, T . R . , TALENT, J.A., MAWSON, R., SIMPSON, A.J., BROCK, G . A . , ENGELBRETSEN, M .J., JELL, J.S., AUNG, A.K., PFAFFENITTER, C., TROTTER, J. AND WITHNALL, I . W . 1995. Conodont data from Silurian-Middle

Devonian carbonate fans, debris flows, allochthonous blocks and adjacent autochthonous platform margins: Broken River and Camel Creek areas, north Queensland, Australia. Courier Forschungsinstitut Senckenberg 182:1-77. TELFORD, P.G. 1972. Lower and Middle Devonian conodont faunas from the Broken River Embayment, north

Queensland. Ph.D thesis, Department of Geology and Mineralogy, University of Queensland (unpublished). 1993. Stratigraphy of the Camel Creek Subprovince, In I . W . Withnall & S.C. Lang (eds.), Geology of the Broken River Province, north Queensland. Queensland Geology ,4: 15-34.

WITHNALL, I . W .

ZHEN, Y.Y. & WEBBY, B.D. 1995. Ordovician conodonts of the Cliefden Caves Limestone Group (Caradoc),

central New South Wales. Courier Forschungsinstitut Senckenberg, 182: 265-305.

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SILICIFIED EMSIAN (EARLY DEVONIAN) BRACHIOPODS FROM THE MURRINDAL LIMESTONE, BUCHAN, VICTORIA. JAMES L. VALENTINE Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Twenty seven horizons across two stratigraphic sections, Rocky Camp and McLartys Ridge, from the Murrindal Limestone of Buchan, Victoria , were sampled for brachiopods. Preliminary taxonomy indicates a diverse brachiopod assemblage totalling at least forty three genera, of which one, Dalmanellidae (Orthida) is new.

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THE EARLIEST RECORD OF FORAMINIFERAL LININGS AND MELANOSCLERITES, FROM THE LOWER CAMBRIAN LONTOVA FORMATION, ST PETERSBURG, RUSSIA T. WINCHESTER SEETO1 and D. MCILROY2 1

Centre for Ecostratigraphy and Paleobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Department of Earth Sciences, Liverpool University, Brownlow Street, Liverpool, L69 3GP, UK

Melanosclerites and foraminiferal test-linings, recovered from the lower Cambrian Lontova Formation, Russia, are the oldest known examples of each fossil. The Lontova Clay is a smectite-rich claystone, which has undergone little diagenesis, due to its position on the margin of the stable Siberian craton. The claystone is rich in the fossil agglutinated foraminifera Platysolenites and Spirosolenites, with exquisite preservation of foraminiferal tests, including the juvenile (prolocular) regions, which are otherwise unknown (MclLROY et al. 1994, LIPPS & ROZANOV 1996, MclLROY et al under review). While agglutinated foraminifera are known from the Precambrian-Cambrian transition, their tests are delicate and not commonly recovered from acid-digested samples. The organic test-linings found in the Lontova Clay preserve sufficient detail of the internal morphology of the foraminiferal test wall and gross morphology to allow identification to generic level. Foraminiferal taxa include Saccammina, Psammosphaera and a small, broken tubular form ('Wathysiphon), which supplements the previously described Platysolenites spp., Spirosolenites spiralis and Psammosphaera sp which are known from their agglutinated tests. This extends the lower range of Psammosphaera and Saccammina to the Platysolenites partial range zone. Melanosclerites are organic microfossils of uncertain affinity, first identified by Alfred Eisenack, and were previously only known from palynological residues ranging from the Middle Ordovician (Darriwilian) to the Late Devonian (Frasnian). Exclusively marine, they are most likely related to hydrozoans. The occurrence of melanosclerites in the Lontova Clay, extends their lower range from the Ordovician to the sub-trilobitic lower Cambrian and includes Semenola semen SCHALLREUTER 1981, and species of Melanosteus EISENACK 1942 and possibly Melanoclava EISENACK 1942. REFERENCES J. & ROZANOV, A.Yu 1996. The late Precambrian-Cambrian agglutinated fossil Platysolenites. Palaeontological Journal, 10: 687-697

LIPPS,

MclLROY, D., GREEN, O.R. & BRAISER M.D. 1994. The world's oldest foraminiferans. Microscopy and Analysis,

44: 13-15. (in review) Paleobiology and evolution of the earliest agglutinated foraminifera: Platysolenites, Spirosolenites and related forms. Submitted to Lethaia MclLROY, D., BRASIER, M . D . & GREEN, O . R .

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FIRST REFORT OF AN ICHTHYOLITH FAUNA CLOSE TO THE PERMIAN TRIASSIC BOUNDARY FROM A SECTION IN SOUTH OF ESFHAN, CENTRAL IRAN MEHDI YAZDI and M. MANIZHEH SHIRANI Department of Geology, University of Esfahan, Iran An abundant ichthyolith remains, conodonts and Holothurian sclerites were recovered near Permian/Triassic boundary from a section, south of Esfahan. Recovered fauna includes shark microremains comprise teeth and scales. Conodonts species are mostly Neogondolellids. The Ichthyolith materials are similar to Fasanian ichthyoliths from Zakazane area in the Slovak karst of the Western Carpathians (SALAJ & PEVNY 1998) which represent subspecies of Acodina triassica. This is the first report regarding to the shark-microremain assemblage from Iran. These microvertebrates are associated with species of Gondolellidae that new data on the age of fauna will be published in future. REFERENCES SALAJ, J. & PEVNY, J. 1998. Fasanian Ichthyolites from the locality Zakazane in the Slovak karst of the Western Carpathians. Zemni Plyn a Nafta, 42: 269-281.

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FIRST REPORT OF PROBABLY CARBONIFEROUS DARCHALEH AREA (EASTERN SHAHREZA, IRAN)

MICROVERTEBRATES

FROM

THE

MEDHI YAZDI and ZAHRA RABLEY Department of Geology, University of Esfahan, Iran A considerable number offish teeth and scale remains were recovered from a section in the Darchaleh area (10 km northeast of Shahreza, south of Esfahan), which are probably Carboniferous in age. The microvertebrate assemblage comprises many scales and teeth related to actinopterygians and palaeoniscoids. Based on systematic sampling, these materials come from a limestone bed which is located below the conglomerate unit. This unit dated by. SAFARI & YAZDI ( 1 9 9 8 ) has an age-range of Post Westphalian to Early Permian. This time Interval is attributable to the conglomerate horizon which is related to Late Carboniferous palaeoevents in Central Iran. The presence of a crinoidal bed in this locality similar to one in the Eastern part of Iran (Shotori Range, Howz-eDorah) confirms that, possibly during late Numurian to the beginning of the Westphalian, this locality experienced the same palaeoenvironmental conditions with regard to depth of water. REFERENCES SAFARI, A. & YAZDI, M . 1998. Post Westphalian (Late Carboniferous) palaeoevents. In Central Iran.

In-R. Mawson, J. Talent, G. Wilson and P. Cockle, (eds.): Abstract book, Esfahan Meeting of UNESCO- IGCP 421. p.31.

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GEOCHEMISTRY OF EARLY SILURIAN (WENLOCK) GRAPTOLITE EXTINCTIONS: CAPE PHILLIPS FORMATION, ARCTIC CANADA M.K. ZIMMERMAN 1 , P.J. NOBLE 1 , C. HOLMDEN 2 and A.C. LENZ. 3 1 2 3

Department of Geological Sciences, University of Nevada, Reno, Reno, NV 89557-0138, USA Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada Department of Earth Sciences, University of Western Ontario, London, ON, N6A 5B7, Canada

The Canadian Arctic is renowned for its thick exposures of Ordovician and Silurian carbonates and exceptional preservation of graptolitic faunas in a shelf sea environment. We present chemostratigraphic data integrated with graptolite biostratigraphy from two measured sections, the Abbott River section, Cornwallis Island and the more basinal Twilight Creek section, Bathurst Island (160 km outboard of Abbott River). These data provide a close look at the geochemical response to various biotic events in two slightly different environmental settings, including three globally recognized extinction events throughout the Wenlock. Cape Phillips Formation is composed of laminated to thinly-bedded silty carbonates that were deposited along the broad outer shelf of Laurentia near the Silurian equator. Four noteworthy chemostratigraphic events are recognized throughout the Wenlock and are discussed below. These events occur in relatively lithologically uniform sections and are not facies related. Instead, these events are interpreted to be indicative of changes in the Wenlock carbon cycle. At Twilight Creek, a +2.6%o 6,3C0rg shift occurs at 28m. It occurs at or near an early Sheinwoodian extinction event (Ireviken Event), which occurs between 27 and 29 m, based on graptolite field identifications. This excursion is followed by a -4%o shift into the late Sheinwoodian-early Homerian. The 8,3Corg shift is nearly paralleled by the 5,3Cinorg signature, that shows a +2.2%o shift followed by a -3.1%o shift. An increase in total organic carbon (TOC) and a decrease in carbonate accompany the positive carbon isotope shift, a possible reflection of increased burial of organic matter in cool, reducing marine waters. Likewise, a 3%o-4%o enrichment of 5 l 3 C i n 0 rg is recognized across this extinction interval in Gotland, Estonia, and Australia suggesting global changes in the Wenlock carbon cycle. The early Homerian extinction interval {lundgreni Event) contains a transient +2.5%o 5 ,3 C org enrichment at Twilight Creek (± 3 m of the extinction) and +3.5%o at Abbott River (± 2 m of the extinction). This is the first time this excursion has been recognized anywhere, possibly due to our close interval sampling across this extinction interval. However, no distinctive enrichment in 813Cinorg is observed in this interval. Increased TOC coincides with this extinction interval and XRD results show the first appearance of pyrite is also coincident. The post-lundgreni graptolite fauna (nassa Zone) is characterized by a low diversity, but abundant and opportunistic species. Positive 5,3C0rg and 813Cinorg excursions are recognized at the Twilight Creek (5 ,3 C org +2.5%o, 8 , 3 C i n 0 rg +0.4%o) and Abbott River sections (8 , 3 C o r g +2%o, 8 13 C in0 rg +0.9%o) and are coeval within the resolution of our data. This enrichment is followed by a gradual depletion into the ludensis Zone. Previous workers have recognized a slight 8 ,3 Ci„ 0 rg positive peak in the nassa Zone on Baillie-Hamilton Island just north of Cornwallis Island, and in Estonia and Gotland. This excursion has previously been explained as enhanced bioproduction due to graptolite recovery following the lundgreni Event. The late Homerian extinction interval (ludensis Event) is characterized by small variations in 813Corg of <l%o at both Twilight Creek and Abbott River. Although no large carbon isotope shifts coincide with the ludensis Event, an increase in TOC and decrease in carbonate do occur at the boundary. Low 8!3Cinorg values are recognized in the Arctic during the late Homerian (late Wenlock) similar to previous observations in England and Estonia, but in contrast to those in Gotland. Phosphate nodules are present in the late Homerian at the Twilight Creek section, possibly indicative of upwelling of cool, nutrient-rich waters. Both the 8 ,3 C org and 8 ,3 C inorg show positive excursions followed by a gradual negative decline at both the Ireviken Event and in the nassa Zone. Otherwise there is little correlation between the two. Lack of correlation may be explained because the 8,3Cinorg is providing a shelf signature whereas the 8 ,3 C org is providing an independent signature of the oceanic plankton. In cases where they correlate, it suggests that factors controlling the excursions in the plankton signatures are likewise affecting the carbonate shelf (i.e. ocean-atmosphere effects).

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