Major siliciclastic provenance was from southern and eastern areas, with lesser sediment contributions from northern and northeastern directions. Southeastward marine transgressions occurred, but eastern Barents organic matter is still considerably more humic than in other Arctic regions such as northern Alaska and the Canadian Sverdrup Basin. Similar depositional and tectonic conditions actually existed from Late Permian through Early Jurassic time, but best eastern Barents source rocks are probably Early and Middle Triassic in age (fig. 4).

Eastern Barents Triassic source rocks are medium to dark shales, locally coaly, that contain type II (oil-prone) to type IV (as per Ferriday and others, 1995; gas-prone) kerogen (fig. 3, limited subsurface data). This total petroleum system is probably gas dominated because of the abundance of gas-prone kerogen, the rapid burial, and the relatively advanced stage of thermal maturity for large areas of Lower Triassic rocks in the basins (fig. 2a). Gross shale thickness ranges from hundreds to thousands of meters. Subsurface total organic carbon (TOC) content is variable to 20 wt% (2-8 wt% typical), and hydrogen index (HI) ranges from 200-500 mg/g TOC (Leith and others, 1993; Ferriday and others, 1995). 

Other Source Rocks – Jurassic and Possible Devonian
A Late Jurassic warm and humid climate coincided with a sea level maximum and localized conditions of restricted bottom-water circulation in the Arctic region (Leith and others, 1993). Dark gray to black, bituminous marine shales tens of meters thick were deposited in several-hundred-meter water depths, but these source rocks are largely thermally immature in the eastern Barents basins (Oknova, 1993). They are the Bazhenov and Hekkingen stratigraphic equivalents of adjacent regions in Russia and Norway, respectively, where they do reach thermal maturity.

Arctic Upper Jurassic source rocks are thicker but lower in TOC away from the eastern Barents basins. In the North American Arctic, thicknesses range from hundreds to 1000 m, and TOCs range from 1-9 wt%. In contrast, central and southern Barents subsurface TOCs can reach 15-25 wt%, but with thicknesses of just 20-30 m (Leith and others, 1993). Norwegian Barents Sea thicknesses approach 100 m. Kerogen types are generally more oil-prone upward and range from type III to amorphous type II. An early-oil stage of thermal maturity possibly is reached at Upper Jurassic level in the deepest basin areas (fig. 2a, fig. 2b, and fig. 3).

The presence of Devonian Domanik-equivalent, oil-prone, shaly basinal carbonate source rocks is unproven much north of the coastline in the Timan-Pechora Basin Province (see Lindquist, 1999, and cited references therein) and such facies are missing on Kolguyev island. If present in the Barents basins, Devonian source rocks would be overmature except for the eastern basin flanks along the Novaya Zemlya archipelago. Devonian source rock facies are known to exist in the North Kara depression on the east side of the Novaya Zemlya archipelago (Borisov and others, 1995).