Mesozoic rocks are known from most of the major islands of Svalbard, namely, Spitsbergen, Nordaustlandet, Barentsoya, Edgeoya, Kong Karls Land, Hopen, and Bjornoya.
Sedimentary rocks range in age from Triassic (early Scythian) through Early Cretaceous (Albian) and comprise three lithostratigraphic units: Sassendalen Group (Gries-bachian to Anisian), Kapp Toscana Formation (Ladinian to Toarcian), and Adventdalen Group (Bathonian to middle Albian). The facies are mostly drab shale, siltstone, and sandstone (generally marine shales and continental sandstones), which contrast markedly with the underlying Permian cherty carbonate rocks, and not so obviously with the resistant overlying Tertiary coal measures. The marine strata are characterized by the presence of ammonites, bivalves, and saurions; the continental strata contain plant beds and thin coal seams, some bivalves, and vertebrates. The succession and the facies are very similar to those of Arctic Canada. The most conspicuous rocks in the older part of the sequence are the cliff-forming mafic igneous sills and flows of latest Jurassic and/or Early Cretaceous age.
The Mesozoic tectonic activity followed a relatively stable late Paleozoic history, producing a marked change of facies but conformable strata. The maximum known thickness of Mesozoic strata is about 3 km (10,000 ft). The first distinguishable disturbance (warping and faulting) accompanied basic igneous activity but caused little change in sedimentary facies. The principal unconformity represents a hiatus which lasted from late Albian to early Paleocene(?) time. There is local overstep of Tertiary rocks onto the lowermost Triassic, but generally only the uppermost Albian members are missing. These minor disturbances may be related to (1) movements that culminated in the West Spitsbergen orogeny in early to mid-Tertiary time and (2) the mainly Tertiary Arctic Ocean spreading. Svalbard probably was moved from subtropical to tem-perate latitudes in Mesozoic time, and Arctic latitudes were not reached until later.
Petroleum propects in the Arctic are enhanced by the presence of Mesozoic rocks which provide source and reservoir rocks and caprocks.
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Following the discovery of Prudhoe Bay oil field in 1968, much attention was turned to the Arctic in the search for giant hydrocarbon accumulations. The Soviets had already proved giant reserves in their West Siberian Basin, and exploration was moving ahead quickly in the Canadian Arctic. Plans were drawn up for an AAPG Symposium on Arctic Geology and held in February 1971. Papers were selected from the Symposium for this publication and cover seven topical groupings: Regional Arctic Geology of Canada, Regional Arctic Geology of the Nordic Countries, Regional Arctic Geology of the USSR, Regional Arctic Geology of Alaska, Comparisons in the North Atlantic Borders, Evolution of the Arctic Ocean Basin, and Economics of Petroleum Exploration and Production in the Arctic.