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Geological Society of Australia ABSTRACTS Number 87

REGOLITH: MINERAL DEPOSITS & ENVIRONMENT

Sprigg Symposium Adelaide 29 November 2007 Editors B.J. Cooper and J.L. Keeling

Geological Society of Australia ABSTRACTS Number 87

REGOLITH: MINERAL DEPOSITS & ENVIRONMENT

Editors: B.J. Cooper and J.L. Keeling

Sprigg Symposium Mawson Theatre University of Adelaide 29 November 2007 ISSN Number 0729 01IX

Sponsored by

Government of South Australia

CRCLEME

Primary Industries and Resources SA Cc-'tro for

Landscape Environments and Mineral Exploration

' Geological Society of Australia Incorporated - 2007

ISSN 0729 OllX Preferred citation for this volume: Cooper, BJ. and Keeling, J.L. 2007 (editors). Sprigg Symposium, November 2007: Regolith, Mineral Deposits and Environment, Geological Society of Australia Abstracts No. 87, 82p Example citation for papers in this volume Petts, A.E. and Hill, S.M. 2007. Termitaria as regolith and landscape attributes: A case study from Titania Au-prospect, N.T. In Cooper, B.J. and Keeling, J.L. 2007 (editors). Sprigg Symposium, November 2007: Regolith, Mineral Deposits and Environment, Geological Society ofAustralia Abstracts No. 87, pp. 62-66.

Copies of this publication may be obtainedfrom: The Business Manager Geological Society of Australia Incorporated Suite 706, 301 George Street Sydney NSW 2000 Australia or on-line at www.shop.gsa/org.au

Sprigg Symposium, Adelaide, November 2007

Geological Society of Australia Abstract No. 87

PROGRAMME 8:00 am

Registration

8:45

G. Taylor:

Welcome address

Session 1 Chair: G. Taylor 9:00

J.L. Keeling:

Dr. R.C. Sprigg - Contributions to geology and insights into landscape evolution

9:20

Invited address S.L. Rogers: Recent developments in regolith research with application to mineral exploration and environmental management

9:40

M.J. Lintern: Gold in calcrete - 20 years on

10:10

B.J. Cooper: Sedimentary uranium: How it was first discovered in the Frome Embayment

10:30

Morning Tea - Sprigg Room, Level 1 - Posters on display

Session 2 Chair: J.L. Keeling 11:10

A.J. Fabris:

Surface geochemical expression of bedrock beneath thick sediment cover, Curnamona Province, South Australia

11:30

R.W. Fidler: Reduce, reuse, recycle: The Gawler calcrete reanalysis project

11:50

S. Pontual:

Spectral characteristics of regolith materials and application to mineral exploration

12:10

A. Mauger:

Spectral mapping mineral alteration in the Central Gawler Gold province -Tarcoola case study

12:30pm

Lunch - Sprigg Room, Level 1 - Posters on display

111

Sprigg Symposium, Adelaide, November 2007

Geological Society of Australia Abstract No. 87

Session 3 Chair: S.L. Rogers 1:30 pm

M. J. Sheard: Gawler Craton regolith benchmarking: origins, types, utility and where

1:50

R.C. Dart:

Improving the reliability of Au-in-calcrete anomalies through the use of regolith-landform mapping and detailed assay analysis

2:10

J.E. Davey:

Incorporating surficial geology and the sedimentary record into tectonic driven landscape models

2:30

A.E. Petts:

Termitaria as regolith and landscape attributes: A case study from Titania Au prospect, NT.

2:50

Afternoon Tea - Sprigg Room, Level 1 - Posters on display

Session 4 Chair: S.M. Hill 3:30

J. Joseph:

Electromagnetics for mineral exploration and environmental studies: Results from South Australia and Northern Territory

3:50

A. Brown:

Soil vs. Biogeochemical expression of mineralisation buried by transported regolith: White Dam, Cu-Au, Curnamona Province, SA

4:10

N. Reid:

Biogeochemical prospecting in the Tanami Desert

4:30

M. Nemanis: Plant biogeochemical expression of the Four Mile uranium mineralisation - Frome Embayment, South Australia

4:50

G Taylor:

5:00 pm

Wine Tasting - Sprigg Room, Level 1 - Wine Innovation Pty Ltd

Closing Remarks

Geological Society of Australia Abstract 87

Sprigg Symposium Adelaide, November 2007

POSTERS "Constraints on the Four Mile uranium mineralisation resulting from neotectonic activity in the northern Flinders Ranges" C.D. Dubieniecki & S.M. Hill

"Uranium mineralisation expression and dispersion in the regolith carbonatebedrock-plant system near the Four Mile West uranium prospect" D. J. Gallasch & S. M. Hill

"Upper Four Mile Creek palaeosediments and associated palaeolandscape reconstructions, Eromanga Basin, northern Flinders Ranges, South Australia" A.N. Hector &S. M. Hill

"Biogeochemical trace element cycling over the Four Mile West uranium mineralisation by invertebrate soil biota" M. F. Jennings, S. M. Hill, C. Wright & J. Kirby

"Biogeochemical and geochemical expressions of uranium prospectivity across the Four Mile Creek catchment. South Australia" J.M.P. McMahon&S.M. Hill

Sprigg Symposium, Adelaide, November 2007

Geological Society of Australia Abstract No. 87

CONTENTS (Presenter indicated with asterisk *)

Page

Brown, A.D * and Hill, S.M. Soil vs. Biogeochemical expression of mineralisation buried by transported regolith: White Dam, Cu-Au, Curnamona Province, SA Cooper, B.J.* Sedimentary uranium: How it was first discovered in the Frome Embayment

Dart, R.C HIM, S.M., Barovltch, K.M., and Chittleborough, DJ. Improving the reliability of Au-in-calcrete anomalies through the use of regolith-landform mapping and detailed assay analysis

Davey, J.E.* and Hill, S.M. Incorporating surficial geology and the sedimentary record into tectonic driven landscape evolution models

Dubienleckl, C.D.* and Hill, S.M. Constraints on the Four Mile uranium mineralisation resulting from neotectonic activity in the northern Flinders Ranges

Fabris, A.J.*, Keeling, J.L. and Fidler, R.W. Surface geochemical expression of bedrock beneath thick sediment cover, Curnamona Province, South Australia

Fidler, R.W.* Reduce, reuse, recycle: The Gawler calcrete reanalysis project

Gallasch, D.J.* and Hill, S.M. Uranium mineralisation expression and dispersion in the regolith carbonate-bedrock-plant system near the Four Mile West uranium prospect

Hector, A.N.* and Hill, S.M. Upper Four Mile Creek palaeosediments and associated palaeolandscape reconstructions, Eromanga Basin, northern Flinders Ranges, South Australia

Jennings, M.F.*, Hill, S.M., Wright, C. and Kirby, J. Biogeochemical trace element cycling over the Four Mile West uranium mineralisation by invertebrate soil biota

Geological Society of Australia Abstract No. 87

Sprigg Symposium, Adelaide, November 2007

Page

Joseph, J.*, Fabris, A. and Worrall, L. Electromagnetics for mineral exploration and environmental studies: Results from South Australia and Northern Territory

Keeling, J.L * and More, S.B. Dr. R.C. Sprigg - Contributions to geology and insights into landscape evolution

Lintern, M.J * Gold in calcrete - 20 years on

Mauger, A.J.* and Keeling, J.L Spectral mapping mineral alteration in the Central Gawler Gold province Tarcoola case study

McMahon, J.M.P * and Hill, S.M. Biogeochemical and geochemical expressions of uranium prospectivity across the Four Mile Creek catchment, South Australia

Neimanis, M Hill, S.M and Hore, 8. Plant biogeochemical expression of the Four Mile uranium mineralisation Frome Embayment, South Australia

Petts, A.E.* and Hill, S.M. Termitaria as regolith and landscape attributes: A case study from Titania Au prospect, NT.

Pontual, S.* Spectral characteristics of regolith materials and application to mineral exploration

Reid'N.*, Hill, S.M. and Lewis, D.M. Biogeochemical prospecting in the Tanami Desert

Rogers, S.L. * Recent developments in regolith research with application to mineral exploration and environmental management

Sheard, M.J. * Gawler Craton regolith benchmarking: Origins, types, utility and where

Vll

Geological Society of Australia Abstract No. 87

Sprigg Symposium, Adelaide, November 2007

SOIL Vs BIOGEOCHEMICAL EXPRESSION OF MINERALISATION BURIED BY TRANSPORTED REGOLITH: WHITE DAM, Cu-Au, CURNAMONA PROVINCE, SA A.D, Brown^ and S.M. Hill^ ^ School of Earth & Environmental Sciences, University of Adelaide, Adelaide, Australia, 5005 ^ CRC LEME, The University of Adelaide, Adelaide, Australia, 5005

INTRODUCTION Location The White Dam prospect is approximately 31 km NE of Olary in South Australia (Fig. 1)

Figure 1. White Dam location map

Background Due to the poor expression of shallow-buried CuAu mineralisation by traditional geochemical exploration, a program of regolith-landform mapping combined with geochemical and biogeochemical sampling has been carried out to better understand the limitations of the exploration geochemistry, and to improve the expression of mineralisation. The integration of bio and geochemical assays with regolithlandform mapping has highlighted the effects of changes in landscape position and regolith materials on the expression of mineralisation in areas of low relief and shallow cover.

EXPLORATION HISTORY The White Dam Cu-Au deposit was discovered by Aberfoyle Resources after a reconnaissance soil survey of parts of the 300 km^ of regolithdominated terrain on the western margins of the Mundi Mundi Plains. Soil sampling (<75 micron fraction) was conducted on a 1 km spaced grid, using airphotos for location control, and samples were collected preferentially from sites at the base of slopes (McGeough and Anderson, 1998).

Subsequent 500 m grid sampling in the White Dam area generated locally anomalous Au results, with follow up exploration in 1994-95, when MIM entered into a joint venture agreement with Aberfoyle Resources and Normandy Exploration. MIM's geochemical sampling strategy at White Dam used 100 m line spacing and involved two main techniques: 1) in areas of subcrop or shallow outcrop on erosional rises, a minus 80 mesh sample was collected; and, 2) in depositional areas a 3 kg bulk sample was collected for Bulk Leach Extractable Gold (BLEG) analysis. Based on promising geochemical results, MIM Exploration drilled five RC percussion holes in December 1996. Due to rains and extensive flooding in the Olary area, further drilling was postponed until May 1997 when a further 8 RC holes and 5 HQ cored holes were drilled. Subsequently a detailed drilling program was commenced with over 130 RC percussion holes and NQ diamond cores drilled. Drilling delineated a substantially larger orebody than indicated by geochemical surveying. As little as 1 m of transported regolith was enough to conceal significant underlying bedrock mineralisation within the earlier soil sampling programs. As much as 2/3rds of the mineralisation is overlain by transported cover, with only one sample showing relatively high Cu and Au through the transported cover. Instead, high Au assays were related to a sub-cropping, weakly mineralised 'tail' of the mineralisation. Other high Cu and Au assays from soils within the area were also drilled however they were found to be unrelated to underlying mineralisation. This has been attributed to poorly constrained variations in regolith conditions across the prospect (McGeough and Anderson, 1998). Recent drilling by Polymetals and EXCO Resources was followed with excavation of 6 costeans to obtain bulk samples for column leach test work. These also provided excellent exposures of the mineralisation system (Cooke, 2003) and overlying regolith profiles. Regolith research has been conducted across the

Geological Society of Australia Abstract No. 87

prospect and has included detailed regolithlandform mapping and characterisation (Brown et al., 2003; Brown and Hill, 2003a, Brown and Hill, 2003b) as well as regional regolith-landform mapping (Lau et al., 2004) and remote sensing (Lau et a/., 2003).

WHITE DAM REGOLITHLANDFORM SETTING The White Dam mineralisation occurs within a landscape with subdued topography and limited bedrock exposure. The area is within the upper Mingary Creek catchment, which is a part of the Lake Eyre Basin, discharging into the Strzelecki Desert dunefield south of Lake Frome. Alluvial and sheet flow depositional plains and low rises extend across much of the mineralisation area. The transport of surface materials is dominated by shallow overland flow (dominated by sheet flow). Alluvial sediments occur along the creek channel and associated alluvial plains to the north, while aeolian sediments are a component of most regolith materials, but do not entirely account for depositional landforms in their own right. Limited exposures of weathered bedrock flanked by mixed sheet flow and aeolian sediments occur within low hills to the north and low erosional rises to the south. The vegetation is mostly part of a chenopod shrubland, dominated by bladder saltbush (Atriplex vesicaria) and black bluebush (Maireana pyramidata), and some pearl bluebush (Maireana sedifolia). Rosewood trees (Alectrylon oleofolius) occur sporadically near bedrock exposures and subcropping regolith carbonate accumulations (RCAs), while belah {Casuarina pauper) occurs on some alluvial plains and fans. The climate is semi arid with an annual average rainfall less than 245 mm. Mean minimum and maximum temperatures are about 17-33° C (January) and 4-15° C (July) (Bureau of Meteorology, 2004). The land has been used for pastoral sheep grazing since the late 1800s.

REGOLITH MATERIALS Regolith materials vary across the mineralisation area, including: • skeletal soils associated with slightly weathered bedrock (saprock) exposures in the south. • up to 4 m thick, red-brown alluvial silts and clays in the north east. • quartzose and lithic, red-brown, colluvial silts and clays across remainder of the area. These transported regolith materials overlie kaolinitic saprolite ranging from <1 m up to 50 m deep towards a major North-South trending fault in the west of the mineralisation zone. Post

Sprigg Symposium, Adelaide, November 2007

pastoral sediments consisting of mixed colluvial and aeolian sediments extend across of the upper 0.1 m of regolith in the prospect. Multiple generations of regolith carbonate accumulations (RCAs) occur as powdery mottles and rhizomorphs underlying the alluvial plains and depositional plains flanking the creek, and nodular and fragmented hardpan RCAs within the thinner cover on the erosional rises to the south.

GEOLOGICAL SETTING The White Dam prospect occurs within Wiperaminga subgroup of the Palaeo-proterozoic Willyama Supergroup within the Curnamona Province. The Au-Cu mineralisation is hosted within leucocratic banded gneiss, and is structurally controlled by faults to the north and south, and west. Gold is concentrated in the oxide zone associated with biotite-rich selvedge and leucocratic bands and veins within the gneiss (Cordon, 1998. Cooke, 2003). Compared with other Au-Cu prospects in the district. White Dam has relatively low Fe contents and does not show elevated levels of As, Ag, Ni, Cd, Sb or Pb (Cordon, 1998). Bedrock lithologies around the White Dam deposit include albitite and minor granitiods in the low erosional rise to the south, and amphibolite lenses intruding the gneiss in the eastern portion of the mineralisation.

GEOCHEMICAL ASSAYS Geochemical sampling was carried out with an emphasis on sampling a consistent media across the prospect. Following 1:2000 R-L mapping (Brown and Hill, 2003) the uppermost 2 cm of topsoil was sampled at 70 sites on a 50 x 50 m grid. At each site loose vegetation litter and large lithic debris was scraped away, and a 2.5 kg sample was collected using a plastic scoop. The <75 um fractions was selected from topsoil samples, based on an orientation survey as part of this study, this was consistent with previous orientation studies in the Olary Domain (Skwarnecki et al, 2001). Au and Cu assay results from the topsoil samples show an improvement from the existing company data, and both highlight the effect of the subtle topography and regolith materials on the expression of mineralisation (Figs 2 & 3). Au was detectable in 52 of the 70 topsoil samples, with relatively high assay results obtained from samples over sub-cropping mineralisation, including a high grade mineralised zone that is overlain by 4 m of transported cover (CHpd3, Fig. 2). On the topographically lower landforms to the south-west of the mineralisation Au was below the detection limit of the assay method, with the exception of some samples along Bulloo Creek and adjacent alluvial fans and

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Geological Society of Australia Abstract No. 87

plains. There is however detectable Au in all samples to the north-east of the mineralisation. This dilution/depletion to the SW and the presence of detectable Au assays to the NE fits well with the predominantly N to NE dispersion vectors mapped across the prospect from measurement of litter dam orientations (Brown & Hill, 2003a; 2003b). Cu was detectable in all 70 samples, with the relatively high assay results largely restricted to the area of sub-cropping mineralisation.

detectable assays were from an alluvial plain flanking Bulloo Creek and another site 100 m NE of the high-grade zone of mineralisation on a

100

Cu Soils

200

23-33ppm

X 3a-54ppm

90-130ppm

400 +

Meters

54-90ppm

130-190ppm

Figure 3. Cu assays <75 urn soil samples

Au Soils

X 1-11ppb

• 'V^ • +

11-33ppb 0

• ^Y^

33-50ppb ^

50-71ppb

Figure 2. Au assays -75 urn soil samples

The mapping of assay results reflect dispersion downslope onto the large depositional plain to the NE of the prospect. Copper results show a distinct dilution/depletion zone in the SW, extending across the mineralisation along the CHep and CHpd4 RLUs (Fig. 3) in a similar way to the pattern of Au assays.

BIOGEOCHEMICAL ASSAYS The Au and Cu assays from the bladder saltbush twig samples highlight the significance of landform effects when interpreting these biogeochemical survey results. Gold was detectable in 9 of the 70 samples assayed (Fig. 4). Seven detectable Au assays were from sites overlying or immediately adjacent to the surface projection of the mineralisation. Four of these samples were adjacent to mineralisation in the S of the area, where the mineralisation is buried by approximately 1 m of transported regolith. The other 3 results were located over the high- grade zone of mineralisation, which is overlain by 4 m of transported regolith. The remaining 2

400

Au Veg V

1,2-1.72ppb

1-72-2.8ppb

2.8-3.3ppb

3.3-8.08ppb

Meters

Figure 4. Au assays bladder saltbush twigs

depositional plain (CHpda Fig. 4). These are both interpreted as transported and redeposited Au contents. The lack of detectable Au assays in the area of sub-cropping mineralisation may reflect poor bioavailability of Au in areas of skeletal soil

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cover. The 3 detectable Au assays from over the high grade mineralisation zone indicate that even where the transported regolith is at its maximum thickness the plant can incorporate it into its tissues. Copper was detected in all 70 samples assayed, and all anomalous values are overlying or adjacent to the area of known mineralisation. The Cu results in the bladder saltbush show dilution/depletion to the SW of the mineralisation, and over the mineralisation on the erosional plain (CHep, Fig. 5) and depositional plain (CHpd4, Fig. 5). This again fits well with the interpretation of materials being transported in a NE direction across the prospect, with non-mineralised material being carried in from the SW. Copper assays also reflected the zone of higher grade mineralisation, through 4 m of transported cover.

400 Meters

Cu Veg c

5-6ppm

6-9ppm

9-12ppm

12-20pp;m

Figure 5. Cu assays bladder saltbush twigs

MINERAL EXPLORATION SIGNIFICANCE The previous exploration in this area raised several major concerns for further exploration programs in landscapes with shallow regolith. Although transported cover was less than 4 m thick, the mineralisation signatures in the soil samples were restricted to sub-cropping mineralisation. A few 'false anomalies' were obtained during the soil sampling program that later drilling showed were underlain by unmineralised bedrock. The magnitude and dimensions of the area of relatively high Cu and Au assays did not correspond with the grade and extent of the mineralised zone within the

underlying weathered bedrock. The shallow transported regolith that had obscured previous exploration expressions of buried mineralisation is widespread across the region, and has therefore potentially been a major impediment to previous exploration success. When compared to soil geochemistry, biogeochemical sampling has been able to provide better expression of mineralisation in areas of shallow cover and can be interpreted with more confidence. References BUREAU OF METEOROLOGY 2004. Yunta http://www.bom.gov.aU/climate/averages/tables/t ext/cw_020026.csv BUREAU OF METEOROLOGY 2004. Broken Hill http://www.bom.gov.aU/climate/averages/tables/t ext/cw_047007.csv BROWN A , HILL S. & JAMES P. 2003 Detailed regolith mapping as a tool for refining the interpretation of geochemical results at White Dam, Curnamona Craton, SA. In Peljo M., Comp. 2003. Broken Hill Exploration Initiative: Abstracts from the July 2003 conference. Geoscience Australia Record 2003/13. BROWN A.D. & HILL S.M. 2003a. Litter Dams: A new method of mapping surface dispersion vectors at the White Dam Prospect, Curnamona Craton, SA. In: ROACH, I.C. ed Advances in Regolith, 24-28. CRC LEME. BROWN AD. & HILL S.M. 2003b. White Dam- detailed regolith-landform mapping as a tool for refining the interpretation of surface geochemical results. Primary Industries and Resources S.A. MESA Journal 6-8. COOKE A. 2003. White Dam, an exciting new gold project in the Curnamona Province. Primary Industries and Resources S.A. MESA Journal, 31,4-5. CORDON E.L. 1998. An investigation into the mineralisation of the White Dam prospect, Olary Block, South Australia. University of Adelaide, B.Sc. Hons thesis (unpublished). LAU I.e., MAUGERAJ., HEINSON G. & JAMES, P.R. 2003. Remote spectral mapping of regolith in the Olary Domain. In PELJO M. comp. 2003. Broken Hill Exploration Initiative: Abstracts from the July 2003 conference. Geoscience Australia Record 2003/13. LAU I., HEINSON G.S., & HILL S.M. 2004. Explanatory notes for the 1:30,000 Regolithlandform map of White Dam, Olary Domain, South Australia. In ROACH I.C. ed. 2004. Regolith 2004. CRC LEME, 188-193. MCGEOUGH M. AND ANDERSON J.A. 1998. Discovery of the White Dam Au-Cu mineralisation. AGSO Record 1998/25: 69-71. SKWARNECKI M.S., LI SHU & LINTERN M.J. 2001. Geochemical dispersion in the Olary District, South Australia: Investigations at Faugh-aBallagh Prospect, Olary Silver Mine, Wadnaminga Goldfield and Blue Rose Prospect, CRC LEME open file report 113.

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Sprigg Symposium, Adelaide, November 2007

SEDIMENTARY URANIUM: HOW IT WAS FIRST DISCOVERED IN THE FROME EMBAYMENT B.J. Cooper Primary Industries and Resources South Australia GPO Box 1671 Adelaide SA 5001

INTRODUCTION Economic resources of uranium were first discovered in the Frome Embayment of South Australia in 1969 thus revealing a "new sedimentary uranium province" (Johns, 1970). This paper explores the historical circumstances behind this discovery given that South Australia had, by then, been subject to uranium exploration over more than 60 years.

EARLY MISCONCEPTIONS South Australia's first uranium explorers focussed their efforts on "granite country" and this orientation meant that sedimentary basins were generally ignored in uranium exploration until the late 1960s (see for example Laby & Mawson 1905; Whittle 1954). Such a focus was successful in the delineation and mining of uranium resources at Radium Hill (1909-15, 1925, 1954-61) and Mount Painter (1911-14, 1926-7, 1932, 1934, 1949). During this early period, there were at least two radical thinkers who promoted sedimentary uranium, but they were not taken seriously. The reader is directed to E. de Hautpick (1929) and the reference to R.G. Thomas' s views from 1944 in Sprigg (1984, p. 54, 233). Until the 1960s, South Australian geologists did not appreciate that under surface conditions uranium has anomalously high solubility, when compared with other metals. This leads to its ready dissolution, ease of transport and potential precipitation in reducing environments, where sandstones rich in organic material, organic shales, coals and high pH phosphate sediments can all concentrate uranium. South Australian historical ignorance was exacerbated by the lack of outcropping uraniferous material, such outcrops leading to their early investigation in sedimentary terrains in the United States.

U.S. EXPERIENCE Through the 1940s to the 1970s extensive research took place in the United States into the occurrence and genesis of sedimentary uranium on the Colorado plateau and later, further north in

Wyoming. The potential value of uranium for nuclear power generation was recognised by the early 1960s and increased interest in uranium exploration, world wide, was a consequence. In 1967, Chief Geologist Phil Ellsworth of the Kerr McGee Corporation, one of the major US uranium exploration and production companies, visited South Australia. The company had already successfully explored Wyoming for sedimentary uranium and recognised potential in the State. An exploration licence was taken out over part of Eyre Peninsula and a programme of non-cored drilling with down hole logging of Cenozoic successions was initiated.

BEVERLEY DISCOVERY With US interest in South Australia's sedimentary uranium, the local response was quick. Consulting geologist Brian Fitzpatrick visited the US. Given that the Petromin group, with which Fitzpatrick was associated, already had uranium exploration tenements over Mount Painter crystalline rocks, it was a simple extension to secure exploration acreage in April 1968 over the vacant and unexplored sedimentary region of the Frome Embayment that was adjacent. Entrepreneur Bill Siller, who had been involved with Mereenie gas field discovery, sourced the exploration capital. In little more than 18 months, the Petromin Group completed an aerial survey, commenced pattern drilling and discovered the Beverley uranium resource in November 1969 (Haynes 1875). It was named after Bill Siller's wife.

HONEYMOON DISCOVERY The discovery of additional uranium resources in the Frome Embayment required more sustained effort and this was forthcoming through the independent efforts of Eric Rudd, Professor of Economic Geology, University of Adelaide on one hand and the so-called Minad-Teton Joint Venture on the other. The latter was a collaboration between the Queensland based Mines Administration Pty Ltd (later to be fully owned by CSR Ltd) and the US-based, Teton Exploration Drilling Co Pty Ltd of Wyoming. For

Geological Society of Australia Abstract No. 87

both groups interaction with US based sedimentary uranium explorers was critical. In the case of the Minad Teton Joint Venture, Teton seconded a US geologist on a semi permanent basis to Australia whilst Minad's expertise was also enhanced by sending geologist David Brunt to the US for an extended period in 1972. Eric Rudd commenced exploration in January 1969 using his personal consulting company. He assessed the Mesozoic as well as the Cenozoic sedimentary succession as possible targets focussing on areas adjacent to known basement uranium occurrences in the Olary region. Appreciating the solubility of uranium, Rudd then re-examined all water well information and collected new water samples to check for any presence of radioactivity. This was followed by a review of aeromagnetic surveys, previously undertaken by petroleum explorers, to determine basement highs thus beginning determination of palaeodrainage channels. A programme of drilling in late 1969 included holes that were located extremely close to the Gould's Dam uranium resource, however this deposit was not ultimately discovered until November 1974. By February 1970, Rudd was exploring for "fronts in the sands between oxidised and unoxidised areas" and was thus fully cognisant of the so-called roll front model for sedimentary uranium that had been proposed by US explorers. Carpentaria Exploration Pty Ltd, the exploration subsidiary of Mt Isa Mines Pty Ltd, first detected anomalous uranium in sediments at the end of 1971 in their exploration area located within and adjacent to the Olary region. In September 1972 they entered into a joint venture with the Minad-Teton group covering the Frome Embayment sector of their licence area. Within two months, Minad's David Brunt, and Teton's Gunny Jarre had determined economic concentrations of uranium along the edges of a buried palaeochannel, which became known as the Yarramba palaeochannel. Alteration characteristics, contained radioactivity and thickness of basal sand were the most useful criteria in their successful exploration. Following a further joint venture in September 1974 with adjacent exploration tenement holder. Sedimentary Uranium NL, the Minad-Teton alliance determined the full extent of what became known as the Honeymoon deposit (Brunt, 1978).

Sprigg Symposium, Adelaide, November 2007

GOVERNMENT ASSISTANCE Following the Beverley discovery, the Geological Survey of South Australia played a major role in supporting the search for sedimentary uranium in the Frome Embayment. Intensive field mapping of the Frome Embayment began in 1970/1971 with publication of the first 1:250,000 map sheet by Callen (1975). In June 1972, stratigraphic drilling was undertaking at Wooltana, Yalkalpo and Wertaloona that assisted development of the Cenozoic stratigraphic framework for geological mapping whilst also contributing to uranium exploration. Supporting age-determinations, using fossil spore -pollen (palynology) were also undertaken by the Government. In addition experimental ground geophysical surveys including gravity, resistivity and magnetics were completed by Government geophysicists during 1971. This assisted palaeodrainage channel determination, through targeting the outline of basement relief thus providing a base for the discovery of the Gould's Dam resource (Ellis, 1980). References BRUNT D A 1978. Uranium in Tertiary Stream Channels, Lake Frome area, South Australia. Proceedings Australasian Institute Mining and Metallurgy 266, 79-90 (June 1978). CALLEN R.A., 1975. FROME, South Australia, sheet SH54-10, 1:250 000 Geological Atlas Series. Geological Survey of South Australia. DE HAUTPICK, E. 1929. How radium occurs in nature. Elphick Dennis Print, South Australia 15pp. ELLIS G. K. 1980. Distribution and genesis of sedimentary uranium near Curnamona, Lake Frome region. South Australia. AAPG Bulletin 64, 1643-1657. HAYNES R.W. 1975. Beverley sedimentary uranium ore body, Frome Embayment, South Australia. In: Knight, C.L. (Ed.), Economic Geology of Australia and Papua New Guinea. Australasian Institute of Mining and Metallurgy. Monograph, 1, 808-813. JOHNS R.K. 1970. Mineral Developments Announced. Annual Report of the South Australian Department of Mines 1969-1970. p 51-53. LABYT.H.L. & MAWSON D. 1905. "Radium: How to explore for radium-bearing minerals" Daily Telegraph, Sydney (25 January 1905, page 9, column 5. SPRIGG R.C. 1984. Arkaroola - Mount Painter in the northern Flinders Ranges, S.A. The last billion years. Lutheran Publishing House 295pp. WHITTLE A.W.G. 1954 Radioactive minerals in South Australia. Bulletin Geological Survey of South Australia 20, 126-151.

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Sprigg Symposium, Adelaide, November 2007

IMPROVING THE RELIABILITY OF AU-IN-CALCRETE ANOMALIES THROUGH THE USE OF REGOLITHLANDFORM MAPPING AND DETAILED ASSAY ANALYSIS R.C. Dart, S.M. Hill, K.M. Barovich and D.J. Chlttleborough CRC for Landscape Environments & Mineral Exploration, The University of Adelaide, School of Earth and Environmental Sciences, North Terrace, Adelaide, South Australia, 5005

INTRODUCTION In the Gawler Craton, South Australia, numerous Au-in-calcrete anomalies have been identified; however, not all are located above mineralisation. Discovering a way of ranking these anomalies to improve their success rate is vital if the use of regolith carbonates (calcrete when indurated) in exploration is to become a more successful exploration tool. The Tunkillia Au deposit and the area towards the north was selected for this study due to the large Au-in-calcrete anomaly (--20 km^ at +10 ppb Au) over the area (Ferris and Wilson, 2004). Drilling has proven the existence of mineralisation below Au-in-calcrete anomalies at Tunkillia; however, anomalies located to the north of the area have no underlying mineralisation (van der Stelt et aL, 2006). This area therefore provides an ideal location to compare the differences in elemental dispersion, both over and away from underlying mineralisation.

METHODOLOGY Regolith carbonates were collected along 3 transects, selected to intercept known Au-incalcrete anomalies. The samples were assayed for a full suite of 53 elements. Regolith-landform mapping was completed along these transects and extended by interpretation of aerial photographs throughout the area to assist in determining potential drivers in the elemental distributions. The extent of the anomalous Au-in-calcrete area, approximate zones of known mineralisation and position of transects is shown in Figure 1. The aerial photography suggests that the anomaly may be following alluvial channels. Interpretation of assay data was completed using the software program ioGAS v2.1 (ioGlobal, 2007).

REGOLITH The regolith of the area can be divided into three distinct zones; a southern dune field, central erosional plain, and northern depositional

floodplain. The area north of the dune field is one of low relief with a slope of ~0.25% towards the north. Landforms and drainage patterns are partially controlled by this gentle slope resulting in small alluvial fans and a number of ephemeral lakes. The south of the area is dominated by large linear sand dunes. The dunes consist of redbrown (due to iron oxide cutans), medium size, and well sorted quartz grains. The dunes mark the eastern margin of the Great Victoria Desert which is gradually migrating eastwards and burying recent sediments as observed in the interdunal swales and sand plains. The swales consist of red-brown, iron oxide coated, fine to medium size, quartz sands that are moderate to well sorted. Larger interdunal plains are more dominant towards the north-eastern end of transect 1 (T1). These areas consist of redbrown, poor to moderately sorted, sub-rounded, fine to medium sized quartz sand with areas of higher clay and silt content. Cryptogams form a thin surface crust in many of these areas. Surface lag in this area is dominated by calcrete with areas of silcrete and occasional dolomite present. The interdunal plains reveal original surface features, including drainage channels and depressions. Three phases of dune development have been identified based on vegetation type and extent of cover (Lowrey, 2007). The central area consists of low relief erosional plains that are interspersed by numerous alluvial drainage depressions and minor channels (typically < 30 cm deep). The area is dominated by red-brown, poorly sorted, sub-rounded to sub-angular, fine to coarse quartz sand. Cryptogam surface mats are common. A dominant calcrete lag with occasional areas of silcrete lag covers most of the area. Shallow alluvial channels and depressions up to 1 m wide are typically very poorly sorted and have a higher clay, gravel, and pebble content than the surrounding areas. The northern area consists of numerous ephemeral lakes, drainage channels and

Geological Society of Australia Abstract No. 87

depressions, and occasion alluvial fans that are bounded by erosional plains. The erosional plains are similar to those in the central area. The flood plain area consists of fine sand, silt and clay. Mud cracks and cryptogam surface mats are common throughout the area. Numerous small shallow depressions up to 1 m wide lead into the lakes. The drainage depressions are similar to those described above. Calcareous surface material is present in places. The alluvial features of the central and northern areas appear as major features on the aerial photographs (Fig.1); however, their appearance on the ground is more subtle with the smaller drainage depressions being easily overlooked.

TRANSECT ASSAY RESULTS No single element was found to distinguish the zones of mineralisation alone; however distinct dispersion patterns were observed. Due to limitations in available space, the following is a summary of the more distinct observations with respect to assay results. Several elements have high concentrations over mineralisation (eastern end of T1) including: AI2O3, As, Au, Ba, CaO, Ce, Co, Cr, Cs, Cu, FezOa, Ga, Lu, MgO, Mo, Ni, P2O5, Pb, Rb, Sr, Th, Ti02, Tl, Tm, U, V, Yb, and Zn. Of these AI2O3, Au, Ba, Ce, Cr, Cs, Fe203, Ga, MgO, Mo, Rb, Th, Ti02, U, V and Zn are also high in the drainage channels and ephemeral lakes. Probability plots of the samples grouped by transect revealed distinct element distributions (Fig. 2). In a number of plots concentrations were lowest along T1; however, several of these showed a distinct rise at the end that often took the values above all others. These rises were typically related to the samples collected from over mineralisation. The T2 and T3 transects were similar for many of the elements with only minor variations in the plots. The rare earth elements had similar distributions with low values along T1 (apart from mineralisation) and higher, but equivalent values for T2 and T3. Strong correlations were observed for Au along T1 with Ni, CaO, MgO (+ve) and Si02 (-ve); however these correlations were not observed along T2 and T3. Elements that were strongly correlated along all three transects included: CaO & Si02, CaO & Sr, Ti02 & Fe203, and Ti02 & AI2O3. Most correlations were observed along T1 and T2. This suggests that T3 is located in a zone of ongoing transportation and movement compared to T1 and T2, which are located in zones of more settled material.

Sprigg Symposium, Adelaide, November 2007

DISCUSSION Through the use of regolith-landform mapping and detailed elemental assaying of samples it is possible to suggest preferential target areas. The increased concentrations of several elements along the central and northern transects supports a view that mobile elements are transported and accumulated in these areas. The distribution of Au is slightly offline of the current drainage. The low relief of the area and multiple drainage depressions suggest that the depressions and channels are in a state of continual migration and not permanent deep features of the landscape. The Au-in-calcrete anomaly also appears to follow palaeodrainage revealed from the interpretation of geophysical data (Lane and Worrall, 2002). Hence the Au is possible following a preferential drainage route rather than the current drainage. Observations of the aerial photograph would suggest that if the Au was mobilised along the drainage system it should also travel along the channel system located directly above mineralisation (Fig. 1). Closer inspection however, reveals that the dunes have buried channels that flow up to and possibly into the mineralisation zone. There is potentially a slight rise separating these drainage pathways. If mineralisation is situated to one side of this ridge then the preferential movement, either physically or chemically, will be towards the drainage system located down slope. The results presented here show that the collection of additional detail about the regolith at the time of sampling will assist in determining the relevance of the assay results. The data collected for this research are still being investigated, but it is expected that initial differences in elemental distributions between the three transects will be confirmed. This will then provide the basis of a model, which can be tested against other localities with the aim of identifying a definitive ranking system for Au-in-calcrete anomalies.

ACKNOWLEDGEMENTS Thanks are given to Tony Belperio, Richard Flint, and Barry van der Stelt of Minotaur Exploration for access to the research area and financial support. References FERRIS G. & WILSON M. 2004. Tunkillia Project; Proterozoic shear-zone-hosted gold mineralisation within the Yarlbrinda shear zone. MESA Journal 35, 6-12. lOGLOBAL. 2007. ioGAS Exploratory data analysis system [Computer program], Available from ioGlobal Pty Ltd. http://www.ioglobal.net, Perth. LANE R. & WORRALL L. 2002. Interpretation of airborne electromagnetic data: Summary report

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Geological Society of Australia Abstract No. 87

on the Tunkillia workshop, pp. 78. Geoscience Australia. LOWREY J. R. 2007. Plant biogeochemical expression of Au-mineralisation buried by an aeolian dunefield: Tunkillia, South Australia, p. 116. The University of Adelaide, Honours thesis (unpublished).

474000

VAN DER STELT B. J., BOUNDY M. & FLINT R. B. 2006. PACE initiative: Theme 2, year 2, drilling partnership - New Weil and Old Well shearassociated gold mineral prospects project final report, pp. 73. Department of Primary Industries and Resources. Open File Envelope 11,166, South Australia.

478000

480000

Figure 1. Aerial photograph of the research area showing the 3 transects, zones of mineralisation, and extent of Au-in-calcrete anomaly.

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Geological Society of Australia Abstract No. 87

CaO_pct

Au_ppm

• 1 75

-1.50

-1.25

-D.25

D DO 0 25 N score

Q 50

0.75

Fe203_pct

AI203_pct 4.25 4.00 3.75 3 .50 • 3.26 • 3.00 [ 2.75;

I 2.501

2^51 2.00!

2.0

# -1 75

-1 50

-1.25

-025

000 0.25 N score

050

1.25

1 50

1 75

2.00

-1.75

-1.50

-1.25

-1.00

-0.75

ODD 0 26 N score

D.50

0.75

1 00

1.25

Figure 2. Selected probability plots highlighting variations between the three transects: T1 - squares, T2 triangles and T3 - circles.

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Geological Society of Australia Abstract No. 87

INCORPORATING SURFICIAL GEOLOGY AND THE SEDIMENTARY RECORD INTO TECTONIC DRIVEN LANDSCAPE EVOLUTION MODELS J. E. Davey ^^^ and S. M. Hill ^ ^Australian School of Petroleum, Santos Petroleum Engineering Building, University of Adelaide, 5005 ^CRC for Landscape Environments and Mineral Exploration, School of Earth & Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005

INTRODUCTION The Mt Babbage and Mt Painter inliers in the northern Flinders Ranges provide an interesting paradigm of an ancient landscape preserved in a modern setting. Here, landforms of at least Mesozoic age coexist with active tectonism and extensive denudation. The complexity has proven to be a challenge in developing a complete longrange palaeogeographic evolution model. This highlights the need for a landscape analysis technique that can incorporate many different aspects of the contemporary landscape formation and the preserved geological record. Sedimentary basin formation and evolution involves a complex interaction of lithospheric deformation and surficial response. As well, postformation geomorphic evolution is often more readily recognised in basins by the disruption to patterns of basinal infilling sediments. As a result, basins have potential to preserve the record of a complex geological evolution. This study employs an analysis and interpretation of sediments on the southern margin of the Eromanga Basin, within the northern Flinders Ranges, to refine previous landscape evolution models. Ancient landforms and modern tectonism will be compared with data from previous studies to generate a relative evolution of the area to aid in the reconstruction of the geological and environmental history.

12 km fv<!t Painter Complex

•

Uf^Sylating plains & l-sw-l^lis

• gunpowder Bore iwatana

THE NORTHERN FLINDERS RANGES The northern Flinders Ranges form the northerly extent of the Adelaide Geosyncline, a discontinuous upland system extending 600 km from coastal to central South Australia. The northern Flinders Ranges is defined as the Mt Painter and Mt Babbage inliers (Fig. 1), and is largely incorporated within the area mapped on the South Australian 1 mile map sheet of Moolawatana. Broadly, this area can be divided into two geomorphic zones: the mountains and low hills that form the ranges (average elevations of 300-500 m); and the low-lying, undulating plains that form the surrounding basins (average

Figure 1. The Mt Babbage & Mt Painter inliers

elevations at or near sea-level). The bedrock in the area is comprised of Palaeoproterozoic Radium Creek Metamorphics; Mesoproterozoic granites and gneisses (including the Mt Neil Granite and Moolawatana Suite); and sediments and metasediments of the Neoproterozoic

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Geological Society of Australia Abstract No. 87

Adelaidean sequence (Sheard, 2001). These rocks are primarily exposed within the ranges, with sporadic sub-crop and tors throughout the basins. Lapping up onto, and overlying the bedrock are Mesozoic and Cainozoic sediments of the Eromanga and Lake Eyre basins respectively (Sheard, 2001). Eromanga Basin sediment exposures are predominantly, but not limited to the areas immediately flanking the inliers. The most common lithologies include coarse-grained, fluvial sandstones and conglomerates of the late-Jurassic Algebuckina Sandstone and early-Cretaceous Cadna-owie Formation; and shallow marine shales and mudstones of the Aptian to mid-Albian Bulldog Shale. These sediments cap some of the prominent uplifted landforms in the area, including Mt Babbage (Sheard, 2001; Quigley et a!., 2007). For the most part, the Cainozoic Lake Eyre Basin sediments overlie the Mesozoic sediments (Sheard, 2001). These are comprised of deposits within fluvial channels, fans and flood plains, as well as lacustrine sediments. Quaternary sediments cap many landforms in the basins, predominantly as either aeolian dunes or sheet flow deposits on the plains.

THE SOUTHERN EROMANGA BASIN Sediments from the southern margin of the Eromanga Basin form a significant component of the landscape in the northern Flinders Ranges. The sediments represent a time when Australia was rifting from Antarctica during the final stages of the separation of Gondwana (Veevers, 2006). Accompanying subsidence within central Australia resulted in the formation of the basin and subsequent sedimentation. Sediments within the basin include an initial fluvial and lacustrine regime followed by a marine incursion. A short hiatus in sedimentation occurred after the marine regression, which was followed by a reactivation of fluvial environments. The basinwide sediment nomenclature is shown Figure 2, together with the local nomenclature applied in the southern margin of the basin.

Cenomanian

Formation

Local

Winton Formation

Oodnadatta Formation Attraction Hill Sandstone Butldog Shale

PREVIOUS STUDIES

Early

Geomorphological studies in the northern Flinders Ranges have recognised ancient landforms preserved within the modern landscape (Twidale, 2000). Their contemporary existence has been attributed to the long-term relative inactivity and stability of inland Australia (Twidale, 1994; 2000). These studies have also recognised that the ranges, and associated numerous structural basins, sub-basins and troughs of various ages have contributed to the present day landscape. Recent contemporary stress and seismic analysis confirm that this is still a very seismically active region. The Flinders Ranges are considered to be one of the most tectonically active areas in Australia, registering more than 100 small earthquakes every year (Greenhaigh et a/., 1994). This has stimulated recent studies focusing on modern day relief features produced by up-lift rates of up to 160 m/Ma (Sandiford, 2003; Celerier et aL, 2005; Quigley et a!., 2006; Quigley et aL, 2007). Dating techniques such as Cosmogenic Nuclide Analysis (CAN) and Optical Stimulated Luminescence (OSL) have been used to establish length of surface exposure and erosion rates of fault scarps and pediments coupled with structural analysis (Sandiford, 2003; Quigley et al., 2007). These studies also favour an inactive 'peneplain' landscape in the area since the Delamerian (Celerier et al., 2005). The challenge is to incorporate, or reconcile both interpretations.

Subgroup

Aptian

Valangin

Cadna-owie Formation

Well Sandstone Pelican Well Forn^tion

lithonian Klmmeridgian Oxford Ian

Algebuckina Sandstone

Village Well Forrnation

Mid

Figure 2. Eromanga Basin stratigraphy

Sediment relationships between the Eromanga Basin and the local bedrock indicate that the landscape had both elevation and topographic variability prior to Mesozoic deposition i.e. was not a peneplain. Around Moolawatana (Fig. 1), shorelines of late Cadna-owie Formation to very early Bulldog Shale equivalents have been preserved flanking small granitic rises. These shorelines are identifiable by the presence of rounded and flattened 'beach' pebbles and shells. This relationship has been interpreted to have been formed in an archipelago during the early-Cretaceous in which the granitic rises were small islands in the early stages of the Eromanga Sea. Further supporting the concept that there was considerable elevation and topography in the pre-Mesozoic landscape in the area is the distribution of the Marree Subgroup, particularly

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Geological Society of Australia Abstract No. 87

different elevations including atop of Mt Babbage and throughout Prospect Hill. Extensive bevelled surfaces graded by the Eromanga Sea forming the lowest points of the landscape during the Mesozoic, are now elevated in the landscape (up to 300 m). The uplift of these landforms is poorly constrained, but primarily, although not exclusively associated with the faulting in Terrapinna Corridor.

the equivalents of the Bulldog Shale. Bulldog Shale sediments have an abrupt boundary at the Mt Painter Inlier margin in the north. Incised valleys associated with knick-point retreat have exposed profiles of the shales indicating that the sediments disconformably overly the granites and tillites in the area. These profiles also show that the thickness of the sediments in some places around the margin of the inlier exceeds 8m. However, exposures of the sediments are limited to the northern aspect of the inlier. This is interpreted as the Mt Painter Inlier having considerable relief at the time of sediment deposition. While active tectonism is evident along this fault-controlled-range and attributed to the uplift (Quigley et ai, 2007), the stepped expression of this range front and several knick points within valleys support reactivation of the fault, with the abrupt sediment margin suggesting it was active pre-Mesozoic. Exposures of fluvial sediments representing Mesozoic palaeodrainage systems are common throughout the south and north of the area. In the north, exposures of these sediments exceed 30m with variable palaeoflow directions indicating that they were meandering systems controlled by lithological variations in the bedrock. Many of these palaeodrainage systems correspond to modern exposures of faults, perhaps indicating that the faults were active and formed the valley systems that host the sediments. Considerable deformation was occurring throughout the mid-Mesozoic when the subsidence in central Australia led to the formation of the Eromanga Basin. This tectonism continued syn-deposition, as evidenced by angular unconformities between Parabarana Sandstone and the overlying Marree Sub-group. Near Pigeon Springs to the north of Mt Babbage (Fig. 1), the angular unconformity is up to 20 degrees in which the Parabarana Sandstone has been folded, but the overlying Bulldog Shale remains relatively undeformed. Uplifted Parabarana Sandstone and overturned Marree Subgroup sediments indicate that deformation continued post Mesozoic. In the Terrapinna Corridor, incised valleys expose profiles of overturned Mesozoic sediments that have been dragged up and over by faulting that controls the southern extent of the Mt Babbage Inlier. These exposures also show Cainozoic sediments from the Lake Eyre Basin that are flat lying and not affected by this faulting. This is indicative of the fault motion occurring pre Eocene, when the Lake Eyre sediments (namely Eyre Formation) were deposited, but post Mesozoic. Parabarana Sandstone remnants are common through out the Mt Babbage Inlier at

THE LAKE EYRE BASIN

The Lake Eyre Basin formed within the area during the Cainozoic, providing a further benchmark for the relative constraints on the landscape evolution model. Faulted fans and fluvial sediments from this basin constrain fault activation to post-Miocene (Quigley et ai, 2007). Sediments within this basin locally reflect the reworking of Mesozoic sediments from around the northern Flinders Ranges, highlighting the erosion of the sediments between the Mesozoic and Eocene. Quaternary sediments within the area have also been deformed, highlighting the youth of some of the tectonism.

LANDSCAPE EVOLUTION MODEL

This landscape evolution model is constructed using the Eromanga Basin sediments as a benchmark: • The pre-Mesozoic landscape consisted of low hills and rises in the Mt Babbage Inlier accompanied by mountains and hills in the Mt Painter Inlier. • Subsidence and tectonism in central Australia resulted in the formation of the Eromanga Basin. • The uplift in the northern Flinders Ranges formed the boundary of the Basin. • Tectonism occurred throughout the Mesozoic as represented in the various levels of deformation in the Eromanga sediments. • Post-Mesozoic but pre-Eocene faulting caused much of the uplift and defined the southern extent of the Mt Babbage Inlier. • Considerable erosion of Mesozoic sediments. • Subsidence resulting in the formation of the multiphase Lake Eyre Basin, locally sediments dominated by reworked Mesozoic sediments. • Continual tectonism and substantial erosion (Quigley et ai, 2007).

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Geological Society of Australia Abstract No. 87

CONCLUSION The Landscape of the northern Flinders Ranges has been evolving since at least the Mesozoic. Different stages of tectonism have accounted for the substantial uplift within the ranges and the presence of ancient landforms in the modern landscape. While recent active tectonisnn has played an important role in the uplift, sediments from the Eromanga Basin indicate that the preMesozoic, syn-Mesozoic and pre-Eocene uplift have all played a significant role in the uplift. Basin analysis as a means of interpreting hinterland landscape evolution is highly effective as basins preserve geological histories.

ACKNOWLEDGEMENTS CRC LEME and PIRSA's Pace Initiative are thanked for funding. Heathgate Resources are thanked for in-kind support. References CELERIER J, SANDIFORD M, LUNDBEK D, & QUIGLEY M. 2005. Modes of active intraplate deformation, Flinders Ranges, Australia. Tectonics 24.

GREENHALGH S.A, LOVE D, MALPAS K, & MCDOUGALL R. 1994. South Australian earthquakes, 1980-92. Australian Journal of Earth Sciences 41: 4 8 3 ^ 9 5 . QUIGLEY M, SANDIFORD M, & CUPPER M. 2006. Landscape expressions of late Quaternary climate change and large flood events. Flinders Ranges, South Australia. Geological Society of Australia 2006 Earth Sciences Convention Program With Abstracts. QUIGLEY M. SANDIFORD M. FIFIELD K. & ALIMANOVIC A. 2007, Bedrock erosion and relief production in the northern Flinders Ranges, Australia. Earth Surf. Process. Landforms 32, 929-944. SANDIFORD M. 2003. Neotectonics of southeastern Australia: linking the Quaternary faulting record with seismicity and in situ stress. In: Evolution and Dynamics of the Australian Plate, Hillis RR, Muller D (eds). Geological Society of Australia, Special Publication 22: 101-113. SHEARD M. J. 2001. Callabonna 1:250 000 geological map released. MESA Journal, 21: 27-29. TWIDALE C.R. 1994. Gondwanan (Late Jurassic and Cretaceous) palaeosurfaces of the Australian Craton. Palaeogeography, Palaeoclimatology, Palaeoecology 112:157-186. TWIDALE C.R. 2000. Early Mesozoic (?Triassic) landscapes in Australia: evidence, argument and implications. Journal of Geology lOS: 537-552.

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Geological Society of Australia Abstract No. 87

CONSTRAINTS ON THE FOUR MILE URANIUM MINERALISATION, RESULTING FROM NEO-TECTONIC ACTIVITY IN THE NORTHERN FLINDERS RANGES, SA. C.D. Dubieniecki and S.M. Hill School of Earth and Environmental Sciences, University of Adelaide, Australia, 5005

Paralana Fault, show exposures running through the northern Flinders Ranges further suggesting that the Flinders Ranges remain seismically active (Doyale et al., 1968; Hillis et al., 1999; Hillis etal., 2000; Reynolds etal., 2003)

INTRODUCTION

The northern Flinders Ranges and flanking plains (Fig. 1) host major occurrences of primary and secondary uranium mineralisation within the world-class Frome Embayment uranium province. To date, the largest known secondary mineralisation occurrence is the sedimentary (sandstone-type) mineralisation at Four-Mile Creek on the margins of the north-eastern Flinders Ranges. The development of secondary uranium mineralisation, such as at Four Mile Creek, is dependent upon a range of regolith and landform processes that influence the source, transport and accumulation of uranium within the regions history of landscape evolution. Tectonism has had a major influence on this regional evolution since the Flinders Ranges were first uplifted and is therefore very likely to have a major influence on the development of the Four Mile Creek uranium mineralisation. Due to the intra-continental setting of the Flinders Ranges, the recognition of the significance and timing of tectonic contributions to the landscape evolution has varied. Some previous research suggests that there is a lack of evidence to suggest recent tectonic activities have occurred, this in turn leads them to interpret that the tectonic activity that caused the uplift of the Ranges as being ancient, and possibly extending back as far or further than the Cainozoic (Veevers, 1984). Early research undertaken by Sprigg (1945, 1949); and later work by Williams (1973), Gallagher etal. (1994), Sandiford, (2003), Quigley et al. (2004), Celerier et al. (2005), Twidale and Campbell (2005), Quigley et al. (2007) and Wilson (2007) suggest that there is evidence that the contemporary topography results from post-Mesozoic events. The existence of basement rocks that have been thrust over Mesozoic and other unmetamorphosed sediments, as well as distinctive summit surfaces that have been locally overlain by Cretaceous fluvial sequences, agree with the suggestion that the major uplift causing the present day topography of the Flinders Ranges has occurred since the Mesozoic (Gallagher et al., 1994; Twidale and Campbell, 2005; Wilson, 2007). A number of active faults, most noticeably the

MINERALISATION Secondary uranium mineralisation is typically associated with roll-front systems. A roll-front system occurs when a primary source of uranium is modified, and primary uranium elements are mobilised by a mass transfer of groundwater which passes through reduced portions of regional aquifers generating geochemical trapping mechanisms (Hobday and Galloway, 1999). Many secondary uranium systems are sourced and concentrated within redox boundaries in remnant palaeodrainage and palaeovalley systems (Curtis ef al., 1990; Idnurm and Heinrich, 1993; Hobday and Galloway, 1999; and Wilson, 2007). Therefore, geomorphologic changes such as erosion, deposition and tectonism can create changes in relief, which affects transport gradients and dispersion. Such changes can also develop structural and stratigraphic chemical traps for the accumulation of uranium mineralisation. This suggests that by understanding the regolith-landforms (Fig. 2) and constraining surface expressions the impacts that neo-tectonics have had on the geomorphological evolution of a region, (in this study the northern Flinders Ranges) and in turn possibly the location and concentration of uranium mineralisation can be identified. The Mesozoic and Cainozoic range-front sediments along the margins of the north-eastern Flinders Ranges and the Frome Plains preserve evidence for palaeolandscape reconstruction that can be related to the sedimentary and postsedimentary evolution of secondary U mineralisation, particularly associated with the Eyre Formation hosted Four Mile mineralisation. The oldest sediments, exposed in fault-bounded rises in the area, are from the Mesozoic and are most likely equivalents of the Algebuckina Sandstone. They are dominated by locally derived granitic detritus, suggesting that the area presently occupied by the Flinders Ranges

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Geological Society of Australia Abstract No. 87

supported moderate relief and bedrock exposure at the time of sedimentation in the Mesozoic. The Mesozoic sediments are unconformably overlain by the Palaeogene Eyre Formation palaeodrainage sediments that display crossbedding indicative of a NW flow direction, along a highly weathered and topographically subdued range-front. Upper parts of the Eyre Formation sediments contain a pedogenic silcrete which is in turn overlain by fine sandy quartzose sediments that may be equivalent to the midTertiary Namba Formation. The Eyre Formation sediments, overlying silcrete and sediments (possibly equivalent to the Namba Formation), as well as the underlying Mesozoic sediments (Algebuckina Sandstone) display faulting, joints, and folding, which indicate that neo-tectonic activity has occurred post-deposition (Fig. 3). The same neo-tectonic events have restricted the preservation of post-Mesozoic sediments, including the U ore-bearing Namba Formation and Eyre Formation, and hence constraining the extent of the Four Mile U mineralisation along the Flinders Ranges, range-front.

ACKNOWLEDGEMENTS I thank CRC LEME, and PIRSA's PACE program for funding the project. PIRSA, in particular Steve More, for help in the field and in the office by providing maps and other data where needed. Heathgate Resources also provided in-kind support including meals and accommodation at the exploration camp. Heathgate Resources Ltd with Quasar, in particular Jess Oram, for knowledge of the area, allowing use of the lease, roads, accommodation and other facilities when in the field, and all CRC LEME post-graduate students for their help throughout the year. References CELERIER J. 2005. An excursion guide to the Flinders Ranges, South Australia; Neotectonics along the Paralana escarpment. Journal of Virtual Explorer.

20.

CURTIS J. L., BRUNT D. A. & BINKS P. J. 1990. Tertiary Palaeochannel Uranium Deposits of South Australia. In: Hughes F. E. ed. Geology of the Mineral Deposits of Australia and Papua New Guinea, pp. 1631-1636. Australasian Institute of Mining and Metallurgy, Monograph, 14. DOYLE H. A , EVERINGHAM I.B. & SUTTON D.J. 1968. Seismicity of the Australian continent. Journal of the Geological Society of Australia. 15, 295-312. GALLAGHER K., DUNITRU T. & GLEADOW A. 1994. Constraints on the vertical motion of eastern Australia during the Mesozoic. Basin Research. 6, 77-94.

HILLIS R.R., ENEVER J.R. & REYNOLDS S.D. 1999. In situ stress field of eastern Australia. Australian Journal of Earth Sciences. 46, 813-825. HILLIS R.R. & REYNOLDS S.D. 2000. The Australian Stress Map. Journal of the Geological Society, London, 157, 915-921. HOBDAY D.K. & GALLOWAY W.E. 1999. Groundwater processes and sedimentary uranium deposits. Hydrogeology Journal 7, 127138. IDNURM M. & HEINRICH C. A. 1993. A palaeomagnetic study of hydrothermal activity and uranium mineralisation at Mt Painter, South Australia. Australian Journal of Earth Sciences 40, 87-101. QUIGLEY M.C, SANDIFORD M., CUPPER M. & ALIMANOVIC A. 2004. Quantifying South Australian landscape evolution. Geological Society of America Abstracts with Programs 36 (5), 306. QUIGLEY M., SANDIFORD M., FIFIELD K & ALIMANOVIC A. 2007. Bedrock erosion and relief production in the northern Flinders Ranges, Australia. Earth Surface Processes and Landforms 32, 929-924. REYNOLDS S.D., COBLENTZ D.D. & HILLIS R. R. 2003. Influences of plate-boundary forces on the regional intraplate stress field of continental Australia. Geological Society of America Special Paper 372, 59-70 SANDIFORD M. 2003. Neotectonics of southeastern Australia: linking the Quaternary faulting record with seismicity and in situ stress. In: Hillis R. R. & Muller R. D. eds. Evolution and Dynamics of the Australian Plate, pp. 107-119. Geological Society of Australia, Special Publication 23. SPRIGG R.C. 1945. Some aspects of the geomorphology of a portion of the Mount Lofty Ranges. Transactions of the Royal Society of South Australia. 69, 277-304. SPRIGG R. C. 1949. Thrust structures of the Witchelina area, South Australia. Transactions of the Royal Society of South Australia. 73: 40-47. TAN K. P., DE CARITAT P., SCOTT K. M., EGGLETON R. A , SKIDMORE C. & LAWIE D. 2005. Portia north Portia Cu-Au-Mo prospects, South Australia. Regolith expression of Australian ore systems, (CRC LEME Perth), 386388. TWIDALE C. R. & CAMPBELL E. M. 2005. Australian Landforms; Understanding a low, flat, arid, and old landscape. Rosenburg Publishing, 336pp. VEEVERS J. J. 1984. Phanerozoic Earth History of Australia. Clarendon Press 418pp. WILLIAMS G. 1973. Late Quaternary piedmont sedimentation, soil formation and palaeoclimates in arid South Australia. Zeitschrift fur Geomorphologie. 17, 102-125. WILSON R. L. 2007. Palaeodrainage reconstruction at The Pimples', west of Mt Neil, Northern Flinders Ranges: Implications for uranium mineralisation and exploration. Unpublished Honours manuscript.

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365000

6665000

seemoQ

50QQm Figure 1. Location of the field area in relation to the Beverley Uranium deposit and Flinders Ranges; and (insert) Location of Flinders Ranges within Australia.

FOUR MILE CATCHMENT - NORTHERN FLINDERS RANGES 1:20 000 REGOLITH-LANDFORM MAP 354000

355000

356000

357000

358000mE

6661000 mN

Figure 2. 1:20 000 Regolith Land-form map of the Four Mile Catchment, Northern Flinders Ranges, SA. (N.B. scaled down, not 1: 20 000)

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Geological Society of Australia Abstract No. 87

UplSfted M e s o z o f c i e d J i n e m s

S e d U n e n t a r y m a p p t n g , dJsptays n o r m a t f a u l t s

Figure 3. 3D block model of the 'Forebergs', flower structure within the mapping area, and shows the general drainage of the catchment, along with the Range-front fault displacing sediments, as well as faults which uplift Mesozoic sediments.

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SURFACE GEOCHEMICAL EXPRESSION OF BEDROCK BENEATH THICK SEDIMENT COVER, CURNAMONA PROVINCE, SOUTH AUSTRALIA A J . Fabris' J.L. Keeling^ and R.W. Fidlei^ ^ CRC LEME/PIRSA, PO Box 1671 Adelaide, South Australia, 5001 ^ PIRSA, PO Box 1671 Adelaide, South Australia, 5001

electrode pairs connected to a disposable 9 volt battery. The electrodes were buried at around 0.25 m depth and 0.6 m apart, the area moistened by the addition of 1 litre of 30% HNO3, and then covered over by soil. These were left for around 48 hours after which time the electrodes were exhumed. The object is to collect mobile ions emanating from an ore body and to sample from a larger volume than might be feasible with traditional soil sampling methods.

INTRODUCTION Thick and highly conductive sediment cover impedes exploration in some of the most prospective areas of the Proterozoic Curnamona Province (Godsmark et al, 2003). Studies looking at the effectiveness of geochemical techniques in areas of thick cover have shown encouraging results (e.g. Kelley et al, 2003; Smee, 1998; Hamilton, 1998). To investigate the effectiveness of sensitive geochemical methods in the Curnamona Province, orientation surveys were undertaken over several prospects including Kalkaroo and Polygonum (described in this paper). These prospects were chosen due to prior geochemical experimentation and some degree of success (Law, 2003; Leyh and Corbett, 2001; Hedger and Dugmore, 2001). The approach was to focus on the use of partial extractants. These are designed to target loosely bound ions on the surface of mineral grains and therefore increase exotic metal ion contribution that may reflect underlying mineralisation and limit the contribution of the transported regolith components that are not related to mineralisation.

REGOLITH HISTORY Basement to the Curnamona Province consists of metasedimentary and metavolcanic Palaeoproterozoic rocks (Willyama Supergroup) and Mesoproterozoic intrusives. These are partially overlain by Neoproterozoic, Cambrian and Mesozoic marine sediments. A complex history of weathering and erosion at the end of the Mesozoic and extending into the Tertiary resulted in deep weathering and the removal of cover in uplifted areas. Fluvial and lacustrine sedimentation dominated through the Palaeogene. Together with Neogene alluvial and aeolian sediments, these form a sediment blanket ranging from a few metres close to the ranges to 250 m thickness in the north-west of the province. Alluvial and to a lesser extent colluvial processes currently dominate surficial sedimentation in the Kalkaroo region. The Polygonum Prospect area is dominated by colluvial and aeolian regolith-landform features where sheet flow is the dominant mode of sediment transport

METHODS Four, 500 m lines were surveyed at the Kalkaroo Deposit and sampled at 20 m spacing (104 sample sites). A 3.5 km survey line was positioned at the Polygonum Prospect involving 71 sample sites (50 m spacing). At both prospects, samples were collected from 10-25 cm and from the zone of high soil moisture loss as indicated by the presence of secondary calcium carbonate and sulphate (60300 cm). Samples were treated using aqua regia and the partial extractants, weak cyanide, sodium hydroxide, magnesium chloride and the proprietary method MMI-M. Conductivity and pH measurements were made on all samples. A Chinese variant of the electrochemical CHIM technique was also trialled over two profiles at the Kalkaroo Deposit. The setup of the 'Chinese CHIM' comprised specially coated carbon

GEOCHEMICAL SURVEYS Kalkaroo Cu-Au-Mo Deposit Mineralisation being targeted on each traverse has been located from approximately 110 m below the surface and beneath 35-70 m of transported regolith with decreasing cover thickness from Line A to D. There were no multi-point anomalies directly over mineralisation. However, over 3 survey lines and using most partial leach techniques, double-

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Geological Society of Australia Abstract No. 87

peak ('rabbit ear') anomalies for Mo, and occasionally evident in U, Au, Cu and conductivity measurements, were evident that corresponded with the margins of the strata hosting mineralisation. Plots of data for Mo display this trend (Figure 1). In the two profiles where the electrochemical CHIM technique was trialled, either high contrast, one point anomalies were observed over mineralisation or broad but barely anomalous responses were seen. The subsurface distribution of some bedrock units was recognisable from the data. On Lines B and C, a distinct Ag±As response over hanging wall strata is evident in partial leach results from 10-25 cm depth samples.

Polygonum Multi-element Prospect Low-grade mineralisation is known from 200-600 m depth and below 100 m of transported sediments. Mineralisation has been intersected in a range of stratigraphic levels leading to the targeting of at least 4 separate and adjacent prospective stratiform to stratabound zones. These are: 1. 'Stratiform' Cu-Au-Mo, 2. Stratiform to stratabound Zn-Pb-Ag (Mn, W, Mo, As, Co, Cu), 3. Broken Hill-type (BHT) Pb-Zn-Ag, 4. McArthur River Zn-Ag-Pb (Cu). Broad, multi-element anomalies were evident over McArthur River and stratiform/ stratabound-style Zn-Pb-Ag mineralisation although in the case of the McArthur River-style mineralisation, the extent and significance of underlying mineralisation has yet to be determined. While less clear, particular units, though not necessarily anomalous, are recognisable from their Ag content.

Sample Depth A choice of what depth interval to sample in a soil profile is one of the first problems faced when conducting a geochemical survey. In arid areas where no appreciable A-horizon is formed it can be quite difficult to distinguish features in the profile that mark preferential sites for sampling. The effect of capillary rise and evaporation are believed to concentrate solutes from approximately 10 cm below the surface and be an ideal interval for partial leach geochemical sampling (Mann et ai, 2005). This sample interval was one of two used in this study. Recent work within CRC LEME has shown that metal ions can be preferentially at the top of regolith carbonate horizons (McQueen & Khider, 2007; Dart et ai, 2006). In the arid environments of southern Australia it is common to identify regolith carbonate by reaction to acid (10% HCI). For this survey, the first appearance of carbonate or gypsum nodules was used as the sampling criteria for the second sample interval. While showing an elevated Ag response above hanging wall strata, samples taken from the deeper interval failed to show any response to mineralisation in geochemical profiles across the Kalkaroo Prospect. In contrast, although not totally consistent, analysis of surficial samples gave a response to mineralisation, particularly Mo (Fig. 1) but also Cu, Au and U. Both sample intervals gave a response over buried mineralised bedrock at the Polygonum Prospect. However, the response was different for each in terms of element distribution and intensity. This suggests differences in processes of metal ion concentration within the regolith profile.

CONCLUSIONS Geochemical surveys were conducted over mineralisation in the Curnamona Province to determine whether specific partial leach methods could be usefully incorporated into future mineral exploration programs in the region. Given the thickness of transported cover, which includes substantial thicknesses of lacustrine clay of low permeability, a simple definitive response over mineralisation was unlikely. Although no technique trialed in this study can be regarded as necesarily a highly reliable exploration tool, survey results demonstrate that the geochemistry of surficial soils appear to reflect elements of mineralisation and/or underlying basement geology through as much as 100m of transported cover.

DISCUSSION Comparison of Techniques Of the techniques used, partial leaches consistently produced clearer anomalies when compared with the results from a strong acid (aqua regia) digest, although some anomalies were unrelated to known mineralisation. Of the partial leaches, weak cyanide gave the most consistent results. CHIM provided a surface response in orerelated elements at Kalkaroo that best correlated with highest-grade mineralisation at depth. The anomalies were mostly single elevated values. Soil sampling produced quite different results to those using CHIM, which suggests a fundamental difference in ion liberation and collection between the two methods.

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Acknowledgements

HEDGER, D. & DUGMORE, M., 2001. Geochemical Detection of Deeply Buried Mineralization Below the Mundi Mundi Plain, Curnamona Province Implications for Discovery Success. MESA Journal 2^, 50-51. KELLEY, D.L., HALL, G.E.M., CLOSS, G.L., HAMILTON, I.e. & MCEWEN, R.M. 2003. The use of partial extraction geochemistry for copper exploration in northern Chile. Geochemistry: Exploration, Environment, Analysis, 3, 85-104. LAW, S.R. 2003. M.I.M. Exploration Pty Ltd Technical Report No. 3308 - EL 2720 "Kalkaroo" Annual Report for the year ending 9th May 2003. Unpublished confidential envelope. LEYH, W. & CORBETT, W. 2001. Joint annual report for EL 4656 and 4657 "Mundi Mundi" for the period 21 April 2000 to 20 April 2001. Volume 1 of 1. Platsearch NL, Inco Limited. Unpublished confidential envelope. MANN, A.W., BIRREL, R.D., FEDIKOW, M.A.F. & DE SOUZA, H.A.F. 2005. Vertical ionic migration: mechanisms, soil anomalies, and sampling depth for mineral exploration. In: Geochemistry, Exploration, Environment, Analysis, 5, 201-210. MCQUEEN, K. & KHIDER, K. 2007. Gold dispersion in the calcrete zone, Girilambone region, western New South Wales, Australia. In: Perez, J.L. eds. lAGS 2007 - Exploring our Environment; Program and abstracts of the Syposium. Oviedo, Spain, 185. SMEE, B.W. 1998. A new theory to explain the formation of soil geochemical responses over deeply covered gold mineralisation in arid environments. Journal of Geochemical Exploration, 61, 149-172.

Data presented here are from a 3-year collaborative project to examine the effectiveness of geochemical methods in the Curnamona Province. The project is supported through the Cooperative Research Centre for Landscape, Environments and Mineral Exploration (CRC LEME). Colleagues from CRC LEME involved in the project are acknowledged for advice and constructive discussions. Havilah Resources NL and Platsearch NL provided generous access to data held in confidential files. References DART. R.C, CHITTLEBOROUGH, D.L. & BAROVICH, K.M. 2006. Gold distribution through the regolith profile: examples from the White Dam Prospect, Olary, South Australia. In: Fitzpatrick, R.W. & Shand, P. eds. Regolith 2006 - Consolidation and Dispersion of Ideas, CRC LEME, Perth, Western Australia, 48-52. GODSMARK, B., HUDSON, M., HUGHES, N., MCINNES, D. & TEALE, G. 2003. Geophysical exploration for copper-gold mineralisation in the Benagerie Ridge Magnetic Complex, Curnamona Province, South Australia. In: Denith, M.C. ed. Geophysical signatures of South Australian mineral deposits, Perth Western Australia, 135146. HAMILTON, S.M. 1998. Electrochemical masstransport in overburden: a new model to account for the formation of selective leach geochemical anomalies in glacial terrain. Journal of Geochemical Exploration, 63, 155-172.

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LINE A

LINEB

LINEC

200 300 Metres

400

500

Figure 1. Plots of Mo response over Line A, B and C at the Kalkaroo Deposit (10-25 cm depth samples). All weak partial leach methods show elevated levels of Mo on the margin of the unit hosting mineralisation. The area directly above mineralisation is highlighted in each plot by a hatched column.

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REDUCE, REUSE, RECYCLE: THE GAWLER CALCRETE REANALYSIS PROJECT R. Fidler Geological Survey, PIRSA, GPO Box 1671, Adelaide, Australia, 5001

though several projects and on the way acquired as many as five analytical batch numbers! From a brief inspection of the pulps, it was expected that there would be something like 130gms of material available for each sample except for those samples that had been used for supplementary test work. Since it was desirable that there be lOOgms of sample remaining for the future, the aim was to consume no more than 30gms in this exercise, and preferably less. This is not particularly challenging for most modern methods but in combination with a large, element list, does put a limit on the number of methods that can sensibly be used and a premium on versatility. While compatibility with existing data was desirable for comparative purposes, the diversity of methods used by the original collectors of the samples limited how far this could be taken. For the most commonly determined element, gold, for instance, several acid extraction techniques coupled with a variety of instruments had been used, a number of fire assay methods, also BLEGs and several partial leaches (unusual with samples pulverised to <75|im). Even then, the analytical techniques used were not necessarily known for every sample but most seemed to have been analysed using an aqua regia leach followed by some form of instrumental estimation. For older data, this tended to be graphite furnace AAS while more recent results were obtained with ICPMS. An aqua regia attack is a good choice for gold exploration because it ensures the dissolution of gold (and silver) and there is no risk of calcium fluoride precipitation potentially possible with some multi-acid attacks. Another method of interest was X-ray fluorescence (XRF). Much of the current interest in the Gawler Craton area is in uranium exploration and there is a tendency for uranium explorers to prefer X-ray fluorescence methods. XRF is a particularly reliable but not, by modern standards, a sensitive method being mainly used for heavy elements expected in the ppm to low percent range. The detection limit for uranium is about 5ppm, or a little better with extended counting time. While this is generally considered sufficient for exploration purposes, the average crustal abundance of uranium is reckoned at only

INTRODUCTION The nature of exploration often favours a one-use approach but occasionally, an opportunity to use samples more than once, arises. Such was the case when a consignment of exploration samples, scheduled for disposal, was acquired by PIRSA. The samples were laboratory surpluses of various kinds, largely originating from Gawler Craton gold exploration programmes. In excess of sixty pallets of these samples were assembled containing of the order of half a million samples. Of particular interest were the calcretes. Previously, a compilation of the analytical results from some 165,046 calcrete samples contributed either directly or indirectly, by twenty four companies and supplemented with some additional analyses, by PIRSA, had been distributed. This had been well received but since the results had originated from gold exploration, the choice and range of elements used reflected this. So although all had been analysed for gold and many for copper, relatively few had been analysed for any other element and significantly in the present climate, none at all for uranium. This laboratory surplus material thus represented an opportunity to greatly broaden and improve the quality of the exploration information from the Gawler Craton at a relatively low cost and it was therefore decided to move to a "demonstration of concept" stage.

ORIENTATION Since the samples were already in hand, geochemical orientation of a traditional nature was not required but there were a large number of matters to be resolved before analytical work could begin. The first real challenge was to differentiate calcrete samples from the numerous drilling and general exploration samples that were on the sixty odd pallets and from them, ascertain which came from accurately positioned sample points. Due to the large number of samples involved, the selection process was fairly time consuming but also surprisingly complex since there were a variety of origins and consequently, sample numbers were not necessarily unique. Also some samples passed

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about 3ppm. When used with a pressed powder sample, XRF has the advantage of not requiring the sample to be dissolved albeit, at the cost of relatively high sample consumption. No analytical scheme is universally satisfactory for all elements that might be sought in the Gawler Craton. However, inductively coupled plasma mass spectrometry (ICPMS) is applicable to most of the economically interesting metals (such as nickel, uranium) and is also sufficiently sensitive to measure both the rarer, pathfinder elements (such as Se) and precious metals. Though generally less sensitive, inductively coupled plasma optical emission spectrometry (ICPOES) is also considered a convenient method for elements such as iron or calcium which are present in larger amounts and for a few elements, like vanadium or zinc which are not easily done by ICPMS. Since they can share the same leach solution, the combination ICPMS/ICPOES/aqua regia was considered the most satisfactory compromise for the calcretes. Currently, a scheme of thirty two elements: gold, copper, nickel, uranium, vanadium, arsenic, silver, bismuth, calcium, cadmium, cobalt, chromium, iron, gallium, magnesium, molybdenum, phosphorus, lead, platinum, antimony, selenium, tellurium, thorium, thallium, tungsten, zinc, cerium, lanthanum, rubidium, potassium and aluminium, is being used. Originally, a somewhat smaller suite of elements had been chosen based in part on a standard PIRSA scheme supplemented with elements indicated informally by members of the exploration community to be of interest (plus a number that were part of "the package" offered by the laboratory). However, representations were made to PIRSA for some further additions after the "proof of concept" stage had been completed, which resulted in the current thirtytwo element suite given above. The tender documents for a "proof of concept stage" program consisting of approximately 3000 samples were circulated to six laboratories and replies received. Amdel was ultimately awarded the contract. Excluding various repeats and quality control samples, 2,505 samples were processed in the "proof of concept stage" and the results released, in December, 2006. Some preliminary processing of this data has been carried out and will be discussed later but as a consequence of this work, it was decided to move on to the next, larger block of samples.

of consequence, it differed from the "proof of concept" stage principally in the scale of the exercise and by the addition of four elements to the analytical scheme. At a practical level, the large number of batches (35) meant maintaining quality control was more important than usual. Obtaining suitable standards, while difficult, is essential. Natural standards with analytically useful levels of all thirty two elements concerned do not exist but duplicates of samples previously analysed in the "proof of concept stage" were a reasonable substitute in that they provided similar, analysed material with similar levels for at least the elements of interest. Quality control was based largely on the repetitive use of these duplicate samples. Excluding quality control samples, approximately 10,500 samples are being analysed in this part of the programme, bringing the total to this point in the Gawler Craton Calcrete Reanalysis Program to about 13,000 samples.

RESULTS As the project is only partially complete, no attempt has been made at a comprehensive statistical analysis, but there are a number of results arising from the "proof of concept stage" data which are worthy of comment. Given the sampling medium, it is surprising that there is substantial variation in calcium content. Until the analyses were complete, accepting the company's designation of a sample as a calcrete was necessary but since both the samplers and the methods used to collect the calcretes are more than usually varied, the concept of calcrete was also likely to be variably interpreted. With this in mind, calcium analyses were included to allow users of the results to normalise their results, if they wished but also to allow them to set their own limits on what they regard as a "calcrete". A cumulative frequency plot of calcium results show there is a very distinct population of samples above about 15% Ca (calcretes) separated from an equally distinct population of what are presumably, calcareous soils (Fig. 1). The point of interest is that 20% of samples designated calcretes have less than 5% calcium (or 12.5% calcium carbonate) as shown by the arrow and line. Whether or not these samples are less effective as an exploration medium as a consequence remains to be determined. Although not determined initially, aluminium has been included in the current suite of elements. This gives a means of inferring the presence of aluminous clays and thus additional

MAIN PROGRAMME Although numerous refinements were introduced into the sample handling and related procedures for the main programme that followed, in matters

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The association between elements also held some surprises. While the association between gold and calcium was not obvious, the quality of the link between copper and magnesium was stronger than might have been expected (Fig. 3).

information as to the probable makeup of the lowcalcium samples. 100 50 20 10 5 2 g 1 ' o 0.5 U 0.2 0.1 0.05 0.02 0.01

i| ii|iii»| I I I iMMinttTTTrrmtprtrTm

99.99 99.8

Cumulative Frequency, per cent

| i |iiit|ii |i pn\i

0.2

0.01

Similarly, vanadium, an element of interest in connection with calcrete accumulations of uranium (as carnotite), shows an as yet unexplained close association with another radioactive element, thorium (Fig. 4). 30

m|iiii|mi|iiii|iiii|ii I 70 50 30

<111111

0.5

r-imrTTT

Cumulative Frequency, per cent

0.1

120

Figure 3. Mg (%) vs. Cu (ppm)

As the samples were largely collected in the search for gold, it is not surprising that the cumulative frequency plot for gold (Fig. 2) shows a very distinct, upper population that is undoubtedly anomalous, above about 60ppb. It remains to be seen what subtleties emerge with the full data set. Other elements having similar, clearly anomalous populations include copper, arsenic and bismuth. 1000 1 500 : 200 100 : a 50 j 20 'o 10 : O 5 i 21 1 0.5 = 90

Cu ppm

Figure 1. Cumulative frequency plot of Ca percent

100

200

Vppm

300

400

Figure 4. Th (ppm) vs. V (ppm) Other elements show a more complex but equally intriguing association such as this between molybdenum and chromium (Fig. 5).

0.01

Figure 2. Cumulative frequency plot of Au ppb

20 n

Chromium is not a particularly rare element with an average crustal abundance of a little over lOOppm. However the most common chromium mineral, chromite, does not easily break down nor does it readily dissolve in aqua regia. So even if present in the underlying rocks in appreciable amounts, it was not expected to feature strongly in the calcrete results. It was surprising therefore, to see quite a few results in excess of lOOppm. While chromium levels are of particular interest in the search for the element in its own right and also for platinoid metals, generally speaking, its value is as an indicator of mafic and ultramafic rocks and thus as an aid to geological mapping.

100

200

Cr ppm

300

400

Figure 5. Mo (ppm) vs. Cr (ppm) The significance of the very large number of associations possible is currently under review.

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Geological Society of Australia Abstract No. 87

URANIUM MINERALISATION EXPRESSION AND DISPERSION IN THE REGOLITH CARBONATE-BEDROCKPLANT SYSTEM NEAR THE FOUR MILE WEST URANIUM PROSPECT D. J. Gallasch and S. M. Hill CRC LEME, School of Earth & Environmental Sciences, University of Adelaide, South Australia, 5005

Anand et al., 1997; Hill et al., 1999; McQueen, 2006). The chemical relationships of regolith carbonates with chemical transport and cycling pathways and processes are also not clearly understood. Carlisle (1983) describes how the chemical sources of non-pedogenic carbonates, associated with U deposits, are derived from a large area of weathering rocks and regolith, while he interprets pedogenic carbonates to be derived from soil, dust and organic debris. Particular uncertainties also exist in the role that biogenic cycling within plants has on the cycling of various elements associated with regolith carbonates. The biogenic cycling of plants has been suggested to play an important role in mobilising elements, such as Au and Ca, from underlying soils and bedrock, enabling them to become available for incorporation into regolith carbonate deposits (Lintern, 1989; Lintern et al., 2006). The depth from which these chemical constituents are sourced depends on the plant root depth, which in arid environments can extend tens of metres (e.g. Canadell etal., 1996; Hulme and Hill, 2005). These deep-rooted plants could potentially lead to the chemical constituents of regolith carbonates being transported from depth, by processes such as 'hydraulic lift' (e.g. Canadell et al., 1996; Horton and Hart, 1998), and forming carbonate accumulations at shallower soil depths. Rose etal. (1979, in Dunn, 1983) explain how loosely bound U in sediments could be dissolved as a result of the low pH conditions around the roots of trees. This U is then readily available to be taken up by the plant and precipitated within the leaves due to changes in pH conditions. Redox changes associated with the rhizosphere would also presumably influence U mobility and uptake. An understanding of the origins of trace elements in regolith carbonates is of major economic importance to mineral exploration programs, particularly for uranium (e.g. carnotite mineralisation) and gold exploration. The use of pedogenic carbonates for Au exploration has been widely adopted in southern Australia (e.g.

INTRODUCTION Regolith carbonates are a widespread and abundant component of the regolith throughout semi-arid Australia (Goudie, 1983; Chen et al., 2002). Although they have been widely examined, some uncertainties still exist as to their chemical relationships with other landscape attributes, such as: potential chemical sources, including weathered bedrock and meteoric inputs; chemical transport and cycling pathways and processes, such as biogenic cycling within plants (e.g. Carlisle, 1983; Lintern, 1989; Lintern et al., 2006); and, their application and related mechanistic processes for geochemical mineral exploration programs. The chemical origins of regolith carbonates, including the source of major cations (e.g. Ca and Sr), but also the sources of trace elements (such as trace metals and U), are not clearly understood. Potential sources include: • bedrock weathering (e.g. Wang et al., 1994; Anand et al., 1997; Durand et al., 2006; Dart et a/., 2007); • aeolian accessions (e.g. dust) and rainfall (e.g. Quade et al., 1995; Capo and Chadwick, 1999; Hill etal., 1999; Lintern et

al., 2006); •

transported regolith weathering, such as pre-existing, re-worked pedogenic carbonates (e.g. Naiman et al., 2000; Van der Hoven and Quade, 2002); and, • biological cycling of plant matter (e.g. Hamidi et al., 2001; Tandon and Andrews, 2001). In southern, semi-arid Australia, techniques such as measuring the Sr-isotope attributes of regolith carbonates strongly suggest a prevailing meteoric (rainfall / aeolian dust) origin for the major cations, such as Ca (e.g. Quade et al., 1995; Capo and Chadwick, 1999; Dart et al., 2004; Lintern et al., 2006). This does not, however, satisfactorily account for recorded associations between particular bedrock lithologies (such as carbonate and mafic rocks) and the distribution of regolith carbonates (e.g.

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Geological Society of Australia Abstract No. 87

bedrock samples varies between below analytical detection to 52.5 ppm, with the elevated U assays occurring in two distinct regions (Fig. lb). The U assays are higher in the regolith carbonates than in the bedrock samples, as evidenced by the significant difference in U:Th ratios (averages of 4.55 and 0.30 respectively). This difference is apparent when U is plotted against Th for both media (Fig. 2). The regolith carbonate samples with low U assays plot in a similar region to that of the bedrock samples and reflect the low U:Th properties of bedrock. The regolith carbonates with high U assays, however, plot separately from where the majority of bedrock samples plot. These carbonates have high U:Th ratios, which indicates that some landscape fractionation of U and Th occurs, whereby Th becomes stabilised while U is mobilised and subsequently accumulated within the carbonates. The plant species, Eremophila freelingii (emubush), also shows variable U assays in the study catchment (0.01 to 0.40 ppm). The distribution of the high U assays in this species (Fig 1c), however, did not reflect the U distribution apparent in the regolith carbonates. The findings of the study have been used to develop a preliminary model for the source, mobilisation, accumulation and entrapment of U in regolith carbonates (Gallasch, 2007). This model includes: • a U source in a topographically elevated setting in the landscape (e.g. bedrockdominated ranges); • the mobilisation of U downslope, both physically (e.g. as colluvial material) and in solution; • the transportation of U-bearing groundwaters through the hydraulic lift of plants and the subsequent biogenic cycling of U in the leaf litter; and, • the accumulation / concentration of U in regolith carbonates in lower parts of the landscape (i.e. a low-lying U trap). An understanding of this model and the ability of regolith carbonates to accumulate U could provide the basis for U exploration programs utilising the widespread distribution of regolith carbonates throughout semi-arid Australia.

Lintern, 1989; Lintern et al., 2006). Lintern et al. (2006) suggest that locally derived Au is effectively hosted by regolith carbonates, mostly derived from exotic chemical sources (e.g. meteoric sources), as a result of mobile Au species undergoing, concurrently with calcite, repeated cycles of hydromorphic dissolution and precipitation. The formation of Au-in-calcrete anomalies has also been suggested to occur via microbial activity through the breakdown of urea (Schmitt Mumm and Reith, 2007), and by deeprooted plants drawing on Au-bearing groundwaters and depositing the Au at the surface through leaf fall and decomposition (Lintern, 1989). The use of pedogenic carbonates for the exploration of commodities other than Au is poorly understood. Carnotite-rich regolith carbonates have been used for U-related mineral exploration and in some regions may host Udeposits, such as at Yeelirrie, Western Australia (e.g. Mann and Deutscher, 1978; Carlisle, 1983). These regolith carbonates, however, are 'groundwater' or Valley' carbonates, and there have as yet been no recorded accounts of pedogenic carbonates being used in uranium exploration. The known occurrence of U-deposits within groundwater or valley carbonates indicates that carbonate-rich landscapes can be conducive to U precipitation. Whether the mechanisms involved in the precipitation of U in these groundwater carbonate environments could also, under the correct conditions, be utilised during the precipitation of pedogenic carbonates, is not known. This could have significant implications on the widespread use of pedogenic regolith carbonates as an important sampling medium for U exploration.

RESULTS AND CONCLUSIONS Regolith carbonates from a headwater tributary of the Four Mile Creek drainage basin, near the Four Mile West Uranium Prospect, contain variable U assays (1.0 - 244.0 ppm). The regolith carbonate samples with high U assays are limited to two regions in the catchment (Fig. la), which correspond to samples with high Ca assays. This is suggested to indicate that regolith carbonates with high Ca assays have better carbonate development and, therefore, act as a better U host. The range in U assays of associated

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Geological Society of Australia Abstract No. 87

Element Distribution Regolith Carbonate U(ppm) O

1.0-96.5

96.6-197.0

o O

197.1 - 2 4 4 . 0

Projected Mineralisation

255

Metres 510

GRID NORTH GDA 1994 (Zone 54)

Element Distribution Bedrock U (ppm) •

Below detection

0.6-21.5

21.6-43.5

43.6-52.5

Projected Mineralisation 255

353000

352000

353500

510

1,020

GRID NORTH GDA 1994 (Zone 54)

354000

§ Element Distribution I Eremophila freelingii U (ppm) 1

0.01 - 0.05

0.06 - 0.07

2 O (O

0.08-0.40

Projected Mineralisation

255

Metres 510

1.020

2 I I I « I I «—'—I

352000

352500

353500

GRID NORTH GDA 1994 (Zone 54)

Figure 1. Geochemical and biogeochemical maps of the U assays from the study catchment near the Four Mile West Uranium Prospect for the different sampling media, a) Regolith carbonate samples; b) Bedrock samples; c) Plant samples (Eremophila freelingii).

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Geological Society of Australia Abstract No. 87

Media Comparison of U vs Th (Four IVIile Catchment) 350 +

300 250 Th (ppm)

200 150

Th>U + +

o Carbonate

+ +

+ Bedrock

100 -

U >Th

50 OA

o o

9 50

100

0, 150

200

250

300

U(ppm)

Figure 2. Comparison of U versus Th between the different sampling media (regolith carbonates and bedrock). The carbonate samples plot as two discrete populations: the samples with Th > U reflect the low U:Th properties of bedrock; and, the samples with U > Th indicate some landscape fractionation of U and Th occurs, whereby Th becomes stabilised while U is mobilised and subsequently accumulated within the carbonates.

LEME Regional Regolith Symposia, pp. 67 - 70. CRC LEME, Perth. DUNN C.E. 1983. Uranium biogeochemistry of the NEA/IAEA Athabasca Test Area. In: Cameron E. M. ed. Uranium Exploration in Athabasca Basin, Saskatchewan, Canada, Paper 82-11, 127 132. Geological Survey of Canada. DURAND N., AHMAD S.M., HAMELIN B., GUNNELL Y. & CURMI P. 2006. Origin of Ca in South Indian calcretes developed on metamorphic rocks. Journal of Geochemical Exploration 88, 275 - 278. GALLASCH D.J. 2007. Regolith carbonate-bedrockplants: Trace element geochemical dispersion and hosts near the Four Mile West Uranium Prospect, South Australia. BSc Honours thesis. University of Adelaide, unpublished. GOUDIE A.S. 1983. Calcrete. In: Goudie A. S. & Pye K. eds. Chemical sediments and geomorphology: precipitates and residua in the near-surface environment, pp. 93 - 131. Academic Press, London. HAMIDI E.M., COLIN F., MICHARD A., BOULANGE B. & NAHON D. 2001. Isotopic tracers of the origin of Ca in a carbonate crust from the Middle Atlas, Morocco. Chemical Geology 176, 93 - 104. HILL S.M., MCQUEEN K.G. & FOSTER K.A. 1999. Regolith carbonate accumulations in western and central NSW: characteristics and potential as an exploration sampling medium. In: Taylor G. & Pain C. eds. Regolith '98: New Approaches to an Old Continent, Proceedings Volume, pp. 191 208, CRC LEME, Western Australia.

References ANAND R.R., PHANG C., WILDMAN J.E. & LINTERN M.J. 1997 Genesis of some calcretes in the southern Yilgarn Craton, Western Australia: Implications for mineral exploration. Australian Journal of Earth Sciences 44, 8 7 - 1 0 3 . CANADELL J.. JACKSON R.B., EHLERINGER J.R.. MOONEY H.A., SALA O.E. & SCHULZE E.D. 1996. Maximum rooting depth of vegetation types at the global scale. Oecologia 108, 583 595. CAPO R.C. & CHADWICK O.A. 1999. Sources of strontium and calcium in desert soil and calcrete. Earth and Planetary Science Letters 170, 61 72. CARLISLE D. 1983. Concentration of uranium and vanadium in calcretes and gypcretes. Geological Society, London, Special Publications 11, 185 195. CHEN X.Y., LINTERN M.J. & ROACH I.C. 2002. Calcrete: Characteristics, distribution and use in mineral exploration. CRC LEME, Perth 160 pp. DART R.C., BAROVICH K.M., CHITTLEBOROUGH D.J. & HILL S.M. 2007. Calcium in regolith carbonates of central and southern Australia: Its source and implications for the global carbon cycle. Palaeogeography, Palaeoclimatology, Palaeoecology 249, 322 - 334. DART R.C., WITTWER P.D., BAROVICH K.M., CHITTLEBOROUGH D. & HILL S.M. 2004. Strontium isotopes as an indicator of the source of calcium for regolith carbonates. In: Roach I.C. ed. Regolith 2004, Proceedings of the CRC

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Geological Society of Australia Abstract No. 87

NORTON J.L. & HART S.C. 1998. Hydraulic lift: a potentially important ecosystem process. Trends in Ecology and Evolution 13, 232 - 235. HULME K.A. & HILL S.M. 2005. River Red Gum biogeochemistry associations with substrate: bedrock penetrators or stream sediment amalgamators? In: Roach I. C. ed. Regolith 2005 - Ten Years of CRC LEME, pp. 146 - 151. CRC LEME. LINTERN M.J. 1989. Study of the distribution of gold in soils at Mt. Hope, Western Australia. CSIRO Australia. Division of Exploration Geoscience, Perth. Restricted Report 24R. CSIRO/AMIRA Project P241. Re-released as CRC LEME Perth Australia Open File Report 65. 36 pp. LINTERN M.J.. SHEARD M.J. & CHIVAS A.R. 2006. The source of pedogenic carbonate associated with gold-calcrete anomalies in the western Gawler Craton, South Australia. Chemical Geology 235, 299-324. MANN A.W. & DEUTSCHER R.L. 1978. Genesis principles for the precipitation of carnotite in calcrete drainages in Western Australia. Economic Geology 73, 1724 - 1737. MCQUEEN K.G. 2006. Calcrete geochemistry in the Cobar-Girilambone region. New South Wales. CRC LEME Open File Report 200, 27 pp. NAIMAN Z., QUADE J. & PATCHETT P.J. 2000. Isotopic evidence for eolian recycling of pedogenic carbonate and variations in carbonate dust sources throughout the southwest United States. Geochimica et Cosmochimica Acta 64, 3099-3109. QUADE J., CHIVAS A.R. & MCCULLOCH M.T. 1995. Strontium and carbon isotope tracers and the origins of soil carbonate in South Australia and Victoria. Palaeogeography, Palaeoclimatology, Palaeoecology 113, 103 - 117. SCHMIDT MUMM A. & REITH F. 2007. Biomediation of calcrete at the gold anomaly of the Barns prospect, Gawler Craton, South Australia. Journal of Geochemical Exploration 92, 13 - 33. TANDON S.K. & ANDREWS J.E. 2001. Lithofacies associations and stable isotopes of palustrine and calcrete carbonates: examples from an Indian Maastrichtian regolith. Sedimentology 48, 339 _ 355 VAN DER HOVEN S.J. & QUADE J. 2002. Tracing spatial and temporal variations in the sources of calcium in pedogenic carbonates in a semiarid environment. Geoderma 108, 259 - 276. WANG Y., NAHON D. & MERINO E. 1994. Dynamic model of the genesis of calcretes replacing silicate rocks in semi-arid regions. Geochimica et Cosmochimica Acta 58, 5131 - 5145.

ACKNOWLEDGEMENTS I am very grateful to CRC LEME (Curnamona Minex Project in program 1), PIRSA (PACE funding) and Quasar / Heathgate for funding this project. I would also like to thank Doug and Marg Sprigg and the management of Arkaroola Wilderness Sanctuary, and Jess Oram and Heathgate Resources Pty. Ltd. for facilitating access to field locations and for providing accommodation during the time spent in the field. A special thanks to Steve More from PIRSA for his help in the field and for sharing his unlimited knowledge of the region. I would sincerely like to thank the regolith research group from Adelaide University, in particular my superviser Steve Hill for his enthusiasm in the field and for his guidance and encouragement throughout the year. I would also like to thank Jessie Davey for her assistance during the year including with thin sectioning, Michael Neimanis for his background knowledge of the biogeochemistry of various plant species in the study region, Karen Hulme for her guidance with the plant sample preparation methods, and Robert Dart and Nathan Reid for their guidance and insight into the world of loGas and ArcGIS. Finally, my sincere thanks to my fellow Honours students, Michaela Jennings, Joanna McMahon, Andrew Hector and Clinton Dubieniecki, for their helpful discussions throughout the year and for their camaraderie during the many hours spent in the field.

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Geological Society of Australia Abstract No. 87

UPPER FOUR MILE CREEK PALAEOSEDIMENTS AND ASSOCIATED PALAEOLANDSCAPE RECONSTRUCTIONS, EROMANGA BASIN, NORTHERN FLINDERS RANGES, SOUTH AUSTRALIA A.N. Hector and S. M. Hill CRC LEME and Discipline of Geology & Geophysics, School of Earth & Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia

sections. This is particularly surprising given the close proximity of the sediment hosted Beverley Uranium Mine and Four Mile uranium mineralisation. This study shows that these sediment exposures contain key evidence for understanding the evolution and constraining the extent of mineralisation adjacent to the Four Mile U-mineralisation, as well as aspects of the postdepositional modification of the sediments due to tectonism, weathering and pedogenesis. The Four Mile mineralisation is at a depth of about 120 metres (Jess Oram, Heathgate Resources pers. com) of sediment, east of the range-front area. The rocks of the nearby mountain ranges - Gunsight and Radium Ridge contain exposures and sub-cropping extensions of primary (bedrock-hosted) U-mineralisation. The sediments along the range-front in the study area have been classified in some detail in the past where much of the area has been interpreted as part of the Eyre Formation. This is questionable as some sections clearly differ from the known Eyre Formation characteristics. The differences were identified by Callen (1981) and Sheard & Callen (2000) both mapping some Mesozoic sediments in the area. The uncertainty of the range front sediments classification proposed a problem to be addressed by this study and provides some validity for the study to go ahead. This study aims to describe and characterise the vertical exposures of the palaeosediments in the incised gullies along the range-front near Four Mile Creek. This will include logging of sections, palaeocurrent measurement, geochemical and thin section characterisation. The implications of this will then be considered for the evolution of the Four Mile mineral system and further regional exploration.

INTRODUCTION The study of paleosediments in Australia is important as it aids in the construction of genetic models that allow us to gain a greater understanding of ancient landscapes and how they have evolved over time. It provides valuable information for developing interpretive models relating to palaeogeography and palaeoenvironments as part of regional landscape evolution models. This study logs and characterises the Four Mile Creek sediments along with providing geochemical and thin section analysis. Stratigraphically these sediments are equivalent to the non-marine Algubuckina Sandstone, resulting in an age between Early Jurassic and Early Cretaceous. The observation of shallow palaeotroughs and cross bedding provide a North-South palaeoflow direction. Packages of upwards fining coarse pebbles are evidence of alternating wet and dry periods. Palaeosediments were deposited within a braided stream system. High values of uranium were associated with coarse-grained sands. Uranium correlates well with Th, Zr and Zn, therefore these elements may be good U-mineralisation pathfinders for future exploration in the area. The northern Flinders Ranges region is highly prospective for U-mineralisation. Major U resources are hosted in the palaeosediments associated with the flanking and overlying Tertiary and potentially the Mesozoic sedimentary basins. Understanding these sediments and associated palaeolandscapes has major economic implications for understanding the mineralisation as well as providing vectors and exploration models for discovering further mineralisation. Gully exposures along the northeastern Flinders Ranges range-front in the vicinity of Four Mile Creek show 3-dimensional profiles of palaeosediments; however, there are few published accounts of the detailed characteristics and associated palaeolandscape reconstruction derived from these sedimentary

PREVIOUS WORK Previous regolith and landscape evolution work in the Northern Flinders Ranges has been focussed on:

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Geological Society of Australia Abstract No. 87

• Observation and classification of some sediments (mainly grouped with the Eyre Formation and not in great detail). • The neotectonic evolution of the Northern Flinders Ranges.

The area is subject to an arid climate, with a median average rainfall of about 100 mm/year at elevation of 340 at nearby Arkaroola (Chambers, 2003).

Previous studies of palaeosediments along the north-eastern Flinders Ranges range-front have shown that ongoing tectonism throughout the Cainozoic has locally uplifted and exposed Cainozoic sediments of the Lake Eyre Basin and Mesozoic sediments of the Eromanga Basin (Coats and Blissett, 1971; Geological Survey South Australia, 1961). Along the range-front near Four Mile Creek, much of the older palaeosediments have recently been interpreted to be fluvial sediments of the Eyre Formation (Wopfner, et a!., 1974; Alley, 1998; Celerier, 2005) which are also considered to be the sedimentary host for the Four Mile Umineralisation in the area (Heathgate www.heathgateresources.com.au). Limited exposures of Mesozoic sediments have also been described along the range-front, particularly to the north of Four Mile Creek (Coats and Blissett, 1971; Callen, 1977; Callen, 1981; Sheard and Callen, 2000) and although these appear to be more restricted towards the south, an often overlooked interpretation on the Umberatana 1:63,360 (1 inch to 1 mile) Scale geology map (Geological Survey of South Australia, 1961) presents Mesozoic sediments along the range-front near Four Mile Creek. No previous characterisation or discussion of the interpretation of these sediments has been published. This study provides a detailed characterisation of these sediments exposed along the range-front in the upper Four Mile Creek drainage basin, and considers their palaeolandscape significance and the implications of this for mineral exploration. Proposed palaeodrainage directions from previous studies of the chosen area have been thought to follow a North-South trend (Dobrzinski, 1997). Previous interpretations have dated the palaeosediments as being from the Early Tertiary Eyre Formation. Tectonic movements in the Late Palaeocene to Middle Eocene led to the formation of the Lake Eyre Basin depocentre and uplift of the ancestral central South Australian highlands. Rapid subsidence within the basin promoted erosion of the weathered mantle around the basin margins.

Sedimentary uranium mineralisation was discovered at Beverley in the western part of the Frome Embayment in 1969. The deposit consists of three principal mineralised zones within a buried, confined palaeochannel containing unconsolidated sand and interbedded clay of the Tertiary Namba Formation. Mineralisation, which occurs at depths of 100-130 m, is separated from Cretaceous sediments of the Great Artesian Basin by at least 100 m of dense plastic clay (Alpha Mudstone). The principal ore mineral is coffinite, a uraniferous hydrosilicate thought to have been derived by leaching of primary mineralisation in the Mount Painter Inlier 12 km to the west. The total resource is 16 300 tonnes of U3O8 with the potential for more discoveries in the area. Regional geotechnical assessments identified potentially favourable fluviatile depositional environments adjacent to uranium enriched basement domains. The genetic model assumes leaching of uranium from permeable sands by oxidising ground waters, transport down the hydrological gradient, and deposition where reducing conditions prevailed at a classic redox interface. Heathgate Resources Pty Ltd acquired the deposit in 1990 and received Commonwealth and State environmental clearances in April 1999. Australia's first uranium mine using in situ leach (ISL) techniques was opened at Beverley on 21 February 2001. Production is currently around lOOOt/year of U3O8.

GEOLOGY AND MINERALISATION

WEATHERING HISTORY Regional deposition in the northern Flinders Ranges include both Mesozoic and Tertiary basin sediments. The Mesozoic comprises both marine and non-marine sediments. The non-marine sediments (eg Algebuckina Sandstone) are fluvial sandstones with an upper sequence of lower energy, fine grained, flood plain lacustrine and swamp sediments (Krieg et al., 1995). A transition from fluvial to marginal and shallow marine sediments is marked by quartzose and lithic sands and gravels named the Cadna-owie Formation. The marine sediments (eg Bulldog Shale) are mostly grey, fossiliferous mudstonesiltstone sequences with regressive marine sandstone (Krieg et al., 1995). These sediments display sedimentary structures such as cross bedding or fining upwards that are useful for palaeolandscape reconstruction.

SETTING The study area is along the range-front of the north-eastern Flinders Ranges, approximately 600 kilometres north of Adelaide, South Australia.

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Geological Society of Australia Abstract No. 87

VEGETATION The study area is a semi-arid rangeland subject to grazing. Dominant species include Emu Bush {Eremophela sp.), Dead Finish {Acacia tetragonophylla) and Spinifex {Triodia sp). Subdominating species include Mulga (Acacia sp.) and Bluebush (Maireana sp.) with Inland Tea-tree (Melaleuca glomerata) and conifers (Callitris sp.) established in major drainage channels.

11-

10-

COMPOSITE LOG

C^rcrettC %s' r/ ps^ bro^fn ScSJcsssi sedlr'^sr^s sWS in crack TTtom^^ ati ivier profite. iwy posf^y SrErte-d afrsylar •V-'V--" z aste«d arar-^ & tsnsuaft srsJSe smai ---Si cm J, (isntc ctasis "tra n V ! LPfe3^^(to*? m ovef Ss-te^te^iar, oGie sa-vdy MCS or meives tmcre. mate.l'aJ has iKe?^ 3v#s>. lL-r?py cfocSyi ^eaincmg EnSem

COMPOSITE LOG A composite log was created by linking elevations in an amphitheatre-like location of the study area and stacking the logged sections on one another to produce a complete section that can be interpreted as the Mesozoic stratigraphy of the area (Fig. 1). It is mainly coarse-grained silicious sediment the hosts some granitic, Kfeldspar lithics and gypsum and pyrite crystallisation.

m £r m m Q % m

ACKNOWLEDGEMENTS

OA-sh rec :4>B ' SVR> wtt? at'fitfci' grey verv pccrtyscfted sjtefsrte ncfiSiJtg; catearsas^ scr^s E-'nal IRf cs of CJii, mtea and pwflte msmUMi sfartg* anal psJe ' J ve?v coarse poowy bnvaw ri ^ .;S i •: a Crete s)a&>:S l oe:K Oa ' te i cirar^>« it coarse -.^ers' Eosfiy 5,2f5:«l tjc-anaijj' sard hssWrg sc^ne srr^g ism^ >3f Gj, x-i'eOspar mica and p>?tte, seme IKNcs Baic of itlhfcs 8g:Spa>5' msr^ciaial stmctuTe - i^tiSence cf apift, ri^lrsJy Qii oebictta S^TCSK) \n coarse •sf arargr icbs ^same as ^-iei^beiaw nk p:30:1y sofisec iarrd n^sdrg soT« srvalfcntazf Qu, K-fe<te?>sr nl-a a^d cyrfte O-aroe.'p nk coars- verj.- gMsary z-arisa santf graces Ir coteu?- dcwr: crsfHttocQa?se, Steaned. sTSOted liFfSer •Aitatsiered stiitars

I am very appreciative to CRC LEME and PIRSA's PACE funding for funding and supporting this project. This study greatly benefited from discussion and field work conducted with Steve More (PIRSA). Additional thanks to the other CRC LEME Students, Clint, Deanne, Jo, Miki and Rachael for support throughout the year. Finally I would like to thank Heathgate Resources Pty. Ltd. for allowing us to stay onsite at the Beverley Uranium Mine.

Sard of G.u p«£fr;«5 SypS4LfT DOl Cs-arwi, s>afe. tieacftedi ncmog«f>£Ois aaic TotlJed inE«r S i aBtne?ed su'fact jyptjm arjd Qu pMSb&:l a5.«rs rray tispiay isa te2d;-»B arrd rsTTOcsnal cip striicfejTie Ea''d cf arar^ssE murs i- O l cprs? 'i>aT« ncaceoiiE qaaTtz EesKea

References ALLEY N. F. 1998 Cainozoic stratigraphy, palaeoenvironments and geological evolution of the Lake Eyre Basin, Palaeogeography, Palaeoclimatology, Palaeoecology ^44, 239-263 CALLEN R. A. 1977 Late Cainozoic Environments of Part of North-Eastern South Australia, Journal of the Geological Society of South Australia, 24, 107-116 CALLEN R. A. 1981 Frome Map Sheet, South Australia, Explanatory Notes, 1:250,000 Series, Sheet SH 54-10 CELERIER J. 2005 Ceierier Field Sites, Journal of Virtual Explorer, 20 CHAMBERS L. E., 2003 South Australian rainfall variability and trends, Commonwealth Bureau of Meteorology, BMRC Research Report 92 COATS R. P. & BLISSETT A. H. 1971 Regional and economic geology of the Mount Painter Province, Geological Survey of South Australia, Bulletin 43. DOBRZINSKI I. 1997 Beverly and Honeymoon uranium projects, MESA Journals, 9-11 GEOLOGICAL SURVEY OF SOUTH AUSTRALIA 1961 Umberatana 1:63,360 (1 inch to 1 mile) Geological Map

Figure 1. Composite Sedimentary Log displaying what may be interpreted as Mesozoic sediments of the Four Mile Creek. Hector, A. N. (2007). HECTOR A. N. 2007 Upper Four Mile Creek Palaeosediments and associated palaeolandscape reconstructions, Eromanga Basin, Northern Flinders Ranges, South Australia, (Unpublished) KRIEG G. W., ALEXANDER, E. M. & ROGERS, P. A. 1995 In: Drexel, J. F. & Preiss, W. V. eds. The Geology of South Australia, Vol 2, The Phanerozoic , Bulletin Geological Survey of South Australia, 54, 101-123 SHEARD, M. J. & CALLEN, R. A. 2000 Callabonna Map Sheet South Australia Geological Survey, Geological Atlas 1:250,000 Series, Sheet SC 546 WOFNER, H., CALLEN, R. A. & HARRIS, W. K. 1974 The lower Tertiary Eyre Formation of the southwestern Great Artesian Basin, Journal of the Geological Society of Australia, 21, 17-52

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Geological Society of Australia Abstract No. 87

BIOGEOCHEMICAL TRACE ELEMENT CYCLING OVER THE FOUR MILE WEST URANIUM MINERALISATION BY INVERTEBRATE SOIL BIOTA M. R J e n n i n g s \ S. M. H i i r , C- W r i g h t ^ a n d J . K i r b / ^ CRC LEME, School of Earth & Environmental Sciences, University of Adelaide, SA, Australia 5005. ^ CSIRO Land and Water, Glen Osmond, Adelaide, SA Australia 5064.

biota. The activity of soil organisms such as earthworms, termites and ants may result in the development of a biomantle within the regolith. Chemical characterisation and investigation of this biomantle is therefore fundamental for constraining trace element dispersion and accumulation in soils, particularly for applications in mineral exploration and environmental geoscience. For mineral exploration applications, nest building soil biota such as ants and termites bring large quantities of buried material to the surface (deBruyn and Conacher 1990), which may contain chemical and physical expressions of subsurface mineralisation. Constraining the effects of soil biota on trace element movement has been one of the least developed components of geochemical mineral exploration. The majority of previous studies have focused on the physical translocation of regolith materials (Anderson 1988; Coleman and Crossley 2003; Lavelle et al. 2006) while a very few have attempted to quantify the movement of the trace elements contained within the materials. Most of these studies (Muller-Lemans and van Dorp 1996; Tyler et al. 2001; Zorn et al. 2005) have focused on the effect of earthworms on the transport of heavy metals or radionuclides. Earthworms are a dominant soil macrofauna in cool and wet climatic zones (deBruyn and Conacher 1990), but Australian macrofauna is mostly associated with arid and semi-arid settings with a prevalence of ants and termites. Termite mounds have been exploited for biogeochemical exploration programs (Tooms and Webb 1961; Gleeson and Poulin 1989; Leroux and Hambleton-Jones 1991; Petts and Hill 2005) but very little has been done to constrain the effects of ants. The few antrelated studies have focused on the transport and concentration of plant nutrients such as organic carbon, Ca, N, P and K (Wagner et al. 1997; Nkem et al. 2000; Wagner ef al. 2004). There has been very little quantification of the contributions of ants within the landscape. Biologically there has been extensive research of the Irldomyrmex purpureas species-group in

INTRODUCTION Biogeochemical mineral exploration using plants has had success in surficially expressing buried mineralisation (Dunn 1981; Brooks 1982; Kovalevsky 1987; Dunn 2007), as has the sampling of termitaria (looms and Webb 1961; Gleeson and Poulin 1989; Leroux and Hambleton-Jones 1991; Petts and Hill 2005). Other invertebrate soil biota and the regolith materials associated with their activity have not been widely assessed as exploration sampling media. Invertebrate biota, including ants and beetles, can accumulate trace elements such as uranium while living in contaminated ground (Rabitsch 1995b; Heikens 2001; Gongalsky 2006), but despite this, these media have not been tested for application to mineral exploration programs. Biogeochemical sampling methods have been under utilised as an exploration sampling media in Australia, even though biogeochemical exploration has been successful in both Canada and the former USSR (Dunn 1981; Kovalevsky 1987; Dunn 2007). Traditional' geochemical and geophysical exploration methods have been preferentially used with great success in Australia, however their effectiveness may be limited in areas of deeply buried mineralisation. Biogeochemical media can complement existing methods by increasing the chances of detecting subtle and complex transported geochemical expressions of buried mineralisation. It is relatively cost effective, compared to methods such as drilling, may be adapted easily to suit most landscape settings, and is of minor environmental impact (especially compared to drilling rigs), allowing it to be used effectively in culturally or environmentally sensitive sites. Soil biota forms an intrinsic part of the regolith, exerting a fundamental influence on the physical and chemical properties of soils (Anderson 1988; Lai 1988; Cammeraat et al. 2002; Wagner et al. 2004; Jouquet et al. 2006). The rates of soil turnover, soil profile development, water infiltration and nutrient concentration can be greatly influenced by soil

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Geological Society of Australia Abstract No. 87

in order to characterise the ant-related biogeochemical expression of the buried Umineralisation, as well as U-rich bedrock within the catchment headwaters. The mineralisation was best expressed by a suite of eleven elements (Au, Be, Cu, Gd, La, Se, Sm, Th, U, V and Y) (Jennings 2007). The ants express a geochemical dispersion halo associated with the buried bedrock and mineralisation (Fig. 1) whereas the nest soils were mostly derived from surficial, transported and re-worked materials (Fig. 2). The ant assays ranged from 0.027 to 13 ppm U, while the nest soils ranged from 3.5 to 118 ppm U, and although absolute assay values for U may have been higher in the soils, the ants provided a greater background to anomaly contrast. The ants were also compared with vegetation sampled as part of a previous study conducted in the area by Neimanis and Hill (2006); in order to further compare their value as a potential exploration sampling medium. The ants expressed the underlying mineralisation in a similar manner to that of the plants, suggesting that both of these media have potential to provide surficial chemical expressions that have penetrated surficial transported regolith. This study highlights the prospective use of soil biota as a biogeochemical sampling medium, particularly since ants are ubiquitous in arid Australian landscapes.

Australia, but the majority of work has focused on taxonomy and distribution (Greaves 1971; Greenslade 1974; Shattuck 1993). Iridomyrmex spp. form one of the largest and most ubiquitous ant groups in Australia, and are also found in India, China and New Caledonia (Shattuck 2001). The meat ants (Iridomyrmex purpureas group) are large, aggressive and often construct prominent nest mounds. These are large (2 m wide), bare patches of gravel-covered ground. Meat ants are large and aggressive, and thus more readily sampled than smaller or cryptic species. Colonies are large and typically consist of nests linked together by foraging trails that may extend laterally for hundreds of metres (van Wilgenburg et al. 2006). Nests are permanent structures that may remain active for decades (Greenslade 1974a). Iridomyrmex spp. are widespread and abundant throughout Australia, making them a potentially valuable sampling media. Although ants are an integrally associated with the regolith and landscapes of much of the world, there have been very few studies that have accounted for the chemical characteristics of this association. This biogeochemical study focuses on the contribution of ants to the landscape geochemistry of a low order headwater catchment of the Four Mile Creek drainage basin. Ants and ant nest soils were sampled and subjected to multi-element assays

356500

356500 0

•

455 •

Legend

Metres 910 I

1,820

^ ^

Projected Mineralisation

Uranium (ants) Value (ppm) O

GRID NORTH GDA1994 (Zone 54)

0.027-1.417 1.418-4.302 4 . 3 0 3 - 13.035

Figure 1. Biogeochemical map representing the distribution of uranium assays in ants.

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Geological Society of Australia Abstract No. 87

358500

355500 ^^

356500

Legend ^ ^

Projected Mineralisation

Uranium (nest material) Value (ppm) O

GRID NORTH GDA1994 (Zone 54)

3.5 - 30.0

30.1 - 57.0

^ ^

57.1 - 1 1 8 . 0

Figure 2. Geochemical map representing the distribution of uranium assays in ant nest soils.

References ANDERSON J.M. 1988. Invertebrate-mediated transport processes In soils. Agriculture, Ecosystems & Environment 24(1-3): 5-19. BROOKS R.R. 1982. Biological Methods of Prospecting for Gold. Journal of Geochemical Exploration 17(2): 109-122. CAMMERAAT L.H., WILLOTT S.J., COMPTON S.G. & INCOLL L.D. 2002. The effects of ants' nests on the physical, chemical and hydrological properties of a rangeland soil in semi-arid Spain. Geoderma 105(1-2): 1-20. COLEMAN D.C. & CROSSLEY D.A.J. 2003. Fundamentals of Soil Biology, Elsevier Science. DEBRUYN L.A.L. & CONACHER A.J. 1990. The Role of Termites and Ants in Soil Modification - a Review. Australian Journal of Soil Research 28(1): 55-93. DUNN C.E. 1981. The Biogeochemical Expression of Deeply Buried Uranium Mineralization in Saskatchewan, Canada. Journal of Geochemical Exploration 15(1-3): 437-452. DUNN C.E. 2007. Handbook of Exploration and Environmental Geochemistry Volume 9: Biogeochemistry in Mineral Exploration. Amsterdam, Elsevier. GLEESON C.F. & POULIN R. 1989. Gold Exploration in Niger Using Soils and Termitaria. Journal of Geochemical Exploration 31(3): 253-283. GONGALSKY K.B. 2006. Bioaccumulation of metals by soil-dwelling insects in a uranium production area. European Journal of Soil Biology 42: 180185.

GREAVES T. 1971. The Distribution of the Three Forms of the Meat Ant Iridomyrmex purpureus (Hymenoptera: Formicidae) in Australia. Australian Journal of Entomology 10(1): 15-21. GREENSLADE P. 1974a. Distribution of Two Forms of the Meat Ant, Iridomyrmex Purpureus (Hymenoptera: Formicidae), in Parts of South Australia. Australian Journal of Zoology 22(4): 489-504. GREENSLADE P.J.M. 1974b. Some relations of the meat ant, Iridomyrmex purpureus (hymenoptera: formicidae) with soil in South Australia. Soil Biology and Biochemistry 6(1): 7-14. HEIKENS A., PEIJNENBURG W.J.G.M., & HENDRIKS A.J. 2001. Bioaccumulation of heavy metals in terrestrial invertebrates. Environmental Pollution 113(3): 385-393. JENNINGS M.F. 2007. Soil biota contributions to surficial geochemical signatures through transported regolith. Four Mile Catchment near Beverley Uranium Mine, SA. BSc (Hons) thesis. University of Adelaide (unpubl.) JOUQUET P., DAUBER J., LAGERLOF J., LAVELLE P. & LEPAGE M. 2006. Soil invertebrates as ecosystem engineers: Intended and accidental effects on soil and feedback loops. Applied Soil Ecology 32(2): 153-164. KOVALEVSKY 1987. Biogeochemical Exploration for Mineral Deposits. Utrecht, The Netherlands, VNU Science Press.

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SHATTUCK 8 . 0 . 1999. Australian ants: their biology and identification., CSIRO Publishing. T 0 0 M 8 J.S. & WEBB J.S. 1961. Geochemical prospecting investigations in the Northern Rhodesian copperbelt. Economic Geology 56(5): 815-846. TYLER A.N., CARTER S., DAVIDSON D.A., LONG D.J. & TIPPING R. 2001. The extent and significance of bioturbation on Cs-137 distributions in upland soils. Catena 43(2): 81-99. VAN WILGENBURG E., MULDER R.A. & ELGAR M.A. 2006. Intracolony relatedness and polydomy in the Australian meat ant, Iridomyrmex purpureus. Australian Journal of Zoology 54(2): 117-122. WAGNER D., BROWN M.J.F. & GORDON D.M. 1997. Harvester ant nests, soil biota and soil chemistry. Oecologia 112(2): 232-236. WAGNER D., JONES J.B. & GORDON D.M. 2004. Development of harvester ant colonies alters soil chemistry. Soil Biology & Biochemistry 36(5): 797-804. ZORN M.I., VAN GESTEL C.A.M. & EIJ8ACKER8 H. 2005. The effect of two endogeic earthworm species on zinc distribution and availability in artificial soil columns. Soil Biology and Biochemistry Z7{5y. 917-925.

LAL R. 1988. Effects of Macrofauna on Soil Properties in Tropical Ecosystems. Agriculture Ecosystems & Environment 24(^-3y. 101-116. LAVELLE P., DECAENS T., AUBERT M.. BAROT S., BLOUIN M.. BUREAU F.. MARGERIE P., MORA P. & ROSSI J.P. 2006. Soil invertebrates and ecosystem services. European Journal of Soil Biology 42: 83-815. LEROUX J.P. & HAMBLET0N-J0NE8 B.B. 1991. The Analysis of Termite Hills to Locate Uranium Mineralization in the Karoo Basin of South-Africa. Journal of Geochemical Exploration 41(3): 341347. MULLER-LEMANS H. & VAN DORP F. 1996. Bioturbation as a mechanism for radionuclide transport in soil: Relevance of earthworms. Journal of Environmental Radioactivity 31(1): 720. NEIMANIS M.J. & HILL S.M. 2006. Plant Biogeochemical Expression on Uranium Mineralisation in Australia: Research Outline and Preliminary Results. In: R. W. Fitzpatrick and P. 8hand (Eds) Regolith 2006: Consolidation and Dispersion of Ideas., CRC LEME. NKEM J.N., DE BRUYN L.A.L., GRANT C.D. & HULUGALLE N.R. 2000. The impact of ant bioturbation and foraging activities on surrounding soil properties. Pedobiologia 44(5): 609-621. PETTS A.E. & HILL S.M. 2005. Regolith-Landforms and Mapping of the Coyote Au Deposit, Tanami Desert, Northern Territory. Regolith 2005 - Ten Years of CRC LEME, CRC LEME. RABITSCH W.B. 1995. Metal accumulation in arthropods near a lead/zinc smelter in Arnoldstein, Austria. II. Formicidae. Environmental Pollution 90(2): 239-247. 8HATTUCK 8. 1993. Revision of the Iridomyrmex purpureus species-group (Hymenoptera Formicidae). Invertebrate Systematics 7(1): 113149.

ACKNOWLEDGEMENTS Many thanks are due to Jess Oram and Heathgate Resources for their fantastic logistical support; CRC LEME for their financial assistance; PIRSA for PACE funding and for lending us the wonderful Steve More and his encyclopaedic knowledge of the northern Flinders Ranges geology. Thanks also to Archie McArthur (SA Museum), for ant ID, and to Claire Wright and CSIRO for taking on the ant analysis.

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ELECTROMAGNETICS FOR MINERAL EXPLORATION AND ENVIRONMENTAL STUDIES - RESULTS FROM SOUTH AUSTRALIA AND NORTHERN TERRITORY J o h n Joseph^'^, A d r i a n Fabris^'^ a n d L i s a Worrall^'^ ^ Cooperative Research Centre for Landscape, Environment and Mineral Exploration ^School of Earth & Environmental Sciences, University of Adelaide, Adelaide, Australia 5005 ^ PIRSA, PO Box 1671, Adelaide, Australia 5001 Geoscience Australia, GPO Box 378, Canberra, Australia 2601

This paper shall focus mainly on the transient electromagnetic (TEM) technique. This method can be used for vertical depth sounding or profiling. The equipment consists of a transmitter and receiver, which can be contained in a single box (with an external power source for the transmitter) or used with separate transmitter and receiver enclosures (Zonge and Wynn, 1975). The depth of exploration attained in a vertical sounding configuration can vary from 10's of meters to over 1000 meters, depending on transmitter loop size, available power from the transmitter, conductivity distribution of the subsurface and ambient noise levels. Figure 1 shows a cartoon of the TEM survey set-up used.

Among the geophysical methods, electromagnetics (EM) have the broadest range of instrumental systems and remarkably wide range of applications. The main physical property involved in this technique is electrical conductivity (o), which is a measure of how easily electric current can pass through a material. Some times this property is represented as its reciprocal (l/o), which is known as electrical resistivity (p). Conductivity within the subsurface is a complex function of several variables, which includes the conductivity of the material or rocks depending on their chemical or mineralogical composition, its porosity, conductivity of pore fluids and degree of saturation (e.g. Grant and West, 1965; Reynolds, 2000). The "active" nature of EM systems is in strong contrast to passive magnetic, gravity or gamma-ray spectrometric methods (Nabighian, 1987). Hardware limitations on signal-to-noise and bandwidth lead to proprietary configurations and added complexity in the processing and interpretation of EM data. The electromagnetic techniques can generally be classified as (1) transient or time domain (TEM) where the measurements are made as a function of time, and (2) frequency domain (FEM) systems which use one or more frequencies. EM Systems measure the conductivity of the ground by inducing an electrical field through the use of time-varying electrical currents in transmitter coils located above the surface of the ground (Telford et al. 1990). These time-varying currents create magnetic fields that propagate in the earth and cause secondary electrical currents, which can be measured either while the primary field is transmitting (FDEM) or after the primary field has been switched off (TDEM). The main advantage of the EM methods is that they do not require direct contact with the ground as in the case of DC resistivity methods. Therefore the EM measurements can be carried out in a faster way than the DC measurements.

Transmitter loop (100 xioom)

Receiver Transmitter Figure 1. A cartoon showing the TEM system set-up. A transmitter and a receiver with power supply, a square shaped transmitter loop and receiver coil at the centre of the loop that is supported by a tripod.

The TEM source consists of a fast turn-off, high current transmitter driving a large loop placed on the ground. The actual size of the loop depends upon the depth of investigation desired and the amount of area to be covered. A batterypowered transmitter will produce currents of up to 6 amperes in a typical loop, and high-powered generator driven transmitters can produce 50

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Geological Society of Australia Abstract No. 87

amperes or more. The current is cycled on and off in pulses of alternating polarity. Receiver measurements are made during the off time when only the secondary fields are present. A pulse of energy is put into the ground during the current turnoff time, and the voltage generated in the receiver loop or magnetic coil antenna is measured as the induced energy diffuses into the earth. Since the depth of penetration is a function of delay time, the measurements made at a number of delay times can be used to determine the variation in conductivity with depth. The process of determining conductivity is related to taking the difference between measurements at successive delay times. Shallow vertical resolution is determined by early time performance. The depth of penetration is determined by performance at late time. The Intermediate times provide the detail between these two extremes. Figure 2 shows an example of magnetic decay response (db/dt) from one of the field sites and the 1-D depth-resistivity profile obtained after applying smooth inversion technique (Maclnness and Raymond, 2001). Interpretation of TEM data can be considered as a four-step process. First, the data are assessed in terms of quality. Next, the data are related to subsurface conductivity. Then the conductivity distribution is related to units of more direct significance to the application (e.g. pore fluid salt concentration in soil salinity applications or discrete massive sulphide bodies in base metal exploration applications). Finally, the mapped EM response is fully integrated with all other information (geophysical, geochemical and hydrological information) in the survey area for final interpretation. Regolith land-forms with common provenance and subjected to similar weathering processes can produce spatially coherent EM responses. But in general, regolith materials do not posses unique conductivity values. This can be due to the influence of pore fluid conductivity and the extent of saturation making it difficult to construct a reference chart of conductivity values for different regolith-landform units. This situation resulted in base-metal explorers considering regolith materials as major sources of noise. It has later been realised, that mapping of conductivity variation within regolith landforms can have an application as an adjunct for detecting discrete conductors. Similarly, EM techniques have application in mapping the groundwater of remote areas and monitoring salinity issues and related environmental problems of urban and farmlands. This paper discusses results of TEM surveys conducted for imaging the shallow subsurface conductivity

Model Resistivity (ohm

Figure 2. An example of TEM response (db/dt) observed at one of the stations at Kalakaroo mineral prospect (top). 1-D Depth-resistivity calculated from the TEM response using smooth inversion technique (bottom).

distribution at the Kalkaroo Cu-Au-Mo Deposit in South Australia and the Titania Prospect in the Tanami desert. Northern Territory. Survey results are compared with other geological /geophysical

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information. These studies were conducted as a part of on-going CRC-LEME sponsored multidisciplinary projects with an objective of enhancing the ability for exploration in areas of regolith cover. References GRANT F. S. & WEST G. F. 1965. Interpretation theory in Applied Geophysics. New York: McGraw-Hill. MACINNESS S & RAYMOND M. 2001. STEMINV Documentation - Smooth-Model TEM inversion,

v3.0, Zonge Engineering and Research Organisation Inc. NABIGHIAN M. N. 1987. Electromagnetic Methods in Applied Geophysics, Vol. 1, Society of Exploration Gephysicists Tulsa. REYNOLDS J. M. 2000. An introduction to applied and environmental geophysics John Wiley & Sons Publications, New York. TELFORD W. M. GELDART L. P., SHERIFF R. E. & KEYS D. A. 1990. Applied Geophysics, 2"^ Edn. Cambridge: Cambridge University Press. ZONGE K.L. & WYNN J.C. 1975. Recent advances and applications in complex resistivity measurements. Geophysics 40(5), 851-864.

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Dr R C SPRIGG - CONTRIBUTIONS TO GEOLOGY AND INSIGHTS INTO LANDSCAPE EVOULTION J.L, Keeling^ and S.B. Hore^ ^ CRC LEME / Geological Survey, PIRSA, GPO Box 1671, Adelaide, Australia, 5001 ^ Geological Survey, PIRSA, GPO Box 1671, Adelaide, Australia, 5001

to Santos Ltd, Sprigg secured tenure to vast tracts of country in northwest South Australia and southwest Queensland. In 1957, he accompanied Santos Director John Bonython to the United States to promote the petroleum potential of the western Great Artesian Basin, a trip that led to the alliance with Delhi and subsequent discovery of gas in the Cooper Basin. Sprigg was a founder of petroleum explorer, Beach Petroleum NL, in 1962. In 1968 he purchased the Arkaroola Pastoral Lease and established a wildlife sanctuary, wilderness reserve and tourist resort. In that year he was also the recipient of the Verco Medal from the Royal Society of South Australia. He was appointed an Officer of the Order of Australia (AO) in 1983.

BACKGROUND Reginald Claude Sprigg was born on 1 March 1919 in Stansbury on Yorke Peninsula, South Australia. His interest in fossils was fostered at an early age by ready access to fossil remains of Tertiary marine life weathered from limestone cliffs near his Stansbury home. Mineral collecting followed a chance meeting at age 10 with an exBroken Hill miner in Adelaide who provided the boy with mineral specimens from Broken Hill, Burra and Glen Osmond Mines (Sprigg, 1989). Sprigg was encouraged in his fossil collecting by Professor Walter Howchin, then in his eighties, and the youth's enthusiasm for geology was recognised by election to membership of the Royal Society of South Australia at the age of 17 years. He completed a Master of Science degree in Geology at Adelaide University in 1941. Here his geological studies and knowledge were greatly influenced by close contact with outstanding geologists and explorers Professor Sir Douglas Mawson and Dr Cecil Madigan. In 1941, Sprigg was posted to Munitions with the Australian Royal Engineers and was later moved to work as a research officer with the Soils Division of CSIR based at Waite Institute in Adelaide. He worked for a time in Tasmania mapping soils suitable for growing carrots and later assisted in the assessment of sites in South Australia with potential for Post-War Soldier Settlement. In 1944, he transferred to the Geological Survey of the South Australian Department of Mines. Between 1944 and 1954, Sprigg was involved with geological mapping of the Radium Hill Uranium Mine prior to reopening the mine in 1954; mapping uranium occurrences at Arkaroola in the northern Flinders Ranges; regional geological mapping, particularly in the South East, but also in the Flinders Ranges, Olary district and the state's northwest. This work incorporated early airborne radiometric surveys and the introduction of aerial photography to aid regional geological mapping. He resigned from the Mines Department in 1954 and established consulting group Geosurveys of Australia Pty Ltd. As a consultant

Figure 1. Dr R C Sprigg AO MSc DSc (1919-1994)

GEOLOGICAL CONTRIBUTIONS Reg Sprigg's geological interests were broad and this was coupled with enthusiasm and energy for his chosen profession. His career included aspects of academic research, government and industry. As such his contributions to the geological sciences have been numerous.

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although incompletely recorded. Those for which he is widely recognised include the discovery in 1946 of the sonne of the world's earliest animal fossils at Ediacara; the discovery in 1947 of submarine canyons along the edge of the continental shelf south of Kangaroo Island; recognition that 'youthful' domed sediments in the south-western Great Artesian Basin were a reflection of possible large-scale anticlinal traps for petroleum (Sprigg, 1958).

Fossils similar to those from Ediacara have now been identified from all continents, except Antarctica. Their significance was recognised in 2004 by the establishment of a new time period in the geologic time scale - Ediacaran [--635 543 Ma]. This is the first stratigraphically defined new period to be added in 113 years (Knoll et al., 2004).

LANDSCAPE EVOLUTION Regolith was not a term in general geological usage during Sprigg's career. Yet his broad interests in anything geological meant that he made several significant contributions on landscape and landscape history. Some examples from early in his professional life include:

Ediacara Faunas in 1946, Sprigg found a single circular fossil in flaggy sandstone while doing detailed geological mapping along the southern end of the old Ediacara lead-zinc-copper mineral field. Aware that this was from rocks older than any previously recorded animal fossil, he exhibited his find at the ANZAAS Conference in Adelaide later that year. The specimen attracted little interest and no consensus that the find was indeed a fossil. The following year he had the opportunity to revisit the site in the company of Premier Playford during an inspection of Mines Department diamond drilling for lead-zinc mineralisation. Sprigg used the opportunity to 'fossil hunt' and this time found an abundance of fossil forms in sandstone slabs "scattered profusely down a small slope" (Sprigg, 1989). Although the Premier was unimpressed by the academic diversion. Professor Mawson, when later shown the variety of fossil forms, agreed that this was indeed a very significant find. Sprigg carefully described and photographed the specimens and published the results through the Royal Society of SA (Sprigg, 1947). A note to international journal "Nature" was not accepted. The international scientific indifference to his discovery was frustrating for Sprigg. It was left to Professor Martin Glaessner, who joined the faculty at Adelaide University in 1950, together with Mary Wade to bring the find to international attention in the early 1960s. The 1940s and 50s remained a time of scepticism within the scientific community of any evidence of life prior to the Cambrian period. The Ediacaran biota pushed back the fossil record a further 30 million years into the Precambrian. Their forms provided explanation for lack of preservation of soft-bodied animals and helped to raise the curtain on the mystery of the missing record of Precambrian life. The revelation increased acceptance of evidence of petrified cellular microbes that today show life has been present on Earth for nearly 3,500 million years, more than three quarters the age of the Earth, not the mere 543 million years which marks the beginning of the Cambrian.

Adelaide Soils and Geology Sprigg's time with CSIR, later CSIRO, Division of Soils was short but he was quick to pick up on new scientific ideas of the time from Bob Crocker (Post-Miocene climatic and geological history of Australia) and Professor Prescott (rock weathering and soil development). Following transfer to the Department of Mines, Sprigg maintained his professional association with Soils Division and was a joint author with Gordon Aitchison and Greg Cochrane on The Soils and Geology of Adelaide and Suburbs (Aitchison etal., 1954). The publication combined detailed description of type soil profiles, together with excellent colour plates for the time, soil distribution maps and engineering properties of the various soil types, including comment on characteristics affecting domestic foundations. All this was placed in a geological context that included past geological history and climatic influences on soil development and their inherent properties. Sprigg was well placed to contribute expertise to the publication having in his own time completed detailed geological mapping of the western Mount Lofty Ranges near Adelaide (Fig. 2) (Sprigg, 1942; Sprigg, 1946). This work was incorporated in the newly published '1-mile to an inch' (1:63,360 scale) geological maps of Adelaide and Echunga (Sprigg et al., 1951; Sprigg and Wilson, 1954). In the domestic building boom of post war Adelaide the soil publication provided essential scientific knowledge to underpin innovative engineering design for domestic footings to cope with various problematic swell-shrink clay soils of the Adelaide Plains. Backed by testing facilities of the Soil Physics and Mechanics group at CSIRO, this publication and later detailed soil maps served the public and geotechnical consultants for some 40 years before the work was updated

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Sprigg was attracted to an explanation provided by the Milankovitch solar climatic theory of the 1930s. Milankovitch argued that perturbations in the Earth's orbit led to fluctuations in the quantity of solar radiation received at particular latitudes. These "perturbations" have periods of 10s of thousands of years and Sprigg produced a correlation between predicted summer radiation maxima and the pattern of stranded South East dunes (Sprigg, 1952). He later modified these correlations arguing that the calcarenite dunes of the South East were a record of sea level low stands and from this arrived at an estimated age for the Naracoorte Dune at 690-700 thousand years (Sprigg, 1989). This compares to 780 thousand years subsequently reported for the period between formation of East and West Naracoorte dunes, based on reversal of magnetic polarity in precipitated iron oxides, equated to the Brunhes/Matuyama polarity transition.

in 1994 (Sheard and Bowman, 1996), in another Mines Department/CSIRO Soils collaboration. When Sprigg resigned from the Mines Department in 1954, he added to his consulting ventures, Soilab Pty Ltd and Geotechnical Laboratories in partnership with trained soil engineers (Sprigg, 1989). However difficulties in directly influencing practices in the contract building industry and the potential for litigation were incentives enough for him to withdraw from this line of consulting. The work was left to soil engineering firms with the financial resources to take out expensive legal indemnities.

South East Coastal Dunes in 1947, Sprigg was requested to carry out investigations at Robe Harbour in connection with the possibility of developing a safe, major seaport and harbour to service the South-East coast (Sprigg, 1989). The breached aeolian, calcreted dune with numerous shallow reefs proved unsuitable for harbour development, as did other potential sites along this exposed and inhospitable coast. The investigation did provide Sprigg the opportunity to study the magnificently preserved series of stranded coastal beach ridges. These are hundreds of kilometres in length, and extend inland for a 100 kilometres as 15 to 20 parallel, stranded and separate fossil coasts. Initial investigations were followed up in 1949 and 1950 leading to publication of a series of Geological Survey standard maps and a bulletin on "Geology of the South-East Province, South Australia, with Special Reference to Quaternary Coast-line Migrations and Modern Beach Developments" (Sprigg, 1952). The beach dunes are a record of sea level changes over the past 1 million years driven by climatic fluctuations in the dominantly Pleistocene Ice Age. Sprigg was able to demonstrate that that the dunes have been modified by regional downwarping to the northwest away from relative uplift in the Mt Gambier-Mt Burr volcanic region. Later he showed that at least another four beach dunes were present, the farthest some 20 km offshore and indicating sea level oscillations of the order of 100 m. With Geosurvey's oceanographic survey ship MV SAORI, Sprigg confirmed the presence of kilometre-deep submarine canyons etched into the continental slope south of Kangaroo Island. He argued that these were eroded by bottom oceanic flow of muddy water discharged from an ancestral River Murray, and other forgotten rivers draining out of the Gulfs, during times of low sea level in the Pleistocene (Sprigg, 1993). While acknowledging that the factors driving glacial and interglacial periods during an ice age that result in sea level fluctuations are complex,

Reg Sprigg showed that he was a keen observer in the field, with a strong drive to understand the wider implications of what he uncovered. Coupled with his energy, broad knowledge of geology and a willingness to test his theories, it should come as no surprise that his name is coupled with significant breakthroughs in geology. This symposium is an opportunity to reflect on his achievements and to take inspiration from his contribution as we tackle the exciting geological challenges ahead. References AITCHISON G.D., SPRIGG R.C. & COCHRANE G.W. 1954. The soils and geology of Adelaide and suburbs. Geological Survey, South Australia, Bulletin 32, 126pp. KNOLL A H . , WALTER R.M., NARBONNE G.M. & CHRISTIE-BLICK N. 2004. A new period for the geologic time scale. Science 305, 621-622. SHEARD M.J. & BOWMAN G.M. 1996. Soils stratigraphy and engineering geology of near surface materials of the Adelaide Plains. Primary Industries and Resources, South Australia. Report Book, 1994/09. SPRIGG R.C. 1942. The geology of the Eden-Moana fault block. Transactions Royal Society of South Australia 66, 185-214. SPRIGG R.C. 1946. Reconnaissance geological survey of portion of the western escarpment of the Mount Lofty Ranges. Transactions Royal Society of South Australia 70, 313-347. SPRIGG R.C. 1947. Early Cambrian(?) jellyfishes from the Flinders Ranges. Transactions Royal Society South Australia 71, 212-214. SPRIGG R.C., WHITTLE A.W.G. & CAMPANA B. 1951. Adelaide map sheet. South Australia, Geological Survey, Geological Atlas 1:63 360 Series.

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SPRIGG R.C. 1952. The Geology of the South-East Province, South Australia, with special reference to Quaternary coast-line migrations and modern beach developments. Geological Survey, South Australia, Bulletin 29, 120pp. SPRIGG R.C. & WILSON B. 1954. Echunga map sheet. South Australia, Geological Survey, Geological Atlas 1:63 360 Series.

SPRIGG R.C. 1958. Petroleum prospects of western parts of the Great Artesian Basin. American Association of Petroleum Geologists Bulletin 42(10), 2465-2491. SPRIGG R.C. 1989. Geology is Fun. Gillingham Printers Pty Ltd, Adelaide. SPRIGG R.C. 1993. A Geologist Strikes Out. Gillingham Printers Pty Ltd, Adelaide.

Figure 2. Geological map of portion of the western Mt Lofty Ranges south of Adelaide (from Transactions of the Royal Society of South Australia, (Sprigg 1942)).

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GOLD IN CALCRETE - TWENTY YEARS ON MJ. Lintern CRC LEME/CSIRO Exploration and Mining, PO Box 1130 Bentley WA6102. mel.lintern@csiro.au

EARLY EXPERIMENTS AND OBSERVATIONS - W. AUSTRALIA

INTRODUCTION The Au in calcrete association was discovered twenty years ago in Western Australia (Lintern, 1989; Fig. 1). Case studies at numerous Au deposits and prospects followed this breakthrough, and showed it to be widespread. A practical exploration technique was developed to explore semi-arid, deeply weathered landscapes throughout southern Australia (Lintern and Butt, 1997). The method was further refined for the Gawler Craton by Kevin Wills (then Dominion Mining Ltd) where calcrete was sampled on a 1.6 km grid.

The soluble nature of Au was shown with extraction experiments using calcrete and deionised water (Fig. 2). For a range of samples, -20% (but occasionally up to 80%) of Au in carbonate is soluble in deionised water. Some of this Au may be re-adsorbed onto soil particles (Gray and Lintern, 1993).

Au ppb 0

200 400 600 800 1000 1 80-

—A- - Rne (grass) - - Coarse

T}mB(days) Figure 2. Solubility of Au in calcrete sample from Bounty using deionised water (see Gray and Lintern, 1998).

The effect of micro-organisms on the solubility of carbonate Au was studied by comparing the behaviour of irradiated with natural samples of carbonate-rich and of organic-rich soil (Grayet al., 1990). Carbonate soils were found (1) to have lesser involvement of micro-organisms in the preprecipitation of dissolved Au and (2) to be less repressive at Au dissolution than organic-rich soils. Recently, Reith and Schmidt Mumm, (2007) have expanded this research and investigated the possibility of microbial populations involvement in the co-precipitation of Au and Ca to form calcrete anomalies. An important early observation of significance to mineral explorers was that Au in calcrete may "see through" shallow thicknesses of transported overburden (e.g. Bristow et al., 1996, Fig. 3).

Figure 1. The discovery of Au in calcrete at Bounty.

Much was made of the discovery of the Challenger Gold Deposit in South Australia in 1995 (now >1 M oz), but earlier than this many WA mines had had their lives extended due to calcrete sampling (Edgecombe, 1997). Calcrete sampling has been used elsewhere, particularly in central Asia, southern Africa and the Americas. In Australia, calcrete sampling for Au continues to be used extensively and successfully, particularly in the Gawler and Yilgarn Cratons e.g. Tropicana. An internet search of "calcrete Au" produces about 19000 hits, many linking to company reports. Increasingly, calcrete is being used to explore for other commodities such as base metal and U deposits.

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Ca (%) 10 L i z Sandy silt (indurated by Fe oxides and silica towards base) with a few fragments of weal^ly to moderately weathered, non ferruginous, angular, polymictic gravels overlain by 0.5-1.0 m of dominantly sheetwashed and minor aeolean sands. Au (ppb) #>180 • 60-180 • 20-60 7-20 • <7

395 r

- 395

390

Depth (mASL)

385"--*

385

-380

380

450400

450600

450800

451000

451200

451400 mE

Figure 3. Gold expression in calcreted transported overburden above mineralization at Safari

Luminescence dating showed that the soil profiles containing calcrete can be more than 200 000 old (Sheard et al., 2006); older calcretes would be expected to contain more Au than younger ones. Isotope studies showed that the Ca in calcrete has its origins in atmospheric additions of marine origin (Lintern, 2004; Dart et ai, 2005; Lintern et al., 2006); thus, mineral explorers need not be concerned about whether rock weathering sources Ca or not, since calcrete can form irrespective of lithology.

Vegetation also contains Au and is implicated in the process of calcrete anomaly formation. Thus, plant roots suck up Au into leaves and tissues from beneath the transported overburden only for this to be returned to the regolith in litter and soil. From the soil the Au percolates down where it accumulates with the calcrete over time. However, one issue with this model is the absence of proof that the Au in calcrete and soil was derived from depth since some (or all) may have moved laterally into the soil and calcrete from upslope (rather than vertically) as part of colluvial processes. Recently, however, research at Barns confirmed the role that vegetation is indeed moving Au to the surface from beneath (see below).

Recent Experiments and Observations from Barns Prospect Recently, the Barns gold prospect in the Eyre Peninsula, South Australia has become an important site for on-going Au-calcrete research involving biological, microbiological, luminescence dating, and isotope geochemical applications (McEntegart and Schmidt Mumm, 2005; Lintern, 2007; Schmidt Mumm and Reith, 2007). The prospect is located in highly weathered Proterozoic rocks, overlain by at least 1 m of aeolian quartz sand that thickens to 8 m as a longitudinal sand dune over part of the mineralization (Fig. 4). The dune is wellvegetated, with Melaleuca shrubs, and Eucalyptus trees up to 5 m high. Over mineralization, there are anomalous Au concentrations in plant organs, litter, soils and sand. The highest Au concentrations (9 ppb) occur in calcareous rhizomorphs high up within

OBSERVATIONS FROM SOUTH AUSTRALIA In South Australia, regolith investigations at several Au prospects highlighted the importance of geomorphology and paleolandscapes for anomaly formation. Calcrete is ubiquitous in the southern Gawler and parts of the Curnamona Cratons, and commonly dominates the soil profile to several metres depth (Lintern and Sheard, 1998; Skwarnecki et al., 2001). A regolith study at Old Well (Gawler Craton) showed how a Au in calcrete anomaly follows a paleodrainage channel for several kilometres (Gibbons and Lintern, 1998) indicating how Au and Ca have moved around in ancient landscapes.

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Figure 6. Gold phytonuggets (arrowed) in Acacia stem grown in vivo

Figure 4. Rounded quartz supported by micritic carbonate from Barns dune. FOV -300 pm wide

CONCLUSION

the dune suggesting Au calcrete anonnalies can fornn during the life of a tree. Thus a biological process, principally involving vegetation, is the most likely mechanism for the Au accumulation in the calcareous sand at Barns (Fig. 5). Based on experiments using samples from Barns, it has been suggested that bacteria may control the precipitation of carbonate and Au due to a pH change through the decomposition of organic molecules such as urea (Schmidt Mumm and Reith, 2007). However, one problem with this mechanism is that bacteria are mostly concentrated at the top of the soil profile (where the organic material is located on which they feed) while the Ca and Au precipitation occurs deeper in the profile where bacterial populations are only a fraction of what they are at the surface. This is not to say that bacteria do not have a role to play in the Au-calcrete formation process. For example, many common soil micro-organisms produce cyanide and Au forms a strong complex with this anion; a strongly complexed AuCN molecule will be mobile within the soil profile.

Since the early years of discovery there have been few technical breakthroughs in our knowledge of the "how, why and where" of this important Au association. In recent years, however, with the advent of CRC LEME, increasing emphasis has been placed on geochemical process understanding and, as a result, we are now better informed of how calcrete anomalies may form; as to whether this new knowledge will translate to improving the rate of discoveries remains to be seen. In the mean time, calcrete sampling, as with any other successful surficial sampling technique, will continue to be used to find mineral deposits around the world. Acknowledgements I would particular like to acknowledge C.R.M. Butt, D.J. Gray, R.R Anand, M,J. Sheard, G. Gouthas and many others that have contributed to the advancement of our understanding of Au in calcrete. ORG LEME, who partly funded the work, is supported by the Australian Cooperative Research Centres Program.

GOLD IN PLANTS Recent experimental studies on Au uptake by plants indicate that nanoscale and larger phytonuggets can form in the xylem tissue of plants (Fig. 6). Although artificially large concentrations (several ppm) of Au were used in these experiments, it does indicate the propensity for Au to form elemental particles in vegetation. Illuviated phytonuggets may be important as nucleation sites for secondary Au particles to grow in the soil or carbonate profile.

References BRISTOW A.P.J., LINTERN M.J., & BUTT C.R.M. 1996. Geochemical expression of concealed gold mineralization, Safari Prospect, Mt Celia, Western Australia. CRC LEME 13R/Exploration and Mining Report 281R. (Reissued as Open File Report 104, CRC LEME, Perth, 2001). DART R.C., BAROVICH K.M. & CHITTLEBOROUGH D. 2005. 22nd International Applied Geochemistry Symposium, 2005, Perth, Australia. Poster presentation and Abstracts volume.

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Geological Society of Australia Abstract No.87

1. Vegetation: Gold is shed from leaves, bark, dropped branches. Au up to 3.6 ppb. 3. Topsoil: Gold (organo-) complex adsorbed to clay particles. Topsoil contains organic matter concentrated in Au. Au up to 5.5 ppb in fine fraction.

2. Litter: Decay of biological material, releases Au to topsoil. Au in original complex (as in vegetation) or forms new complex. Au up to 1.7 ppb 4a. Calcareous rhizomorph: Soil moisture removed by transpiring vegetation. Calcium precipitates as carbonate as solubility exceeded. Complexed Au undergoes similar precipitation. Au up to 9.7 ppb.

4b. Lateral roots: Adsorb water, nutrients and metals (including Au). Some Au leached down through sand recycled back into plants.

5a. Calcrete: Zone of concentration of carbonate and Au. Gold in calcrete residually concentrated from remnants in saprolite and from vegetation. Major source of gold in vegetation. Au up to 36 ppb.

Remnant Au in quartz (saprolite)

5b. Tap-vertical roots: Absorbs water, nutrients and metals (including Au) W^ter taken up from here typically during dry periods. Gold adsorbed from calcrete and/or saprolite directly Au up to 1-2 ppb.

Figure 5. Gold in the sand dune at Barns and a model for its accumulation LINTERN M.J. (Compiler) 2004. The South Australian Regolith Project Final Report - Summary and Synthesis. CRC LEME Open File Report 156. 41 pp + 81 pp Appendices LINTERN M.J. 2007. Vegetation controls on the formation of gold anomalies in calcrete and other materials at the Barns Gold Prospect, Eyre Peninsula, South Australia. GEEA 7: 249 - 266). LINTERN M.J. & BUTT C.R.M. 1997. The use of calcrete as a sample medium for gold exploration. Kalgoorlie '97: An International Conference on Crustal Evolution, Metallogeny and Exploration of the Yilgarn Craton - An Update. AGSO Extended Abstracts Record 1997/41: pp 229-234. LINTERN M.J. & SHEARD M.J. 1998. Regolith studies related to the Challenger Gold Deposit, Gawler Craton, South Australia. Geochemistry and stratigraphy of the Challenger Gold Deposit. CRC LEME Restricted Report 78R, 2 Volumes. 95 pp + Appendices (un-paginated). (Reissued as Open File Report 78, CRC LEME, Perth, 1999). LINTERN M.J., TAPLEY I.J., SHEARD M.J., CRAIG M.A., GOUTHAS G. & CORNELIUS A.J. 2003. Regolith studies at Edoldeh Tank (ET) Gold Prospect, Gawler Craton, South Australia. CRC LEME Open File Report 150., 2 Volumes. 167 pp + 225 pp Appendices + map.

EDGECOMBE D. 1997. Challenger Gold Deposit. MESA Journal A, 8-11. GIBBONS L. & LINTERN M. 1998. Regolith geology and geochemistry at Old Well gold prospect, Gawler Craton, South Australia. Program and Abstracts, Regolith 98 (Kalgoorlie). CRC LEME, Perth, p39. {Posterpresentation). GRAY D.J., LINTERN M.J. & LONGMAN G.D. 1990. Chemistry of gold in some Western Australian Soils. CSIRO Division of Exploration Geoscience, Perth, Restricted Report 126R, 62 pp. (Reissued as Open File Report 68, CRC LEME, Perth, 1999) GRAY D.J. & LINTERN M.J. 1993. Further aspects of the chemistry of gold in some Western Australian soils. CSIRO Division of Exploration Geoscience, Perth, Restricted Report Number 391R, 55 pp. (Reissued as Open File Report 34, CRC LEME, Perth, 1998). GRAY D.J. & LINTERN M.J, 1998. Chemistry of gold in soils from the Yilgarn Craton, Western Australia. Regolith 96 Conference - The State of the Regolith. Geological Society of Australia Special Publication 20, 209-221 LINTERN M.J. 1989. Study of the distribution of gold in soils at Mt Hope, Western Australia. CSIRO Division of Exploration Geoscience, Perth, Restricted Report 24R, 40 pp. (Reissued as Open File Reported, CRC LEME, Perth, 1999).

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in Australia. Goldschmidt Conference Abstracts 2007. pA831. SCHMIDT MUMM A. & REITH F. 2007. Biomediation of cicrete at the gold anomaly of the Barns prospect, Gawler Craton, South Australia. Journal of Geochemical Exploration 92, 13-33. SHEARD M.J., LINTERN M.J., PRESCOTT J.R. & HUNTLEY D.J. 2006. Great Victoria Desert: new dates for South Australia's ?oldest desert dune system. Department of Primary Industries and Resources, South Australia. MESA Journal 42, 15-26. SKWARNECKI M., SHU LI & LINTERN M.J. 2001. Geochemical dispersion in the Olary District, South Australia. CRC LEME Restricted Report 156R, 2 Volumes. 78 pp + Appendices (unpaginated). (Reissued as Open File Report 113, CRC LEME, Perth, 2001).

LINTERN MJ., SHEARD M.J. & CHIVAS A.R. 2006. The source of pedogenic carbonate associated with gold-calcrete anomalies in the western Gawler Craton, South Australia. Chemical Geology, 235: 299-324. LINTERN M.J., VERRAL M.R. & BELTON D.X. 2007. Gold uptake in Australian plants - a preliminary experimental study. 23rd International Applied Geochemistry Symposium, 2007, Oviedo, Spain. Poster presentation and Abstracts volume. MCENTEGART L.B. & SCHMIDT MUMM A. 2005. Gold mobility within dune systems on the Barns Prospect, Wudinna, South Australia: a partial extraction approach. In: I.C. Roach (editor). Regolith 2004 - Proceedings of the CRC LEME Regional Regolith Symposia, CRC LEME, Perth, Western Australia, pp 235-240. REITH F. & SCHMIDT MUMM A. 2007. Microbially mediated formation of gold in calcrete anomalies

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SPECTRAL MAPPING MINERAL ALTERATION IN THE CENTRAL GAWLER GOLD PROVINCE - TARCOOLA CASE STUDY A.J. Mauger and J.L. Keeling CRC LEME, Geological Survey, Primary Industries and Resources South Australia, PO Box 1671, Adelaide, South Australia, 5001

INTRODUCTION The central Gawler Craton Proterozoic gold province in South Australia extends over an area of some 60,000 km^ and incorporates known gold deposits and new prospects (Fig. 1) that appear to have a common genesis (Budd, 2002; Drown, 2003; Ferris and Schwarz, 2003). Gold mineralisation, largely as Au±Ag in structurally controlled quartz veins, formed at --1590 Ma, most probably from fluids mobilised during widespread intrusion of Hiltaba Suite granite. Alteration mineralogy is typically sericite, chlorite and pyrite. The province extends over remote, semi-arid terrain where the Proterozoic bedrock is often deeply weathered and, in places, buried by thin sediment cover. Additional exploration methods are needed to support current techniques of geophysical identification of prospective shear zones in close proximity to undeformed granite, with follow up 'calcrete' geochemical sampling. Satellite and airborne spectral methods provide a rapid, regional-scale approach to map areas of weathered bedrock and potentially, also the distribution of alteration minerals formed during hydrothermal activity. Hyperspectral data, in visible to shortwave infrared (Vis-SWIR) spectral range acquired over the historic Tarcoola Goldfield, 650 km northwest of Adelaide, were interpreted to reveal patterns of alteration mineralogy with potential to provide vectors for Au exploration (Mauger et a!., 2007). HyMap, HyLogger^^, PIMA and ASD Field Spec Pro instruments were used to collect data on surface and underground samples.

Figure 1. Au deposits and prospects within outline of central Gawler Proterozoic gold province

Mesoproterozoic age (1582±5 Ma) and equated with the 'Hiltaba event' (Budd and Fraser, 2004). A systematic zoning of alteration minerals is associated with Au mineralisation in Paxton Granite at the Perseverence prospect. This includes chloritisation of ferromagnesian minerals and sericitisation of plagioclase that is most intense in close proximity to quartz veins carrying high sulphide and Au contents (Budd and Fraser, 2004). At the historic Tarcoola Blocks workings of the goldfield, gold was mined mostly from quartz veins that cross cut the sedimentary transition from Fabian Quartzite to Sullivan Shale. The lithological layering may have provided the necessary competency contrast to produce open fractures under stress, and the carbonaceous shale interbeds a chemically reactive host to precipitate sulphide and Au from solution (Potma and Bastrakov, 2006).

GEOLOGY The historic gold workings at Tarcoola are largely confined to quartz veins that cut across Fabian Quartzite and Sullivan Shale members of Palaeoproterozoic Tarcoola Formation (age --165617 Ma) (Fig.2). Recent mineral exploration has identified additional Au resources in quartz veins on the Perseverance fault trend in the underlying Paxton Granite (age -1715 Ma). The Palaeoproterozoic rocks are intruded by diorite dykes collectively known as Lady Jane Diorite of

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Geological Society of Australia Abstract No. 87

I Younger cover sediments Lady Jane Diorite

Strike and dip of bedding

Sullivan Shale Member

Fault

Fabian Quartzite Member

Thrust

Peeia Conglomerate Member

+ I Paxton Granite

-k-

Antiform Tarcooia Block Mining Leases

Figure 2. Geology of Proterozoic outcrop at Tarcooia Goldfield showing area of the main Tarcooia Blocks workings and Perseverance and Last Resource prospects, on the Perseverance fault trend

SPECTRAL MAPPING

The same mineral also maps a broad area in Paxton Granite extending westerly from an outcrop of Lady Jane Diorite and terminating against the Perseverance Fault trend. Spectra of field samples confirmed that the mineral is illite. Samples collected from adjacent areas in Tarcooia Formation sediment, but showing different spectral response, (Fig. 3) indicate the presence of illite in both samples but confirm a difference in "crystallinity" reflected in a deeper 1900nm water absorption feature in the illite of apparent lower crystallinity (Fig. 4). A correlation was established between the "crystalline" illite, as defined by a weak water absorption feature at 1900nm, and phengite, the Al-depleted, fine-grained muscovite (sericite) associated with mineralisation. "Crystalline" illite at the surface is effectively the weathered product of sericite in areas with high muscovitephengite content in the underlying bedrock. Two environments display the more crystalline variety of illite: 1) mica rich sedimentary units and, 2) cross-cutting zone of alteration, mostly in Paxton Granite, that include an intrusion of Lady Jane Diorite, possibly the heat source for Au mobilisation. The Perseverance Fault and the

Spectral data over the goldfield were acquired using airborne HyMap system of HyVista Corporation (for specifications refer connpany website www.hwista.com/main.htmn. A straightfonA^ard decorrelation stretch was used to highlight variation in the wavelengths responsive to AI(OH) hydroxyl bonds (2171, 2181, 2205 nm) (Fig. 3). Spectral variations displayed in the image were field checked and samples collected for further spectral analysis using ASD Field Spec Pro and PIMA. Polished thin sections of selected samples were prepared for petrology and microprobe analysis. The effect of weathering on surface mineralogy, depth of weathering, and mineral alteration patterns in fresh rock were investigated by spectral logging drill core from 12 holes in the Perseverance prospect using the CSIRO HyLogger"^^ spectral core scanner (Huntington et al., 2004).

RESULTS

From the airborne HyMap data, one AI(OH) group mineral, discriminated from the spectral data, shows an association with the prospective horizon in the Tarcooia Formation sediments.

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Figure 3. HyMap image of historic Tarcoola Goldfield showing alteration defined by AI(OH) species. Kaolin arrowed, crystalline illite (dark grey), smectite (pale grey) (sericite-rich road rubble on tracks appears dark grey) References BUDD A.R. 2002. Hiltaba Suite magma composition: a regional-scale guide to location of Cu-Au versus Au-only mineralization. Proceedings Gawler Craton State of Play Conference, Adelaide, December 2002. Department of Primary Industries and Resources, South Australia (available on CD). BUDD A.R. & FRASER G.L. 2004. Geological relationships and "^W/^^AR age constraints on Au-mineralisation at Tarcoola, central Gawler gold province, South Australia. Australian Journal of Earth Sciences 51, 685-699. DROWN C.D. 2003. The Barns gold project. Primary Industries and Resources, South Australia, MESA Journal 28, 4-9. FERRIS G.M. & SCHWARZ M. 2003. Proterozoic gold province of the central Gawler Craton. Primary Industries and Resources, South Australia, MESA Journal 30, 4-12. HUNTINGTON J., MAUGER A.. SKIRROW R., BASTRAKOV E., CONNOR P., KEELING J., COWARD D.. BERMAN M., PHILLIPS R., WHITBOURN L. & HEITHERSAY P. 2004. Automated mineralogical of core from the Emmie Bluff, iron oxide copper-gold prospect. South Australia. PACRIM 2004 Congress, Adelaide, AusIMM Publication Series no. 5/2004, 223-230. MAUGER A.J., KEELING J.L. & HUNTINGTON J.F. 2007. Alteration mapping of the Tarcoola Goldfield (South Australia) using a suite of hyperspectral methods. Applied Earth Science (Transactions, Institute of Mining and Metallurgy, B;116, 2-12. POTMA W. & BASTRAKOV E. 2006. Tarcoola modelling: Predictive targeting outcomes. CSIRO Exploration and Mining, Report P2006/119.

Figure 4. ASD spectra from surface samples showing the spectral differences between two varieties of illite Bonanza gold zone occur on the margins of the alteration zone. Outside this zone, feldspar in Paxton Granite is not altered to mica and weathers to give kaolin at the surface (Mauger et al., 2007). Below ground the HyLogger™ clearly mapped the depth of weathering by the presence of dominant kaolinite and iron oxide (Fig. 5). Where sericite alteration is high, mica/illite persists throughout the weathered zone to the surface. Supergene Au enrichment within the weathered profile correlates with the presence of smectite or alunite, and an increase in Fe^"^ goethite content. Below the supergene zone hematite, phengite, chlorite and siderite showed associations with elevated Au values (Fig. 5).

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Figure 5. Histograms showing semi-quantitative distributions of key mineral assemblages down drillholes from Perseverance prospect a) TD009, b) TD001, c) GP004D. Note: Smectite, Fe^^ Goethite in supergene Au zone in a); Kaolinite, Iron oxide defines weathered zone in b); Phengite and Au association at ~120m depth in c).

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BIOGEOCHEMICAL AND GEOCHEMICAL EXPRESSIONS OF URANIUM PROSPECTIVITY ACROSS THE FOUR MILE CREEK CATCHMENT, SOUTH AUSTRALIA. J.M.P. McMAHON and S.M. HILL CRC LEME and School of Earth and Environmental Sciences, University of Adelaide, Australia 5005.

available to the mineral explorer or environmental geochemist. Stream sediment geochemistry is a popular geochemical exploration method based on the premise that sediments contained in the stream or drainage basin will represent a composite sample of rock fragments and overburden from a catchment system further upstream of the sample site (Ottesen and Theobald, 1994). Therefore, any anomalous chemical characteristics of a sample may reflect an unusual chemical situation in the drainage basin, such as those directly related to the leaching and erosion of orebodies, which can be used to identify the setting in which a mineral deposit may occur (Ottesen and Theobald, 1994). In many cases, this geochemical approach provides information on major lithologic characteristics from a catchment highlighting areas for further investigation and mineral exploration (Ottesen and Theobald, 1994; Horeefa/., 2005). Many studies in the northern Flinders Ranges have used stream sediment reconnaissance with the aim to identify geochemical anomalies from catchment areas (Ottesen and Theobald, 1994; Whitehead, 1966; Hall, 1973; Carthew, 1973, 1974; Shackleton, 1974). Generally, studies conducted in this region were only conducted on a smaller, local scale, and the methods used by each program varied, making comparisons between results more difficult (Hall, 1974). Studies by Whitehead (1966), Carthew (1973, 1974), Shackleton (1974) and Hall (1974) supported the use of <80 pm size fraction, believing it to be more precise and the most likely to detect anomalous readings. Whilst these do confirm anomalous assay values, it is likely that these results mainly reflect the lithology of the area and not directly relate to mineralisation occurrences (Hall, 1974). Previous stream sediment surveys from the region however, have been successful at detecting U anomalies at sites such as the Gunsight Prospect within the ranges (Carthew, 1974). One way to achieve regionally representative geochemical expression is by amalgamating assay results from a population of

INTRODUCTION Despite the wide adoption of regional geochemical sampling media in mineral exploration and environmental geoscience programs, there are typically limited regional orientation studies of these media to test their characteristics and abilities of expressing mineralisation. The ability to efficiently provide representative regional geochemical expressions is critical for regional mineral exploration, environmental geochemistry and baseline geochemical surveys (Bowie, 1972; DeCaritat, 2005). Traditionally, stream sediment geochemistry has been used in mineral exploration programs, such as the regional stream sediment surveys of the northern Flinders Ranges region by North Flinders Minerals (Carthew, 1973, 1974). More recently, Geoscience Australia has been using the fine-grained sediment fractions from alluvial sediments to provide a catchment-scale regional geochemical baseline expression (DeCaritat, 2005). Even these techniques can be challenged by providing a regionally representative geochemical expression, and usually require a major preliminary orientation study characterising ideal sample types, size fractions and sample landscape settings. Other regolith and landscape geochemical techniques, such as soil and calcrete sampling typically host local-scale (<1 km scale) geochemical heterogeneity and variation, therefore making their application ideal for tenement and prospect-scale exploration, but limited in providing a robust regional representation at wide sample spacings (>1 km scale). Similarly, phyto-exploration has major advantages for tenement to prospect-scale exploration, in particular an ability to provide a penetrative geochemical signature through transported cover (Hill, 2004). However the application of phyto-exploration techniques at the regional scale is challenged because of the need to provide a chemical representation of large areas, typically beyond the size of an individual plant. Besides traditional stream sediment sampling programs there appear to be few other regionally viable sampling media options

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mineral exploration for uranium, but it can be compared to a biogeochemical sampling medium.

local samples. The greater the number of local samples that are taken across an area and combined, a regional geochemical expression should become more representative. The disadvantage of this approach however is that it is time and assay intensive, involving increased field sampling time and assay production to provide a more regionally representative result. In contrast, a major objective of most regional surveys is efficient regional representation. One potential alternative is to consider the scat samples from herbivores that have been grazing a large number of plants across a defined region, or home-range. There have been extensive ecological and zoological studies on macropod species in semiarid south-eastern Australia (Dawson, 1995; Dawson and Ellis, 1994; Croft, 1991a, 1991b; McCullough and McCullough, 2000). Their homerange behaviour in semi-arid conditions has been well defined, with the euro and red kangaroo defined as sedentary (Priddel et a!., 1988, Clancy and Croft, 1990; Croft, 1991a, 1991b; Dawson, 1995; McCullough and McCullough, 2000). A preliminary study from the Broken Hill region (Hill, 2004) suggests that plant chaff from within macropod scats have the potential to provide regional biogeochemical expressions from the grazing home-range of the animals. Hill (2004) sampled macropod scats around the Broken Hill area for biogeochemical analysis. Results from this study included high assays for elements such as Pb, Cd and Zn in the vicinity of the Broken Hill Line of Lode. This therefore shows potential for macropod scats to be used in the detection of mineralisation and/or contamination within regional chemical sampling. It is not yet certain however, whether the scats would have reflected a natural chemical footprint or the presence of any previous mining or smelting operations (Hill, 2004). This study therefore aims to characterise and compare two regional environmental and mineral exploration sampling media: stream sediment geochemistry and macropod scat biogeochemistry. Samples were collected west of the Beverley Uranium Mine, South Australia; across an upper tributary headwater catchment of the Four Mile Creek drainage system. The study area provides a stable habitat for 3 large species of macropod: red kangaroo {Macropus rufus)] euro (M. robustus); and, the occasional western grey kangaroo (M. fuliginosus). These species graze the shrubs and forbs overlying known mineralisation on the plains and the vegetation growing above U-rich bedrock in the ranges. The results of this study therefore will not only have major implications for the use of stream sediment surveying as a means of

STREAM SEDIMENT GEOCHEMISTRY INTERPRETATION Assay results of 10 elements including Au, Ce, Cu, Hf, Pr, Th, U, V, Y and Zr were chosen for mapping and interpretation due to their strong correlation with U-mineralised areas. The comparison of three fraction sizes within the stream sediment samples indicated that: • The coarse (>300 |jm) fraction provided a poor expression of mineralisation, as it is primarily derived from weathered bedrock (Mazzucchelli, 1994), where it is transported from the headwaters of the catchment by ephemeral creek systems downstream and onto the braided alluvial plains. • In both the medium (79 - 300 |jm) and fine (<79 |jm) size fractions, U has very high assays from the headwaters of the catchment with values decreasing exponentially with distance down the catchment and onto the braid-plain. • The fine fraction had a more uniform decrease, whereas the medium fraction tends to detect slightly higher values across the braid-plain, such as across the Four Mile west mineralisation (Fig. 1, Fig. 2).

•

This indicates that the medium size fraction detects a higher anomaly to background contrast that the fine fraction does not detect. This is perhaps due to the input of wind blown aeolian material (Mazzucchelli, 1994). All stream sediment fractions however, show a strong derivation and dispersion signature originating in the bedrock dominated catchment headwaters.

MACROPOD SCAT BIOGEOCHEMISTRY INTERPRETATION Results are described here for the same 10 elements (Au, Ce, Cu, Hf, La, Mo, Th, U, V, Y, Zr) as were considered for the stream sediments. The element Mo however was chosen as a replacement of Pr due it not being included in the analytical suite for the macropod scats. The macropod scat geochemistry did not successfully represent areas or regions that may contain secondary U mineralisation across the element suite. This may be due to the small number of scat samples derived from this part of the study site, or else it being comprised of

Geological Society of Australia Abstracts No. 87

vegetation that has a shallow root system, and therefore did not take up elements near zones of buried mineralisation. However, the very high assay value (20.98 ppm) for U in the catchment indicates that macropod scat sampling methodology has good potential to detect anomalous values associated with primary mineralisation in comparison with background ones, especially in this semi-arid environment (Fig. 3). This can be justified by the high assay values also being detected from various regional samples, which are also comprised of known primary U mineralisation, such as Gunsight (7.46 ppm), Radium Ridge (4.84 ppm) and Streitberg Ridge (6.76 ppm). These regional samples, have been sampled in close proximity to vegetation that was sampled by Nemanis and Hill (2006). Vegetation from Eucalyptus gillii and Eucalyptus intertexta yielded high assay values of 6.59 ppm and 6.49 ppm respectively, at Radium Ridge (Nemanis and Hill, 2006). These are very comparable to the values detected in the macropod scat assays. Assay results for vegetation at the Streitberg Ridge and Gunsight locations were much lower than those found in the macropod scats (Nemanis and Hill, 2006). This may be due to the fact that the macropod species which inhabit the area have foraged on vegetation to a greater degree than what was sampled in these locations, also incorporating a diverse amount of vegetation species into their diet. Through the implementation of a particular macropod species' daily home-range, which varies from 600 m^ in euros to 1500 m^ in red kangaroos (Croft, 1991a, 1991b; Dawson, 1995; McCullough and McCullough, 2000), the distance surrounding the site from which the scat was sampled forms a halo in which primary mineralisation is likely to be expressed by the vegetation within this area.

IMPLICATIONS FOR MINERAL EXPLORATION The Four Mile U mineralisation is a sandstone hosted roll-front type 6 km east of the Beverley U mine, defined through drilling programs in which two main areas of mineralisation are outlined and identified. It is possible that further U mineralisation remains to be discovered in the Four Mile area. Due to steep and high topographic relief restricting access to the adjacent northern Flinders Ranges, alternative exploration methods are needed to further detect and establish the extent of U mineralisation in this region. This study has highlighted that the geochemical sampling method depends on the

Sprigg Symposium, Adelaide, November 2007

sampling scale of the program. Regional baseline programs would probably benefit from using the fine fraction size, especially if less samples are to be taken across a larger area and would best detection primary mineralisation across a broad area. It would also be useful if exploration is taking place in areas of high topographic relief, and sieving is undertaken on site. However, tenement to prospect scale exploration would probably benefit from the use of the medium (79 300 |jm) fraction, as it gives the largest assay value range, and is likely to be more locally derived than the fine fractions. Biogeochemistry, in particular phytoexploration has been useful in regional-scale prospecting for mineralisation (Hill, 2004; Dunn, 2007). This study further shows the potential for semi-arid macropod species to provide a singlesample regional biogeochemical expression of areas prospect for U mineralisation. The discrete nature of the anomalies expressed in this study demonstrated that macropod scat sampling can be an effective sampling medium and has a good potential to detect and contrast highly anomalous to background values in high topographic relief areas and can take place at a sampling spacing of greater than 200 metres. One sample may therefore express a significant chemical signature derived from a combination of plant individuals. Through the knowledge and understanding of macropod home-range, prospect scale exploration programs can then be devised and executed in areas which express significant geochemical signatures. There are many advantages of macropod scat biogeochemistry: • They make an effective pilot investigation into a prospective region, with macropod home range varying between 600 and 1500 m^. • The initial sampling collection methodology simple and cost effective. One person can collect many samples using only snap-seal bags and nitrile or powder free latex gloves across a large distance. The processing is also cost effective relative to drilling. • It is environmentally feasible, with no disturbance to environmental processes and no disturbance to environmental or culturally sensitive areas. The extension of results from macropod sampling into phyto-exploration within the macropods home-range will then be advantageous at locating anomalies beneath the surface, and their sampling may complement regional stream sediment programs, or may be more useful in areas such as dune fields where there are fewer stream channels to sample.

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Sprigg Symposium, Adelaide, November 2007

353500

354500

355500

356500 '

357500

358500

Legend Uranium (Medium) value: ppm Four Mile mineralisation

® # 0 ^

4.5-10.9 11.0-38.0 38.1 -72.2 72.3-100.0

Grid north 1 0 1

Meters

750 I

3,000

1,500

356000'^

357000

Figure 1. Geochemical maps of U assay values in the medium (79 - 300 |jm) sized stream sediment fraction.

120

100 80

? s

60 40 %

20 0

1000

2000

3000

4000

« 5000

6000

7000

Sample distance downstream (m)

Figure 2. Geochemical stream sediment U assay variation with distance (m) along the study channel in the medium sized stream sediment fraction.

357500

Legend Uranium (Macropod Scat) value: ppm ( 3

Four Mile mineralisation

( ( |[ f

0.06-1.97 1.98 - 3.96 3.97-7.61 7.62 -20.98

Grid north t

0 I

Meters

750 L

1,500

Figure 3. Biogeochemical map of U assay values in nnacropod scat media.

358500

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Sprigg Symposium. Adelaide, November 2007

MAZZUCCHELLI R. H. 1994. Drainage geochemistry in arid regions. In: Hale M. & Plant J. A. eds. Handbook of Exploration Geochemistry, Volume 6: Drainage Geochemistry. pp 379-414. Elsevier, Amsterdam. MCCULLOUGH D. R. & MCCULLOUGH Y. 2000. Kangaroos in outback Australia. Columbia University Press. New York. NEMANIS M. J. AND HILL S. M. (2006). Plant Biogeochemical Expression on Uranium Mineralisation in Australia: Research Outline and Preliminary Results. In: Fitzpatrick R. W. & Shand, P. eds. Regolith 2006: Consolidation and Dispersion of Ideas. CRC LEME, Bentley. OTTESEN R. T. & THEOBALD P. K. 1994. Stream sediments in mineral exploration. In: M. Hale and J. A. Plant (eds). Handbook of Exploration Geochemistry, Volume 6: Drainage Geochemistry, pp 147-184. Elsevier, Amsterdam. PRIDDELL D., SHEPHERD N., & WELLARD G. 1988. Home ranges of sympatric red kangaroos, Macropus rufus, and western grey kangaroos M. fuliginosus, in Western New South Wales. Australian Journal of Wildlife Research 15: 405411

References BOWIE 8. H. U. 1972. The status of uranium prospecting. In: S.H.U. Bowie 8. H. U., Davis M., & Ostile D. eds. Uranium prospecting handbook, pp. 1-16. The Institution of Mining and Metallurgy, London. DeCARITAT P. 2005. Using groundwater to vector towards mineralisation under cover: The Curnamona Province. In: Roach I. C ed. Ten Years of CRC LEME, pp. 35-37. CRC LEME, Bentley. CARTHEW 8. J. 1974. Geochemical Survey Paralana - Carthew Valley (PCV Area). Open File Envelope 02034. 9: 720-732 CARTHEW 8. J. 1974. Geological mapping and geochemical appraisal of an area extending from brindana gorge to parabarana hill. SMLs 704 705, South Australia. Open File Envelope 14: 931-961 CLANCY T. F. & CROFT D. B. 1990. Home range of the common wallaroo, Macropus robustus erubescens, in far western New South Wales. Australian Wildlife Research 17, 659-173. CROFT D. B. 1991 A. Home range of the red kangaroo, Macropus rufus. Journal of Arid Environments 20, 83-98. CROFT, D. B. 1991b. Home range of the euro, Macropus robustus erubescens. Journal of Arid Environments 20, 99-111. DAWSON T. J. 1995. Kangaroos, Biology of the Largest Marsupials. UNSW Press, Sydney, Australia DAWSON T. J. & ELLIS B. A. 1994. Diets of mammalian herbivores in Australian arid shrublands: seasonal effects on overlap between sheep and rabbits and on dietary niche breadths and electivities. Journal of Arid Environments 26: 257-271. HALL J. S. 1973. General Comments on the Stream Sediment Geochemistry (Cu, Zn) in the Northern Flinders Range Area of South Australia February 1974. Open File Envelope 02034. 6: 379-433. HILL S. M. 2004. Biogeochemical sampling media for regional-to prospect-scale mineral exploration in regolith-dominated terrains of the Curnamona Province and adjacent area in western NSW and eastern SA. In: Roach I. C. ed. Regolith 2004. pp 128-133. CRC LEME, Bentley. HORE S., FIDLER R., MCINNES R. & RAGLESS J. 2005. Mount Painter Geochemistry - an old terrain revisited with new science. MESA Journal 38: 8-14.

SHACKLETON W. G. 1974. Stream sediment orientation survey for copper in the northern Flinders Ranges, South Australia. Salisbury College of Advanced Education. Occasional Paper No 4. Salisbury C A E . WHITEHEAD R. C. 1966. Report on Paralana concession special mining lease No. 112, South Australia. Open File Envelope 663.

ACKNOWLEDGEMENTS I would like to thank Heathgate-Resources for their consistent support throughout the year and also for providing us with accommodation during our field trips. The funding of this honours project through CRC LEME and PIRSA is very much appreciated. Big thanks go to the Adelaide Uni CRC LEME community for helpful honours advice, 'tricks of the trade' shortcuts for those hard to master geochemical computer programs and just because you're all awesome! This study greatly benefited from the involvement of the ever-helpful Steve More from PIRSA, not only for his diverse array of geological knowledge but also for entertaining field discussions and expertise at northern Flinders Ranges four wheel driving.

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Geological Society of Australia Abstract No. 87

PLANT BIOGEOCHEMICAL EXPRESSION OF THE FOUR MILE URANIUM MINERALISATION, FROME EMBAYMENT, SOUTH AUSTRALIA Michael Neimanis^ ^ Steven HilP ^ and Steve Hore^ ^ Cooperative Research Centre for Landscape Environments and Mineral Exploration ^Geology and Geophysics, The University of Adelaide, Adelaide, South Australia ^PIRSA, Geological Survey, GPO Box 1671, Adelaide SA 5001

of barren sandstone cover was detected using plant biogeochemistry in Canada (Dunn, 1981). Blogeochemical exploration at the Four Mile Prospect offers further (compounded) complications, namely extensive cover and a similarly difficult environment which plants must survive. However, significant improvements in analytical techniques since these studies were undertaken could perhaps prompt a re-evaluation of the biogeochemical method for uranium exploration in Australia. This research represents a component of a PhD project undertaken by the principal author at the University of Adelaide.

INTRODUCTION The impediment to mineral exploration presented by transported and/or extensively weathered overburden is common in Australia, whereby regolith masks underlying mineralisation. South Australia's Frome Embayment offers such an example; a world-class uraniferous province with significant transported and weathered cover. Both the Beverley and adjacent Four Mile secondary uranium deposits sit below several sedimentary sequences, often at depths in excess of 100 metres. Developing and refining techniques that can assist in overcoming such an impediment are of obvious importance. This paper introduces and outlines the use of phytoexploration at the Four Mile U Prospect, adjacent to the Beverley Mine and Northern Flinders Ranges. The use of plant biogeochemistry for mineral exploration, or phytoexploration, has had a successful history (e.g. Brooks, 1983), despite its relatively limited uptake in Australia. Phytoexploration has been successfully utilised in uranium exploration, although to date this success has predominantly been found outside of Australia. However, increased uranium content in vegetation growing over mineralisation has been reported at the Ranger One and Jabiluka uranium deposits. Northern Territory (Cruikshank and Pyke, 1986; Rowntree and Mosher, 1976). Despite any such successes, phytoexploration for uranium has largely been abandoned in Australia. While no accounts of phytoexploration for uranium in settings directly analogous to the Frome Embayment setting have been published, similar studies point to its potential for success. Among the earliest accounts. Cannon (1960) famously used vegetation surveys to indicate uranium mineralisation in the semi-arid Colorado Plateau, while plant biogeochemistry was similarly successful in an arid region of the Soviet Union, as reported by Malyuga (1963). Neither of these settings were of significant depth. Alternately, uranium mineralisation below 150 m

GEOLOGICAL SETTING Regional setting A useful summary of the regional geological setting and pertinent literature is offered by McKay and Miezitis (2001). The Beverley - Four Mile uranium mineralisation system sits to the east of the Mount Painter inlier in the Frome Embayment, a southern portion of the Callabonna Sub-basin. In this section of the sub-basin, Tertiary sediments (Eyre Formation equivalent), typically angular, poorly sorted sands with clay and silt, were deposited in palaeochannel systems. These Early Palaeocene-Late Eocene channels were disconformably overlain by Namba Formation sediments (Miocene). While the Beverley Deposit is hosted in younger Namba Formation sands, the Four Mile system is found in Eyre Formation sediments.

Mineralisation The secondary uranium mineralisation of the Four Mile Prospect is contained in reduced palaeochannel sandstone. Uranium was transported either as detrital rock and mineral fragments or in solution; in both cases the presence of reducing, alkaline plant matter is vital for its precipitation. Primary mineralisation in basement rocks of the Mount Painter Complex provided the source of uranium for the system.

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Geological Society of Australia Abstract No. 87

The subsequent deposition of clays and silts effectively contained the system as a discrete aquifer. Mineralisation is divided into two zones, Four Mile West and Four Mile East, which appear to be discontinuous. The depth to mineralisation at Four Mile is approximately 130 m.

METHODS Field Sampling Program Two target species were chosen for sampling prior to undertaking the survey, river red gum (Eucalyptus camaldulensis ssp. obtusa), and inland tea tree/paper bark {Melaleuca glomerata). These species were chosen as they best suited criteria similar to that discussed by Brooks (1983), including: • the most ubiquitous species available in the sampling area; • most inveterate species available, and; • prior success using them in biogeochemical surveys, e.g. Hill and Hill (2003). Other species sampled include: • Rock emubush - Eremophila freelingii; • Dead finish - Acacia tetragonophylla; • Prickly wattle - Acacia victoriae; • Rosewood - Electryon oleifolium; • Pearl bluebush - Maireana sedifolia, and; • Mulga - Acacia aneura. All botanical names are after Cunningham et al. (2003), except for Electryon oleifolium (changed since publication). The method used for field sampling is discussed by Hill (2002). The sampling program was undertaken in January 2007, with > 300 plant phyllode samples collected. Rainfall for the several months prior to sampling (late spring to summer) was negligible, giving rise to the assumption that the depth of water uptake by the plants was at a maximum due to surface soil desiccation. The two target species were essentially confined to watercourses and their headwaters. In larger creek sections which were laterally extensive, it was necessary to sample along transects that crossed creeks, rather than to sample along creek beds.

RESULTS Of the assayed river red gum and inland tea tree samples, all bar five (four and one of each species respectively) contained detectable amounts of uranium, suggesting that both species are able to detect uranium mineralisation over the Four Mile West Prospect. Samples taken further to the east appear to not overlie the Four Mile East Prospect as well, and provide less satisfactory results. Further analysis is required to establish what influence surficial uranium transport has on the uranium content of the plant tissues, as opposed to underlying mineralisation (Neimanis, in prep.). A summary of selected assay results for these two species is contained in Table 1. Table 1: Summary of selected plant biogeochemistry assay results for the Four Mile uranium prospect. Species assay range U ppm Th ppm Cu ppm Mo ppm Fe%

River red gum

Inland tea tree

<0.01 - 6.56 0.01-0.09 0.52-6.27 0.01 - 2 . 2 5 0.012-0.059

<0.01-0.76 0.02 - 0.28 1.17-7.90 0.15-4.19 0.018-0.105

One other notable assay includes 800.2 ppm Sr in a Rosewood sample. Follow-up sampling is planned for autumn 2008, with a view to better constraining the spatial distribution of uranium biogeochemistry of the Four Mile system. Of particular interest is any differentiation in biogeochemical expression related to changes in catchment source rock, and to establish the extent of uranium transport downstream. References BROOKS R. R. 1983. Biological Methods of Prospecting for Minerals. John Wiley & Sons, New York. CANNON H. L. 1960. The development of botanical methods of prospecting for uranium on the Colorado Plateau. U.S. Geological Survey Bulletin, 1085-A. CRUIKSHANK B. I. & FYKE J. G. 1986. Biogeochemistry and soil geochemistry of the Ranger One, Number 3 Orebody, Australia. Uranium 3, 1-26. CUNNINGHAM G. M., MULHAM W. E., MILTHORPE P. L. & LEIGH J. H. 2003. Plants of Western New South Wales. Inkata Press, Melbourne. DUNN C. E. 1981. The biogeochemical expression of deeply buried uranium mineralization in Saskatchewan, Canada. Journal of Geochemical Exploration 15, 437-452.

Analytical Techniques After collection, samples were oven dried at 60°C for 48 hours in a laboratory at the Beverley mine. The dried samples were transported to the University of Adelaide for sorting and milling, prior to assay. Despite the fact that ashing of plant samples is known to greatly concentrate uranium content (Dunn, 1981), samples were not ashed prior to analysis. Milled samples were analysed for 53 elements using ICP-MS (group 1VE-MS) by Acme Analytical Laboratories, Vancouver, Canada.

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Geological Society of Australia Abstract No. 87

HILL L. J. 2002. Branching out into biogeochemical surveys: A guide to vegetation sampling. In Roach I. C. (ed) Regolith and Landscapes of Eastern Australia, 50-53. CRC LEME Perth. HILL S. M. & HILL L. J. 2003. Some important plant characteristics and assay overviews for biogeochemical surveys in western New South Wales. In Roach I. C. (ed) Advances in Regolith, 187-192. CRC LEME Perth. MALYUGA D. P. 1964. The Application of the Biogeochemical Method in the Exploration for Uranium under Desert Conditions. In Biogeochemical Methods of Prospecting. Consultants Bureau, New York.

MCKAY A. D. & MIEZITIS Y. 2001. Australia's uranium resources, geology and development of deposits. AGSO - Geoscience Australia, Canberra. NEIMANIS M. J. in prep. Phytoexploration of uranium mineralisation. PhD Thesis, University of Adelaide. ROWNTREE J. C. & MOSHER D. V. 1976. Case history of the discovery of the Jabiluka uranium deposits, East Alligator River Region, Northern Territory of Australia. Symposium on Exploration of Uranium Deposits: Proceedings of a Symposium, Vienna, 29 March-2 April 1976, Jointly Organised by the IAEA and NEA (OECD). International Atomic Energy Agency, Vienna.

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Geological Society of Australia Abstract No. 87

TERMITARIA AS REGOLITH AND LANDSCAPE ATTRIBUTES: A CASE STUDY FROM TITANIA AUPROSPECT, NT. A.E. Petts and S.M. Hill Cooperative Research Centre for Landscapes, Environment, and Mineral Exploration. School of Earth & Environmental Sciences, The University of Adelaide, Adelaide South Australia 5005.

INTRODUCTION Australian regolith geologists aim to understand the evolution and nature of the extensive transported sediments and weathered in situ material that are the products of past environments and which may potentially host mineralisation. With the aim of testing the effectiveness of termite mounds (termitaria) as indicators of subsurface geology, this research examines the interaction of mound-building termite species with specific landscape settings. In particular we focus on Nasutitermes .triodiae (N. triodiae) and show that these termitaria may be utilised as palaeosurface indicators by regolith scientists and mineral explorers alike. The presence of an N. triodiae mound within a sandplain otherwise dominated by D. rubriceps will be examined and discussed in relation to regolith-landform mapping conducted during fieldwork in October 2006. With the preference of mound-building termites to build the larger mounds in the valleys and plains of semi-arid to tropical regions, it is often observed that, through their excavations, termites bring to the surface remnant soils from previous landscape surfaces (Williams, 1968; Williams, 1978; Johnson et a!., 2000; Roquin et a!., 2001). It has been observed from fieldwork that mound-building termites selectively build their mounds within certain landscape settings and regolith units (Hill, pers comm.; Petts and Hill, 2005; Petts and Hill, 2006a). This abstract aims to highlight the potential use of 'geozoology', the study of animals and organisms in relation to their geological or geographical environment, in the semi arid savannah lands of the Tanami Desert, northern Australia.

Figure 1. Location of the Titania Prospect, NT.

successful discoveries of mineralisation buried beneath the extensive transported cover of the Tanami. It hosts an abundance and wide range of termitaria, and contemporary regolith studies in the area also help constrain many of the variables of the environmental setting. These include regolith-landforms (Worrall et a!., 2005; Worrall et a!., 2006) vegetation and phytoexploration expressions (Reid et al, 2006), hydrogeochemistry (Kirste, 2006), and the thickness of regolith and the nature of subsurface materials through both exploration drilling and geophysics. The area has an arid to semi-arid tropical climate with distinct wet and dry seasons (Bureau of Meteorology, 1984). The main rainfall occurs in the summer months, between November to March, averaging 357 and 459 mm, at Rabbit Flat and Tanami Downs, respectively. Mean maximum temperatures at Rabbit Flat of approximately 39° C are experienced in December, with corresponding winter temperatures 10-15 degrees cooler.

GEOLOGY & MINERALISATION

LOCATION & CLIMATE

The regional geology and tectonic setting of the Tanami region is described by Blake (1978), and more recently by Wygralak et al. (2001). The region consists of two major Precambrian tectonic units, the Granites-Tanami Block and the Birrindudu Basin (Blake, 1978). The oldest rocks are associated with the Granites-Tanami Block

The field site is located in the Northern Territory, proximal to The Granites Mine and Callie Audeposit. The Titania Prospect (Fig. 1) is an ideal field laboratory for testing the ability of termitaria from different termite species to express buried mineralisation. It represents one of the few

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Geological Society of Australia Abstract No. 87

from the Smoke Hills to the west. Previous 1:25k regolith-landform mapping by Hill identified the three dominant geomorphic processes in the Titania area as alluvial, colluvial and aeolian. Further mapping (Fig. 2) has further detailed the landscape setting of the field locality.

and include Lower Proterozoic metannorphosed and unmetamorphosed sedimentary and volcanic rocks (siltstone, arenite, greywacke, conglomerate, phyllite, schist, banded chert, amphibolite, basalt, ironstone and acid porphyry). Lower to mid-Proterozoic granites and acid volcanics and Birrindudu Basin sediments (arenites, siltstone, limestone, shale, sandstone, stromatolitic chert and conglomerate) are overlain by the Cambrian Antrim Plateau Volcanics and Late Cambrian shallower marine and terrestrial sediments (limestone, sandstone and mudstone). These Cambrian and Proterozoic rocks are unconformably overlain by flat-lying Cretaceous pebble conglomerates, sandstone and minor siltstone. The Tanami Region hosts a number of significant gold deposits, as described by Wygralak and Mernagh (2001). The largest deposit is Callie, which is characterised by sheeted vein sets in the hinges of folded carbonaceous rocks within the Palaeoproterozoic Dead Bullock Formation. Deposition of gold at Callie is interpreted to have occurred at a redox front where oxidised auriferous fluids encountered reduced graphitic sediments. Although Titania is located within the Killi Killi Formation it is speculated that there are similar structural and geochemical controls on the deposition of gold. The ore minerals include arsenopyrite, pyrite and free gold.

Figure 2. Simplified regolith-landform map of Titania Prospect, NT., highlighting the location of mineralisation in a zone of transition from alluvial to aeolian and colluvial sediments, within a depression surrounded by depositional plains. The star represents the site of interest.

VEGETATION & REGOLITHLANDFORM SETTING

TERMITARIA AS REGOLITH LANDSCAPE ATTRIBUTES

Large parts of the Tanami region are colonised by open savannah woodland with hummockgrass understory, mainly including spinifex {Triodia pungens and Plectrachne schinzii), Acacia spp., Grevillea spp., and Eucalyptus or Corymbia spp. Gibson (1986) provides a detailed report of vegetation species and flora assemblages in the region. Wilford (2000) describes the regolithlandform setting of the Tanami region in great detail. The major landform types include alluvial plain, playa plain, dune field, colluvial fan, colluvial depositional plain, pediment and erosional plain, rises (9-30 metres relief) and low hills (30-90 metres relief). Elevation ranges from 647-308 metres above sea level, with the region having very low relief overall, with over threequarters of the mapping area having slopes less than 0.5 degrees. At a tenement scale the Titania fieldsite flanks a major palaeochannel, mostly expressed in the contemporary landscape as a large alluvial floodplain and ephemeral swamps central and to the east of the mineralisation. The area is also affected by colluvial sheetwash deposits derived

Termitaria form one of the most distinctive attributes of the Tanami landscape; particularly in areas of thick transported cover, such as across the ephemerally flooded, buried palaeodrainage systems. Over 14 species of termitaria have been recorded from the Tanami (Watson et al., 1993). At the Titania Prospect at least 3 species of termite are represented within the area of the sampling grid. The grass-harvesting termites and their termitaria are the most distinctive and abundant, including the species from the genii Amitermes, Drepanotermes and Nasutitermes (Fig. 3). Amitermes termites typically build simple, columnar, conical termitaria up to 1.8 m tall, but mostly around or below 1 m. They are most abundant in areas prone to seasonal flooding, such as alluvial and sheetflow plains and ephemeral swamps throughout the study area. The long residence time of termitaria in the landscape (from tens to hundreds of years) reflects more the presence of thriving colonies, rather than the permanence of the mounds.

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Geological Society of Australia Abstract No. 87

Legend

Amitermes sppJ ^ ^ . , N. Tnodiae jumufitermes spp. Figure 3. Mound morphology of the dominant termite species at Titania Prospect: (A) D. rubriceps] (B) N. triodiae, and; (C) Amitermes spp.

Lee and Wood (1971) note that termite mounds, whether colonised or not, are subject to continuous erosion. Abandoned mounds are progressively destroyed by wind and rain erosion. Observing termites at Brock's Creek, N.T., Williams (1968) recorded rates of mound erosion for abandoned termite mounds. Tumulitermes hastilis mounds are eroded to near ground level in three years, whilst those of N. triodiae can be eroded in about ten years. The inversion of regolith profiles due to termite activity has also been observed in West Africa by Le Roux et al. (1991), with fine silty material being dispersed across the surface derived from soil horizons below a ferricrete duricrust.

OBSERVATIONS OF TITANIA PROSPECT

TERMITARIA

Figure 4. Distribution of N. triodiae at Titania Prospect, NT.

The slab-like indurated D. rubriceps mounds may be found within most colluvial and aeolian regolith units, but at Titania these 'pavement' mounds were confined to the aeolian units to the north and south of the deposit (Fig. 5).

Amrtpme^-^pp. and D. rubriceps

Although there has been region-wide mapping of the distribution of termitaria (Watson, 1993) throughout northern Australia, there has been little fieldwork conducted at a smaller scale, more suitable for understanding the relationship between termites and regolith-landscape setting. Previous work by Petts and Hill (2005) showed the potential of termitaria as indicators of regolithlandform setting, and possibly thickness of regolith cover. The example at Coyote Au-deposit identified mound-building species such as Amitermes spp. as preferring alluvial sediments and depression/depositional landforms, whereas D. rubriceps enjoyed the sandier, shallow-cover sediments to the north of the deposit. Similar distinctions can be made at Titania, such as the dominance of N. triodiae within alluvial depressions and depositional plains (Fig. 4) compared to D. rubriceps, which appears to favour sandplains and sand dunes, as mentioned earlier. This distribution reflects both the morphological and functional needs of the nest, as the tall, rounded and lobate N. triodiae mounds require silty material for their vast mounds - the mound also has evolved to its current form as an adaptation to seasonal flooding across these landscape units.

Cdluvial Outline of mineralisation 1500 m

Figure 5. Distribution of D. rubriceps, and Amitermes spp. At Titania Prospect, NT.

The nature of the regolith-landform mapping and termitaria sampling program employed in this study allowed for observation and recording of the termitaria assemblage along transects, which could then be correlated with regolith-landform unit. At the southern end of one of the transects, within an aeolian sand-plain unit covered by D. rubriceps mounds, a 3.5 metre tall N. triodiae mound was noted as particularly anomalous in

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Geological Society of Australia Abstract No. 87

The original discovery of mineralisation at Titania was based on a soil anomaly expressed through sandplain, despite the presence of transported aeolian and alluvial materials (Gibbons and Webb, 1997). Cathedral mounds such as the one described herein are constructed from materials derived from some surface materials, but mainly palaeosol and upper regolith profile silt and clay aggregates. Despite the transported, aeolian contemporary landscape setting, termitaria mounds with their long residence times in the landscape present a fresh sample of the local regolith geology and geochemistry, unlike the aeolian and alluvial sediments nearby.

the landscape (Fig. 6). Upon closer inspection, the mound was observed to be abandoned and damaged by fire, but still retained its immense height. Whilst the residence time of abandoned examples of these 'cathedral' termitaria have been recorded as tens of years, there is a very good example of these mounds lasting at least one hundred years in the landscape when occupied, along the Overland Telegraph Line. Therefore, the termitaria in particular must have been active within the last hundred years and only abandoned within the last ten years, within a very different surficial setting to the present one.

ACKNOWLEDGEMENTS This research has been conducted with the assistance of a CRC LEME and University of Adelaide Scholarship, and CRC LEME operating funds. Thanks must go to the researchers within the Tanami Collaboration Project; Lisa Worrall, Nathan Reid, Brad Pillans, Dirk Kirste, and John Joseph. A big thank you to Nigel Radford and Simon Bolster from Newmont Asia Pacific, and to Damian Honner from Newmont Asia Pacific for support in the field. References ANDERSEN A. & JACKLYN P. 2000. Termites of the Top End - Engineering marvels of termite mounds, CRC Tropical Savannah Environmental Protection Agency. 2005. ASPANDIAR M.F. 2004. Mechanisms of metal transfer through sedimentary overburden. Extended Abstract in Minerals Exploration Seminar, AMECCRC LEME, 22-25 BLAKE D.H., PASSMORE V.L. & MULHING P.C. 1977. 1: 250 000 Geological Series Explanatory Notes - Billiluna Western Australia. Canberra, Department of Natural Resources Bureau of Mineral Resources, Geology and Geophysics:

Figure 6. Location and photo (inset) of the anomalous N. triodiae mound at Titania Prospect, NT.

CONCLUSION The observation of this mound within an aeolian regolith-landform unit can only be explained by what has been recorded for present-day termitaria and regolith-landform affiliations within the Tanami Desert, all N. triodiae mounds are found within alluvial landscape settings, and D. rubriceps within colluvial and aeolian settings, dominantly. The anomalously-located N. triodiae mound at Titania is therefore a relict landscape attribute, constructed when the palaeolandsurface was covered by alluvial sediments deposited by the nearby palaeochannel. Within two hundred years, the termitaria were surrounded by the shifting aeolian sands from nearby sand dunes, creating a sandy plain around the mound. The aeolian sands may not be conducive to the formation of new N. triodiae colonies nearby, cutting off the seasonal flooding which nourishes the grasses and shrubs required to sustain the colony, therefore isolating this mound from its contemporaries.

28.

BUREAU OF METEOROLOGY, 1984 - Climate of Australia, AGPS. DUNN C. 2007. Biogeochemistry in Mineral Exploration, Elsevier. GIBBONS L.M. & WEBB R.J. 1997. The discovery of the concealed Titania gold mineralisatiom, Granites-Tanami Region, Northern Territory. New Generation Gold Mines '97. Case Histories of Discovery, 9.1-9.15. GIBSON D.F. 1986. A Biological Summary of the Tanami Desert in the Northern Territory. Technical Report. Alice Springs, N.T., Conservation Commission of the Northern Territory. JOHNSON D.L., DOMIER J.E.J. & JOHNSON, D.N. 2005. Reflections on the Nature of Soil and Its Biomantle. Annals of the Association of American Geographers 95, 11-31.

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LEE K.E. & T.G. WOOD 1971. Physical and chemical effects on soils of some Australian termites, and their pedobiological significance. Pedobiologica 11, 376-409. LEE K.E. & WOOD T.G. 1971. Termites and Soils. London, Academic Press Inc (London) Ltd. LE ROUX J.P. & HAMBLETON-JONES B.B. 1991. The analysis of termite hills to locate uranium mineralization in the Karoo Basin of South Africa. Journal of Geochemical Exploration 41, 341-347. PETTS A.E. & HILL S.M. 2006a. Reading the Regolith: Mapping the Landscape and Developing an Understanding of the Contribution of Soil Biota to Regolith Formation in Northern Australia. Australian Earth Sciences Convention Conference Proceedings, Melbourne, Australia. PETTS A. E. & HILL S. M. 2006b. Nature's drillers and regional geochemical samplers: Termites and their implications for regolith geochemistry in Northern Australia. Australian Earth Sciences Convention Conference Proceedings, Melbourne, Australia. PETTS A.E. & HILL S.M. 2005. The 'ABC of Regolith: Attributes, Biota and their (Landscape) Context. International Geochemical Exploration Symposia Proceedings. Perth, Australia. REID N., HILL S.M. & LEWIS D.M. Spinifex biogeochemical expressions of buried gold mineralisation: the great phyto-exploration penetrator of transported regolith. Applied Geochemistry. In Press. ROQUIN C., FREYSSINET P., NOVIKOFF A. & TARDY Y. 1991. Geochemistry of termitaria and soils covering ferricrete: application to gold

exploration in Africa. Eurolat '91, Berlin, Germany, Technical University of Berlin. WATSON J.A.L. & ABBEY H.M. 1993. Atlas of Australian Termites. Canberra, CSIRO Division of Entomology. WILFORD J.R. 2000. Regolith- landform mapping and GIS synthesis for mineral exploration in the Tanami Region. Canberra, CRCLEME: 146R. WILLIAMS M.A.J. 1968. Termites and soil development near Brock's Creek, Northern Territory. Australian Journal of Science 31, 153154. WILLIAMS M.A.J. 1978. Termites, Soils and Landscape Equilibrium in the Northern Territory of Australia. In Landform Evolution in Australasia. J.L. Davies and M.A.J. Williams (Eds). Canberra and Conneticut, Australian National University Press: 128-141. WORRALL L., HILL S., KIRSTE D., PETTS A., PILLANS B. & REID N. 2005. Exploring through Cover in the Tanami: A Collaborative Regolith Research Project. Fieldwork Program Completion Report 4-14 October 2005. CRC LEME Restricted Report 225R. WORRALL L., JOSEPH J., KIM S., KIRSTE D., PETTS A., PILLANS B. & REID, N. (2006). Exploring through Cover in the Tanami: A Collaborative Regolith Research Project. Fieldwork Program Completion Report 15 - 25th August 2006. CRC LEME Restricted Report 248R. WYGRALAK A. 8. & MERNAGH T. P. 2001. Gold Mineralisation of the Tanami Region. Darwin, Northern Territory Geological Survey, 40.

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CHARACTERISATION OF REGOLITH PROFILES BY INFRARED SPECTROSCOPY S. Pontual AusSpec International, PO Box 205, Arrowtown, New Zealand sasha.pontual@ausspec.com

information. Infrared (both transmission and reflectance) analysis, on the other hand, is sensitive to localised within layer variations which cannot easily be detected by XRD and is therefore more sensitive to subtle variations in crystallinity than XRD (Crowley and Vergo, 1988). A further bonus specifically of using IR reflectance analysis is that sample preparation is far less time consuming than XRD, and often analysis can be carried out on site where it is most needed by the exploration geologist. The infrared spectra of kaolinites display vibrational features associated with the bending and stretching of the bonds in the hydroxyl ion (OH). The OH vibrations also combine with lattice vibrations to give features associated with OH and Al or Fe (Farmer, 1964). These vibrations produce features in the mid-infrared (MIR), which are termed the fundamental absorptions. The diagnostic absorption features of kaolinites in the short wavelength infrared (SWIR 1300-2500nm) are observed near 1400nm and 2200nm (Fig. 1). These features are harmonics of the MIR absorptions. The harmonic overtones of the OH absorptions around 2700nm in the MIR give the diagnostic absorption features observed between 1360nm and 1415nm in the SWIR (Fig. 1) (Crowley and Vergo, 1988). Combination harmonics of the OH vibrations with the AI-OH-AI vibration in the MIR produce the diagnostic "AlOH" absorptions near 2160-2200nm in the SWIR (Fig. 1). In addition, an absorption near 2235nm in the SWIR may be associated with a combination of an OH vibration with the Fe-OHFe vibration, the Fe-OH absorption.

INTRODUCTION Regolith profiles comprise assemblages of clays, iron oxides and silicates that are ideal for infrared (IR) spectroscopic analysis. This paper discusses the results of research and findings carried out 11 years ago (Merry and Pontual, 1996) and substantiated over the years with many application case studies. The study was initiated in response to a widespread issue in exploration: that is the need to routinely and consistently differentiate residual and transported profiles in drilling. The primary aim of the initial study was to investigate the potential for using changes in the infrared spectral signatures of kaolinite to discriminate between transported and residual material in the regolith. There are two reasons for this: 1) kaolinite is a common component of regolith material, and 2) there are clearly observed changes in the kaolinite spectral signature that relate to crystallinity variations. It was observed that transported and residual kaolinites appeared to be distinguished on their degree of crystallinity: typically residual kaolinites are highly crystalline, whereas transported kaolinites are commonly poorly crystalline. The presence of different smectite species in the lower saprolite horizon was also used to assess the primary lithology of the samples analysed.

KAOLINITE SPECTRAL CHARACTERISTICS XRD versus infrared Kaolinites typically display wide variations in crystallographic properties (Plancon and Tchoubar, 1977) as a result of varying modes of formation and/or subsequent transport or weathering (Keller, 1982; Muller and Galas, 1990). These include variations in crystallinity and the proportion of Fe^^ impurities, as well as other properties such as crystal size and shape. Typically, most crystallinity studies are carried out using XRD analysis. However, XRD analysis needs a certain degree of long-range ordering within the kaolinite to be able to detect the peaks that provide the crystallinity

Kaolinite crystallinity and SWIR spectra Study of numerous profiles supported the hypothesis that transported and residual kaolinites can potentially be distinguished on their degree of crystallinity: typically residual kaolinites are highly crystalline, whereas transported kaolinites are poorly crystalline. In the SWIR spectra of kaolinites, there is a high correlation between the Hinckley Crystallinity Index values calculated from XRD data, and the wavelength and intensity of the 2160nm absorption.

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Geological Society of Australia Abstract No. 87

Verypooriy

Kaoiinite

(Tystalline kaolinites

Kaolinite PoorlY crystalline kaolinites

1400 412

Moderatdy-highly crwtalline kao Unites

1300

1400

1500

1600

1 700

1800

1900

2000

Wavelength (nanometres)

2100

2200

2300

2400

Veryhighly

2500

crystalline kaolinite

Figure 1. Example of SWIR spectra of kaolinite and dickite.

Typically, this absorption becomes weaker and displays a shift from 2160nm to longer wavelengths with decreasing crystallinity (Fig. 2). Very poorly crystalline kaolinites typically display a weak absorption near 2180nm, similar to dickite (Fig. 3). This is because highly disordered kaolinite is crystallographically similar to highly disordered dickite (Brindley ef a/., 1986). On the basis of these results, kaolinites of different crystallinity can be classified into a number of spectral types, depending on the intensity of the 2160nm absorption, and the development of the 2180nm absorption. These types are summarised in Figure 3.

1300

1400

1500

1700

1800

1900 2000

2100 2200

2300

2400

2500

Figure 3. Changes in the kaolinite spectrum due to crystallinity variations.

i.e. three levels of poorly crystalline kaolinites, which cannot be identified or quantified by XRD analysis. Since the completion of the initial study, this classification of the kaolinite types has been routinely applied in the interpretation of many regolith sequences, with high success (Fig. 5).

INFORMATION IN THE SMECTITE CLAYS As well as providing information on kaolinite crystallinity, SWIR analysis also allows rapid determination of the smectite clay type, whether montmorillonite, nontronite or saponite. These clays typically form as a result of weathering of different lithologies. Nontronite is typically a product of weathering of mafic rocks, that were originally chlorite or amphibole rich. Saponite is typically a weathering product of ultramafic rocks, derived from weathering of talc and/or serpentine, and montmorillonite is typical of weathering of felsic rocks. Using the information

Figure 2. Correlation between the slope of the 2160nm kaolinite absorption vs Hinckley Index from XRD data.

Importantly, the kaolinite classification provided a method by which variations in kaolinite crystallinity have been assessed at all levels, in particular lower levels of crystallinity

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Geological Society of Australia Abstract No. 87

Figure 4. Characterising the regolith profile using the proportion of kaolinite together with the smectite species.

from the type of smectite clays observed in the lower saprolite and saprock, it is possible to assess what the likely primary rock type was.

References BRINDLEY G.W., KAO C.-C., HARRISON J.L., LIPSICAS M. & RAYTHATHA R. 1986. Relation between structural disorder and other characteristics of kaolinites and dickites. Clays and Clay Minerals 34 (3), 239-249. CROWLEY J.K. & VERGO N. 1988. Near-infrared reflectance spectra of mixtures of kaolin-group minerals: Use in clay mineral studies. Clays and Clay Minerals 36 (4) 310-316. KELLER W.D. 1982. Kaolin - A most diverse rock in genesis, texture, physical properties and use. Geological Society of America Buletin 93, 27-36. PONTUAL 8. & MERRY N.J. 1996. An exploration strategy to aid the differentiation of residual and transported kaolinites using field based spectral analysis. AusSpec Internal report SDP003. PLANQON A. & TCHOUBAR C. 1977. Determination of structural defects in phyllosilicates by x-ray powder diffraction - II. Nature and proportion of defects in natural kaolinites. Clays and Clay Minerals 25, 436-450. MULLER J.P. & GALAS G. 1990. Genetic significance of paramagnetic centres in kaolinites, in Kaolin 90 Symposium - Clay Minerals Society, (spec.pub.), Murray, Bundy and Casey (Eds.), 1-

CHARACTERISING THE REGOLITH PROFILE Using the kaolinite crystallinity information, together with the smectite information it is therefore possible to make a detailed evaluation of a regolith profile. The model illustrated in Figure 4 represents the kaolinite and smectite distribution through a typical complete residual regolith profile. Applying this model to the study of samples from a deeply weathered region allowed better understanding of the geochemical data from the project area, as shown in Figure 5.

CONCLUSIONS SWIR spectroscopy allows determination of the transported/residual contact, as well as assessment of whether a profile has been stripped or if it is complete. This information is vital for understanding the significance of geochemical data with respect to residual mineralisation signatures. As well as the example presented here, additional example case studies will be presented in the talk.

26.

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Geological Society of Australia Abstract No. 87

+ 1

IT^KM^

Cover

• •

Transported Cover Probable Transported Cover Possible Transported Cover

Basement Upper Saprolite

Figure 5. Example of an end-of-hole geochemical survey where a large proportion of the samples were found to be from either transported material or from the upper saprolite (dark greys or white). Lithology information was obtained from the associated smectites, where the lower saprolite and saprock were reached.

Lower Saprolite (Inf Volcanics) Lower Saprolite (Mafics) Lower Saprolite (Ultramafics)

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Geological Society of Australia Abstract No. 87

BIOGEOCHEMICAL PROSPECTING IN THE TANAMI DESERT N.Reid^ ^ S.M. Hill^ and D.M.Lewis^ ^ CRC LEME, School of Earth and Environmental Sciences, University of Adelaide, SA, Australia, 5005 ^ School of Chemical Engineering, University of Adelaide, SA, Australia, 5005

The Coyote Gold Deposit is located in Western Australia approximately 300 km southwest of Halls Creek and approximately 750 km northwest of Alice Springs. The mineralisation at Coyote is hosted by quartz veins in the turbiditic sediments of the Killi Killi Formation (1840 - 1830 Ma comprised of siltstones and sandstones). The Larranganni Prospects (Cuckoo, Hawk, Kookaburra, Osprey, Pelican, and Sandpiper) are roughly 40 km north of the Coyote Prospect. They have strong Au geochemistry associated with structurally complex zones in areas of shallow cover (Glengarry 2000). The gold is hosted within thin quartz veins within the underlying bedrock of the Stubbins Formation (1864 Ma metawacke, pelite and dolerite sequences). The Titania Prospect held by Newmont Asia Pacific includes 600,000 ounces of Au mineralisation, hosted in the Killi Killi Formation and intruded by dolerite sills (Wygralak and Mernagh 2001). The prospect is just south of the Rabbit Flat roadhouse. The eastern part of the prospect includes a palaeodrainage system and mineralisation mostly is covered by around 15 m of transported cover, that thickens to the east. The Hyperion Prospect held by Newmont Asia Pacific is approximately 70 km north of Rabbit Flat. Very little is known about the area except that it is a shallow gold prospect hosted within a dolerite sequence.

INTRODUCTION The Tanami Region hosts significant gold mineralisation, however most previous gold discoveries are associated with areas of exposed or shallow sub-cropping bedrock. Areas with significant transported regolith have been a major challenge for mineral exploration, and have had fewer exploration successes. Several plant species were investigated for use as a biogeochemical sampling medium over known Au mineralisation in the Tanami Region in northern Australia. Several of the species (Spinifex, snappy gum, desert paperbark, and two-nerved wattle) were growing over mineralisation covered by up to 15 m of transported regolith. The rooting depths of these species are considered to be the most significant factor affecting the dispersion halos produced in the target elements.

LOCATION Four known Au deposits (Coyote, Larranganni, Titania and Hyperion, Fig. 1) were sampled during 2005 and 2006 with the aim to 'rediscover' the mineralisation zones using biogeochemical techniques.

l-arranganni / Hyperion

METHODS Coyote

The Tanami Desert contains a variety of different plant species, some of which colonise vast parts of the region, such as spinifex {Triodia pungens), turpentine (Acacia lysiophloia), snappy gum (Eucalyptus brevifolia), bloodwood (Corymbia opaca), and dogwood (Acacia coriacea subsp. sericophylla). Each leaf sample was collected while wearing powder-free, latex gloves or in the case of spinifex, nitrile gloves. The gloves were changed between samples to prevent chemical build-up on the surface of the glove and contamination between samples.

j Titania

Tynyrni/rrcicK

Figure 1. Location of Tanami field sites.

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Plants in good health were chosen and immature plants and those growing in or near drill spoil were avoided. Samples were collected over the dry season as this has been shown previously to have generated the highest anomalism in other areas (Cruickshank and Pyke 1986; Stanton 1988; Brooks 1998; Hulme and Hill 2004). Leaves / phyllodes were chosen as the target plant organ because they have given the best results in previous studies (Hall et al. 1973; Davy and Ryall 1980; Lintern et al. 1997; Cohen et al. 1999; Hulme and Hill 2003). Samples were placed in brown paper bags, allowing the samples to breathe and reduce sample degradation, and were folded over at the top. Most spinifex samples were 'double bagged' to reduce the likelihood of the sample piercing the bag and gaining contaminants. Contamination risk during sampling was reduced by removing all watches, jewellery and other metallic objects. Hands were kept clear of sunscreen by washing and drying, and wearing a hat and sensible clothing rather than using sunscreen. Field sampling error was reduced by using the rigorous methodology adapted from (Hill 2002; Hulme and Hill 2003). The vegetation samples were then dried in a low temperature oven (45°C for 48 hours). The dried samples were ground to a fine powder using a rotating blade, stainless steel mill. Assays for the Coyote, Larranganni and Hyperion Prospects were done by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and Optical Emission Spectrometry (ICP-OES) through Genalysis Laboratories, Western Australia. Instrumental Neutron Activation (INAA) analysis for these samples was performed by Becquerel Laboratories, Canada. Assays for the Titania samples were done by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), at ACME Laboratories, Canada. The validity of the analytical procedures was calculated by laboratory duplicate samples taken from every 30*^ sample, of the full data set. The split of the sample was performed by grinding the entire sample to powder form, then shaking, rotating and agitating the sample to ensure homogeneity, then half the sample was placed into a new bag as a duplicate. Elemental concentration was plotted as a layer over the geo-rectified aerial photograph in ArcGIS 9.0 to show the location of assays with respect to the surface projection of known mineralisation extents and landscape features.

transported cover within a multi-element halo (As, Au, Ba, Br, Ce, La, S, Sc, Sm and Zn) where the different sizes of anomaly represent the different mobilities of each element (Reid et al. 2007, Fig. 2).

Figure 2. Coyote.

Spinifex

biogeochemical

signals

from

Other species such as the snappy gum (Eucalyptus brevifolia) was able to detect the mineralisation as a southerly dispersion pattern in the same elements. This was hampered by the geobotanical properties of this species which meant it did not grow directly over the mineralisation (Fig. 3).

RESULTS Coyote

Spiniex (Triodia pungens) was found to delineate the mineralisation zone through 5-15 m of

Figure 3. Snappy gum distribution across Coyote.

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Geological Society of Australia Abstract No. 87

Titania 322 leaf samples were collected from the Titania Prospect and were analysed for biogeochemical

signals. Of these, the spinifex (Triodia pungens), sandhill tea-tree (Melaleuca lasiandra), inland paperbark {Melaleuca glomerata), two-nerved wattle (Acacia bivenosa), and beefwood (Grevillea striata) were all able to detect the mineralisation zone, with varing degree of accuracy, using Au, As, REE's, Zn and S. The dispersion of these elements depended upon the species rooting depth (Fig. 4).

Figure 4. Spinifex, sandhill tea-tree, inland paperbark

and two-nerved wattle As results from Titania.

Hyperion The Hyperion Prospect was more of an unknown area, with little information available on the geology of the mineralisation. Detailed orthoimagery was not available so the results were plotted onto the regional TMI for the area. Snappy gum and spinifex were sampled over mineralisation and directly adjacent bedrock. From a multi-element suite, both species were able to differentiate between bedrock substrate and transported cover substrate. Using multiple elements, including Au and As these species and others (silver box, turpentine, and dogwood) showed chemical variation that corresponded with a change in magnetic intensity that may reflect the presence of the mineralisation zone.

Several plant species have been identified as potential biogeochemical sampling media in the Tanami region. They are each able to detect mineralisation using a multi-elemental suite where varying dispersion haloes for each element reflect their mobility and uptake potential by plants. The limiting factor for most of these species is their restricted distribution. All but the soft spinifex (Triodia pungens) have a significant landscape association that controls their distribution. Hence the soft spinifex is considered to be the most satisfactory sampling medium at prospect and tenement scale sampling regimes.

Larranganni Snappy gum growing on bedrock was sampled across the Larranganni prospects. The results showed that the mineralisation is reflected in a chemical response in the vegetation.

CONCLUSIONS

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Geological Society of Australia Abstract No. 87

ACKNOWLEDGEMENTS

HILL L.J. 2002. Branching out into biogeochemical surveys: A guide to vegetation sampling. In: Roach I.e. ed. Regolith and Landscapes of Eastern Australia 2002, 50-53. HULME K.A. & HILL S.M. 2003. River red gums as a biogeochemical sampling medium in mineral exploration and environmental chemistry programs in the Curnamona Craton and adjacent regions in NSW and SA. Advances in Regolith 2003, 205-210, CRC LEME, Perth. HULME K A & HILL S.M. 2004. Seasonal element variations of Eucalyptus camaldulensis biogeochemistry and implications for mineral exploration: An example from Teilta, Curnamona Province, Western NSW. Regolith 2004, 151155, CRC LEME, Perth. LINTERN M.J., BUTT C.R.M. & SCOTT K.M., 1997. Gold in Vegetation and Soil - Three case studies from the goldfields of southern Western Australia. Journal of Geochemical Exploration 58, 1-14. REID N., HILL S.M. & LEWIS D.M. 2007. Spinifex biogeochemical expressions of buried gold mineralisation: the great phyto-exploration penetrator of transported regolith. Applied Geochemistry In Press. STANTON N.L. 1988. The underground in grasslands. Annual Review of Ecological Systems 19, 573589. WYGRALAK A S . & MERNAGH T.P. 2001. Gold mineralisation in the Tanami region. Northern Territory Geological Survey Record 2001-011, Northern Territory Geological Survey.

We thank CRC LEME, Newmont Asia Pacific and Tanami Gold NL for funding and support, especially members of the Tanami Gold NL, Coyote exploration camp. Analyses were provided by Becquerel Laboratories, Canada, Genalysis Laboratories, Perth, and Acme Laboratories, Canada. Special thanks to assistance from members of the Tanami Group: Anna Petts, Dirk Kirste, Brad Pillans and Lisa Worrall. References BROOKS R.R., 1998. Plants that hyperaccumulate heavy metals. CAB International. COHEN D.R., SILVIA-SANTISTEBAN C.M., RUTHERFORD N.F., GARNETT D.L. & WALDRON H.M. 1999. Comparison of vegetation and stream sediment geochemical patterns in northeastern New South Wales. Journal of Geochemical Exploration 66, 469-489. CRUICKSHANK B.I. & PYKE J.G. 1986. Biogeochemistry and soil geochemistry of the Ranger One, Number 3 orebody, Australia. Uranium 3, 1-26. DAVY R. & RYALL W.R. 1980. Plants. Journal of Geochemical Exploration 12, 136-137. GLENGARRY 2000. Quartely Exploration Activity Report, Glengarry resources NL. HALL J.S., BOTH R.A. & SMITH F.A 1973. A Comparative study of rock, soil and plant chemistry in relation to nickel mineralization in the Pioneer Area, Western Australia. Proceedings of the Australasian Institute of Mining and Metallurgy 247, 11-22.

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RECENT DEVELOPMENTS IN REGOLITH RESEARCH WITH APPLICATION TO MINERAL EXPLORATION AND ENVIRONMENTAL MANAGEMENT S.L. Rogers Chief Executive Officer, CRC Landscape Environments & IVIineral Exploration, PO Box 1130 Bentley WA6102

on a uranium hydrogeochemistry exploration project in the Western Australian Wheatbelt following the Centre's discovery of groundwater uranium anomalies in the Upper Avon River Catchment. The application of high-energy X-ray techniques has led to significant advances in gold mineral host understanding. Nanoparticulate gold studies suggest rapid evaporation (days-months) is responsible for gold precipitation in sulfates. Hyperspectral analysis of surface illite has been identified as a mineralisation vector, and application of hyperspectral surveys to diamond exploration has aided the discovery of two new kimberlites at Pine Creek near Terowie, SA, employing spectral analysis of HyMap data. However, in addition to these more 'traditional' geoscience approaches, LEME has also invested significant effort into the relatively new fields of Exploration Geomicrobiology and Australian native plant Phytoexploration. The CRCs strategy to focus on biological mechanisms of trace element and mineral transport and transformation in regolith continues and has delivered significant outputs. A notable scientific highlight has been the publication of a paper by ANU PhD student Frank Reith and his co-workers in the prestigious international journal Science (Reith et al. 2006). The paper explained how a bacteria that precipitates gold in the regolith was isolated and identified. This study highlights the success of LEME in integrating traditionally unrelated fields of research. The discovery of the gold precipitating bacteria was made possible by applying molecular biology, genetic fingerprinting techniques that had originally been developed to study bacterial nutrient cycling biogeochemistry in agricultural soils. The development of phyto-exploration as an effective exploration-through-cover tool continues to deliver encouraging results. Whilst the use of plants to vector in on buried mineralisation is not a new concept, LEME has undertaken a systematic approach to developing this technology. By focussing on designing robust

INTRODUCTION The Cooperative Research Centre for Landscape Environments and Mineral Exploration (CRC LEME) was established in 2001 under the Australian Government Cooperative Research Centre Program to apply regolith science to the environmental and mineral exploration challenges facing Australia. The Centre was specifically created to develop and deliver scientifically robust, innovative, multi-disciplinary research partnerships to assist Australia's minerals exploration and natural resource management (NRM) sectors. This research, which has been delivered and designed with the end user in mind, was developed from the integration of traditionally disparate scientific disciplines and fields of research including geology, geophysics, geochemistry, soil science, microbiology, molecular biology, biochemistry, hydrogeochemistry, hydrology, plant biology and ecology. CRC LEME also places a strong emphasis on providing high-quality geosciencebased education to those entering the minerals or environmental management industries, and has one of the highest graduate industry employment uptakes of any CRC.

MINERAL EXPLORATION Mineral exploration focussed activities of CRC LEME have successfully applied regolith geoscience expertise (geochemistry, geophysics, geochronology, landscape evolution etc) to the vexed questions of identifying potential zones of mineralisation and determining mineral transport and transformation processes in landscapes dominated by cover. Key developments include; the application of hydrogeochemical techniques to vector in on buried mineralisation, work in the Tanami has applied this technique to successfully identify gold mineralisation through cover. In the northern Yilgarn, modelling of fundamental nickel sulfide deposit weathering has identified alternative hydrogeochemical reaction pathways for bedrock oxidation. Mindax Ltd and Quasar Resources Ltd have joined with LEME to embark

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Geological Society of Australia Abstract No. 87

DigHEM, Resolve, TEMPEST, and SkyTEM have been utilised. In addition, a new NanoTEM tool has been developed that can be towed behind a vehicle to create a shallower, but rapid means of data acquisition. Salinity research has also applied a new generation of groundwater flow system (GFS) products to groundwater and salinity management issues. These map and model-based products provide new insights into understanding groundwater and salt movements from small sub-catchment to regional scales. The CRC's Acid Drainage geochemistry research in Western Australia, in partnership with the WA Department of Water, Department of Agriculture and Food WA and the National Salinity Action Plan Engineering Evaluation Initiative, has led to a significant change in the 'risk assessment' procedures for salinity mitigation deep drainage engineering works. Drains intercepting 'naturally' acidic (pH<4.5), hyper-saline groundwaters in the WA wheatbelt have significantly elevated concentrations of trace metals (Cu, Zn, Pb), metalloids (As), and elements of the lanthanide and actinide groups. In these systems, managers have potentially replaced one environmental management issue (salinity) with another (trace element mobilisation and transport). To minimise the risk of geochemical impacts, it is critical to understand the mineralogy and geochemistry of the regolith and ground waters prior to drain construction, predict changes in geochemistry in response to drainage and identify processes occurring within the drains that influence geochemical changes. These environmental geochemical risk assessment outcomes have been achieved due to the application of exploration geoscience hydrogeochemistry techniques, again highlighting the success of LEME in integrating traditionally unrelated fields of research. In the last six years the widespread occurrence of inland acid sulphate soils (ASS), and the geochemical mechanisms underpinning their formation has been established by LEME. The CRC has put in place a framework within which integrated outcomes can be delivered that develop a national understanding of the spatial distribution and process of inland ASS formation and related hydrology in Australian regolith environments. Of particular significance is the advice LEME has provided about the environmental risks associated with the drying out of sulfidic materials in wetlands in the Murray Darling Basin. Based on four years of studies in the Loveday basin in SA, advice on geochemical changes and ASS formation has been provided to the management agencies responsible for planning the drought response in the SA Murray-Darling

sampling protocols, analytical QA/QC, identifying inter species and seasonal variations in plant organ trace element expression - and the differences in trace element expression in individual organs (phylodes, leaves, twigs, bark, litter) in addition to understanding the ecology and relationship of plants to the landscape, a more robust and practical technique has been developed for mineral explorers. Following on from the discovery in 2005 of an extension to the Pinnacles Pb/Zn lode near Broken Hill, partially the result of a River Red Gum leaf geochemical survey (Hulme et al. 2006), collaborative work in the Tanami with Anglo American, Newmont, Barrick and Tanami Gold has demonstrated the detection of anomalous gold concentrations in leaves of the common native grass Spinifex (Triodia pungens), and the observation that Spinifex roots can penetrate up to 30 metres down into the regolith. Recent results confirm that trace element patterns in Spinifex mirror those in adjacent groundwater. The quality and relevance of this work was reflected in a June 2007 feature article in New Scientist magazine, highlighting the Tanami project phyto-exploration and termitaria research of two of our LEME/UA PhD students Anna Petts and Nathan Reid. The uptake of uranium and thorium and concentration of these elements in leaves of a variety of native Australian plant species has also been recently demonstrated by LEME researchers in the Northern Flinders in collaboration with Heathgate Resources, indicating that phyto-exploration is a potentially viable method for uranium exploration through cover.

ENVIRONMENTAL MANAGEMENT The aim of the CRC's environmentally focussed R&D is to develop knowledge and techniques that facilitate the mapping, assessment and prediction of salinity stores and discharges, in both regolith materials and groundwater, and to assess and predict changes in landscape biogeochemical function in response to changes in hydrology due to management induced shifts in hydrological regimes, for instance installation of deep drainage, and formation of inland acid sulphate soils (ASS). A key development in the salinity mapping and assessment projects has been the successful application of geophysical techniques (airborne, in-stream, and ground based electromagnetics) traditionally used in the mineral exploration sector, combined with regolith core logging, hydrogeochemistry and landscape analysis to provide new insights into salinity hazard assessment and risk, salt storage and transport, and groundwater flow systems. A range of AEM platforms and systems, including

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Geological Society of Australia Abstract No. 87

undertake a National Geochemistry Survey of Australia (NGSA), is an outstanding endorsement of the team, led by Dr Patrice de DeCaritat, who developed this technique. The Survey will be funded under the Australian Government's new Onshore Energy Security Program and involve GA and State geoscience agencies.

Basin. In particular, a recent report on the generation of noxious odours from saline wetlands (LEME Open File Report 208) has been widely circulated among management agencies. The report featured as part of a brief on the environmental risks associated with the drying of saline wetlands presented to the SA Minister for the Murray.

5. Our Education and Training Program has again been outstanding in its achievements. LEME has now graduated 100 Honours students (against a KPI of 60), and is on course to graduate 60 postgraduate (MSc and PhD) students; the majority of whom are being 'snapped up' by the mineral exploration industry or government geoscience agencies.

IMPACT CRC LEME is able to demonstrate a number of key impacts its R&D has had on end users. In December 2005, the Allen Consulting Group in a report entitled, The Economic Impact of Cooperative Research Centres In Australia stated: 'Since the mid-1990s, technology developed by CRC LEME has contributed to the discovery of gold deposits with and inground value of more than $3 billion'.

FUTURE LEME Geomicrobiology and Phyto-exploration research are major components of the AM IRA P778 Predictive Geochemistry in Transported Overburden Project, which commenced in mid 2006. Industry partners include BHP Billiton, Independence Gold, Inco, Barrick Gold, Cameco, Teck Cominco, SGS Minerals and Newmont Australia. In addition to research activities in Australia, the project includes a regolith geochemistry component based in Chile with the University of Chile and industry partners Codeico, CVRD, and Rio Tinto. The project will continue beyond the cessation of the CRC in June 2008, through CSIRO Exploration and Mining. Acid drainage geochemistry projects will also continue beyond the cessation of the CRC. All LEME publications are digitally available as .PDF files free of charge from our web site: http://www.crcleme.org.au. CSIRO will maintain the LEME web-site for five years after cessation of operations in 2008. The CRC has entered into a collaborative agreement with AM IRA to transfer all relevant LEME technical reports and mineral prospect data into the AM IRA online database. Data Metallogenica, an international geoscience and prospect information repository. A series of six regional Exploration Under Cover Explorers Guides covering the Tanami, Gawler, Curnamona, Yilgarn, Thomson Orogen and Cobar provinces will be released over the next eight months. In addition field guides to Phyto-Exploration, and Hydrogeochemical exploration, an inland ASS Thematic Volume, and a Regolith Geoscience text book (published by CSIRO) will be released before the cessation of CRC activities in June 2008.

Other examples include: 1. Following the release of the Laterite Geochemical Atlas and Database for the Western Yilgarn Craton, a collaboration between LEME, CSIRO, Geological Survey of WA and the Minerals and Energy Research Institute of WA, a significant increase in exploration license applications (ELAs) in areas covered by the Atlas was recorded. More than 100 ELAs were lodged in the month following the release, compared to 40 in the previous month. 2. Release of the LEME/PIRSA Palaeodrainage and Tertiary Coastal Barriers Map of South Australia has led to a significant increase in ELAs over palaeodrainage systems in South Australia. Since May 2007, 78 ELAs have been lodged on ground over palaeochannels identified by the map. In July 2007, Diatreme Resources Ltd publicly acknowledged in a MiningNews.net article that its recent Gawler Craton tenement applications were the direct result of a review initiated by the palaeodrainage map. Both these products were released into the public domain at minimal charge to the end-user. They demonstrate that economic activity does result from the rapid, appropriate release of precompetitive geoscience information into the public arena. 3. The LEME/NSW DPI Thomson Orogen project is stimulating industry interest in this 'Green Fields' region, with ELAs in the region increasing from three, prior to project commencing, to 32 at the end of the second quarter. 4. The announcement made by GA in mid 2006 to adopt the Centre's regional geochemical survey methodology developed by the LEME Low Density Geochemical Survey Project, to

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international collaboration. In FITZPATRICK R.W. & SHAND P. (Eds) Proceedings of the CRC LEME Regolith Symposium, November 2006, 161-165. Published by CRC LEME, Perth.

References REITH F., ROGERS S.L., MCPHAIL D.C. & WEBB D. 2006. Biomineralisation of gold: biofilms on bacterioform gold. Science. 313: 233-236. HULME K.A., DUNN C.E. & HILL S.M. 2006. Biogeochemistry for mineral exploration in Canada & Australia: a comparison based on

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GAWLERCRATON REGOLITH BENCHMARKING: ORIGINS, TYPES, UTILITY AND WHERE M.J. Sheard CRC LEME, Geological Survey, Primary Industries and Resources SA, GPO Box 1671, Adelaide, South Australia 5001.

modification) has been applied to the more regional Atlas project outlined here. Each benchmark should provide a well-located representative reference column that has been fully described and examined by a number of regolith methods (materials logging, petrology, assay, PIMA, XRD, dating, etc.). A key feature of all benchmarks described by the new Atlas is that drilled samples and other specimens are readily available for visual or microscopic inspection, or for further analysis where warranted, through PIRSA's Glenside Drillcore Storage Facility.

BACKGROUND Transported regolith and deeply weathered basement, together conceal large tracts of prospective crystalline basement (cratonic and geosynclinal rocks) in South Australia, and that cover forms a major exploration impediment for much of the Gawler Craton. Interpreting and understanding that cover sequence has proven to be problematic for many geologists and explorers over the last several decades. To help overcome this impediment PIRSA Geological Survey in tandem with agencies from the CRC LEME i.e. CSIRO Exploration & Mining and Geoscience Australia, along with several Universities and exploration companies, have been involved in South Australian regolith research projects since late 1996. Those regolith studies have covered parts of the Gawler Craton, western Stuart Shelf, Adelaide Geosyncline and the Curnamona Province. Combined, those investigations now offer the possibility for a more regional appraisal, understanding and presentation of regolith for significant portions of these prospective terranes. This paper summarises the approach used for a comprehensive Regolith Benchmark Atlas covering the Gawler Craton (Sheard, in prep.). It is anticipated that similar Atlases for other significant areas of South Australia will be compiled in the near future.

Benchmark Types Three types of regolith exposure can form a Benchmark, those include: Type 1 - natural outcrop; Type 2 - drilled samples; and Type 3 human-made excavations (road and rail cuttings, tunnels, borrow pits, pipeline or cable trenches, quarries, costeans and mines, etc; Fig. 1). Profile complexity and/or depth limitations, can be partially overcome within a specific locality by compiling a composite profile from the variants or by utilising two of the three available Types (i.e. 1 + 2, or 1 + 3, or 2 + 3; see Table 1).

Benchmark Details Representative benchmarks are sited within well studied locations, and those studies have been summarised for the Atlas. Each selected profile has a tabulated summary of data, source papersreports, and profile photo(s) + log(s) + assay plots + the following, if available: petrology, PIMA mineralogy, XRD mineralogy and dating (Table 1). Accounts of the in situ weathered and transported regolith, as well as geochemistry and suitable sample media, are provided for each benchmark. Most locations have 2 benchmarks but a few cases have 3 or 4.

BENCHMARKING In geology a Type Section is really just another name for a Geological Benchmark. However, regolith profiles commonly involve weathering zones that variably transgress geological boundaries. Therefore the term "type section" has been avoided for the new Atlas in preference for regolith benchmark. A methodology for the Atlas is drawn from examples used in pedology and geomechanics where data are presented from drillholes and/or excavations to form key reference columns or benchmarks. Those methods were successfully demonstrated by Sheard and Bowman (1996) for the Adelaide metropolitan soils, stratigraphy and engineering geology study. Their systematic approach (with

Benchmark Utility Benchmarks can augment new in-field studies within a relevant location or tenement area; or can assist with more thorough evaluation of proposed investigations from an office-laboratory context. They also provide a training opportunity for geological staff unfamiliar with regolith, its terminology and/or its appropriate sampling for assay. Such training may involve accessing samples at PIRSA's Drillcore Storage Facility, or

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in-the-field using local samples and/or exposures plus the nearest benchmarks sites.

BENCHMARK LOCATIONS Benchmarks in the new Atlas of Sheard (in prep.) are grouped within a province domain or a defined region, allowing ready comparisons. Volume 1 includes Benchmarks 1-20 covering: the Harris Domain (greenstones and related

rocks), the Central Gawler Gold Province (granite terranes), and the Eyre and Yorke Peninsulas (felsic terranes; Fig. 2). Included mines are from Earea Dam Gold Field and Moonta (Poona and Wheal Hughes Cu-Au Mines). Volume 2 includes Benchmarks 21-33 covering: part of the Christie Domain - including the Challenger Gold Mine (Fig. 2).

136 m

Type 1: Natural outcrop: intensely weathered and silcreted Glenloth Granite, western shores of Lake Harris, Harris Domain. Protolith and saprock are not exposed. Hammer (centre) is 0.3 m long.

Type 2: Drilled profile (core), weathered Kenella Paragneiss, Earea Dam Goldfield, Harris Domain. Drillcore penetrates to 13.5 m, protolith is cut at 12.8 m. There is some core loss from this profile.

Type 2: Drilled profile (cuttings in chiptray): weathered Hopeful Hill Basalt (komatiitic), Harris Greenstone Belt, Harris Domain. Protolith is cut at -34 m.

Type 3: Excavated profile (mine pit), m transported regolith on m of weathered Moonta Porphyry exposed at Poona Cu-Au Mine, Moonta, southern Gawler Craton. View --WSW, protolith is 1-12 m below surface.

Figure 1: Examples of the three regolith benchmark types used in the Regolith Benchmark Atlas of Sheard (in prep.).

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Table 1: An example data tabulation summary for Benchmark 22 from Sheard (in prep.). This is one of three regolith benchmarks covering the Challenger Gold Deposit. Benchmark 22 is composite, involving two drillholes and a regolith pit profile. Table XX: Benchmark 22 reference data; composite of drillholes 95GHAR115 & GG121 (Type 2, drill cuttings profiles) + regolith pit GCP121 (Type 3, excavation). Items Regional location map Local-site location map GPS coordinates, attitude & elevation.

Site access, owner

Related drillholes Drill / Pit sample photos + logs Sample types Sample storage Lithotypes Petrology

Geochemistry XRD mineralogy PIMA spectral data

Dating

Target elements Potential Pathfinder Elements Useful sampling media Key reference sources

Figures, Data, Sources Figures 110-112. Figure 113. • RAB drillhole 95CHAR115: Zone 53, 363622 E, 6693740 N, GDA 94. Vertical. AHD: -208 m (estimated from map data). • RC drillhole GC121: Zone 53, 363619 E, 6693752 N, GDA 94. Vertical. AHD: -208 m (estimated from map data). • Regolith pit GCP121: Zone 53, 363619 E, 6693752 N, GDA 94 About 1 km N of the track between Commonwealth Hill and Mobella Pastoral Station Homesteads, on E end of Mobella Pastoral Lease. Site Lease holders: Mobella Pastoral Station & Dominion Mining NL. Part of the Gawler Joint Venture exploration multiple drillhole grid. Yes: Figures 128, 129, Plates 17-23 and Tables 53, 54. Drill chips: chiptrays + kg bags for RC drillhole GC121, + -1-2 kg bags and numerous 0.5->5 kg blocks for Regolith Pit GCP121. PIRSA Drillcore Storage Facility, 23 Conyngham St, Glenside. Weathered Christie Gneiss. Yes: for regolith pit samples. Plates 22, 23. See also Challenger Regolith section above Figure 118.; and Mason and Mason (1998). Yes: Figures 123-125,130,131 and Table 49. No. Not for this drillhole but many others have data available (van der Wielen, 1999). Analytical Spectral Detection (ASD, an advanced PIMA) was carried out on all available drilled samples within --3 km radius of the Challenger Mine in 2003; however, that data remains restricted access (Gray & Lintern, 2004; Lintern, 2004b; Figure 125). Yes, for Christie Gneiss protolith, U-Pb zircon age of -2440 Ma (Fanning, 2002), and peak metamorphic age of -1710 Ma (Tomkins and Mavrogenes, 2002). Au Complex & sample media dependent, refer to Table 49. Calcrete, soil, vegetation, silcrete. Lintern and Sheard (1999a, b); Lintern and Sheard (1998); Povey (1999); van der Wielen (1999); Poustie etal. (2002); Lintern (2004b); Poustie (2006); Edgecombe (1997); Mason and Mason (1998).

References SHEARD, MJ. (in prep.). Regolith Benchmark Atlas, Gawler Province, South Australia. To be co-released as: CRC for Landscape Environment and Mineral Exploration. Open File Report / Primary Industries & Resources, South Australia. Report Book.

SHEARD, M.J. & BOWMAN, G.M. 1996. Soils stratigraphy and engineering geology of near surface materials of the Adelaide Plains. Primary Industries & Resources, South Australia. Report Book, 1994/09.

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