Wave-rippled bedding surface in Eocene sandstone deposits in the Central Basin on Spitsbergen. Photo: Jan Stenløkk
M
ajor rifting with continental break-
evidence remaining to help establish models
tances, indicating that the entire Sørvestsnaget
up commenced in the Late Creta-
for the Eocene paleogeography of the Barents
Basin was the site of deposition of sandy grav-
ceous along the North Atlantic rift
Sea platform and the Kara Sea.
ity flows.
and in the Amundsen Basin to the north. As a
Due to the above-mentioned decoupling of
Palaeocene and Lower Eocene marine mud-
result of this rifting, a dextral stress field was
the Barents Shelf from the areas on the other
stones are present in the Hammerfest Basin and
set up along the Senja-Hornsund lineament,
side of the de Geer Zone, the major eastern
western parts of the Nordkapp Basin, resting
and during the Palaeogene, this mega-fracture
and northern parts of the shelf were uplifted,
unconformably on the Cretaceous succession
acted as a relay zone between the spreading
but the basins of the westernmost Barents
with a marked hiatus. However, the Cenozoic
centres. The compressional component of the
Shelf continued to subside and received sig-
is entirely absent below the base of the Quater-
movements along the Hornsund Fault Zone,
nificant amounts of sediment. The Harstad Ba-
nary in surrounding platform areas such as the
between the Svalbard region and North Green-
sin, Tromsø Basin, Sørvestsnaget Basin, Vest-
Finnmark and Bjarmeland platforms and parts
land, is manifested by the Fold- and Thust-Belt
bakken Volcanic Province and the areas west
of the Loppa High, as well as in the northern
on Svalbard. Sea-floor spreading began in the
of the Knølegga and Hornsund Fault Zones,
parts of the Barents Sea.
Norwegian-Greenland Sea south of the Green-
were principal areas of clastic deposition. Large
On Svalbard, western Spitsbergen was the
land-Senja Fracture Zone in the Early Eocene.
volumes of sediment derived from the newly
site of the Spitsbergen Orogeny. The orogeny
Significant reorganisation of the spreading pat-
uplifted areas of the shelf were deposited here
itself took place in the Palaeocene, but it set the
terns occurred in the Mid Eocene, and spread-
during Eocene times.
scene for the subsequent Eocene deposition in
ing expanded farther north to the southern limit of the Hornsund Fault Zone.
122
Fossil cone preserved in Eocene sandstone, Svalbard. Photo: Jan Stenløkk
Whilst the Palaeocene record is entirely
the foreland basin of the mountain range, com-
made up of grey to olive-coloured claystones,
monly referred to as the Spitsbergen Central
Little is known about Eocene palaeogeogra-
the Eocene succession reflects episodes of con-
Basin. During the Eocene, the Central Basin
phy in the Pechora and Kara seas and eastern
siderably more active clastic deposition. Basi-
was a marine embayment apparently linking
parts of the Barents Sea. These areas probably
nal blocky sandstones of gravity flow origin are
up with the oceanic conditions in the western
constituted a tectonically stable epicontinen-
encountered in drillcores in the central parts of
Tertiary basins. As in the Sørvestsnaget Basin
tal mega-region, and were either uplifted con-
the Sørvestsnaget Basin. Furthermore, Eocene
in the south, the Eocene was also the major
tinental hinterlands or shallow-marine seas
gas-bearing sandstones have been recorded on
epoch of active deposition in the Spitsbergen
with very limited net deposition. Sediments
the northwestern margin of the Sørvestsnaget
Central Basin where siliciclastics sediments
that may have been deposited, were subse-
Basin, probably deposited in upper slope to out-
prograded in from the orogenically elevated
quently removed due to later Neogene uplift
er-shelf settings. The seismic signature of the
western margin.
and erosion. Consequently, there is very little
sandstones can be extrapolated over large dis-
Eocene