Franz Josef

Bitumens of Franz Josef Land

Internet Geology News Letter No. 7, August 23, 1999

Bitumens were found at numerous places in Franz Josef Land (Russia) in 1993-95. On Khays Island in the central part of the archipelago the exposed sedimentary section consists of sub-horizontal sand-silt deposits, which are invaded by dolerite-basalt dikes. Width of these dikes is 25-150 m. Dolerite-basalt sills are also present. Close to the dikes the sandstones are almost everywhere impregnated with bitumen, suggesting the presence of oil pools at depth (Petroleum Geology, vol. 31, no. 4, p. 365-367, 1997).

On Wilczek Land Island Triassic-Jurassic sedimentary rocks occur in a north-northeast-trending anticline, along the axis of which is a series of sub-parallel dolerite dikes. These dikes are brecciated and cut by numerous hydrothermal veins. Liquid bitumen is present in the breccia zones and in the veins. When the rock is crushed, the bitumen bleeds out and solidified quickly. Also present are "froth" veins, indicating that as these veins formed they were saturated with hydrocarbon gases. Such phenomena also suggest the presence of oil-gas pools at depth (Petroleum Geology, vol. 33, no. 1, p. 104-106, 1999).

Numerous occurrences of bitumen have been recorded on Graham Bell Island. The section here consists of Upper Triassic and Middle and Upper Jurassic clastic rocks. Basalt and dolerite dikes have been emplaced along faults, and bitumens occur in the dikes. The bitumens associated with the dikes on Graham Bell Island as well as on all the islands of Franz Josef Land are interpreted as having been introduced along with hydrothermal activity.

Unexpected was the finding of pieces of black bituminous shale in glacial deposits on Graham Bell Island. This material is similar to the Cambrian Kounam Shale of East Siberia and Jurassic Bazhenov of West Siberia. It contains 41.5 percent organic carbon (Petroleum Geology, vol. 31, no. 4, p. 368-371, 1997). Although this rocks was not found in place, it indicates that outstandong source beds are present somewhere. This is a vast unknown region, and these pieces of bituminous shale in glacial deposits may indicate a prize that we now see but dimly.