Marine shelves of Russia cover some 4,500,000 sq km, and approximately 2,000,000 sq km of the Arctic Ocean are favorable for oil and gas. Assessed resources of this Arctic Shelf have been placed at 100 billion tons oil equivalent (700 BBOE). Resting on basement in Barents-Kara region is a sedimentary section, in the lower part of which are probably Silurian-Carboniferous rocks 3-4 km thick. Overlying are Permian-Triassic clastics 10-11 km thick. Next are Jurassic-Cretaceous clastics up to 4 km thick. At the beginning of the Jurassic fresh-water sands and clays collected; then marine sediments, largely clays, were deposited in Middle and Late Jurassic time and have been the main source beds for hydrocarbons. The gas-condensate pools of giant Shtokmanov field are in Middle and Upper Jurassic sandstones. Two large depressions are present in the Russian sector of the Barents Sea: North Barents and South Barents. They are separated by the Ludlov saddle, which measures 200 by 300 km and has an amplitude of 500 m. Both of these depressions and the saddle are combined into the East Barents mega-downwarp, which is a single oil-gas basin with large kitchens and zones of oil-gas accumulation. Seismic surveys to the north of Ludlov saddle have disclosed a large high that measures 100 by 100 km. Gas resources on this Lunin high are expected to be not less than 105 tcf. Then the Admiralty high, located to the west of Novaya Zemlya, is expected to yield large discoveries in the first half of the Twenty-First Century. Only three deep wells have been drilled in the South Kara depression. They discovered Rusanov and Leningrad gas-condenstae fields, which contain more than 10 pay zones with resources assessed at 280 tcf. The North Kara depression has enormous potential but has received little study. Assessment must wait far beyond the year 2010. Four basins are present in the eastern sector of the Russian offshore Arctic: Laptev Sea, East Siberian Sea, North Chukchi, and South Chukchi. Rifting has controlled the geology of the Laptiv Sea region. Several raised blocks are present, and they are highly favorable for hydrocarbons, particularly gas. To the northeast of the New Siberian Islands are folded Mesozoids, which are called the DeLong Terrane. Thickness of the Jurassic-Cretaceous section there is 3-4 km. Very little information is available on the East Siberian Sea oil-gas basin. The geology of the New Siberian Islands probably extends there. The section of the North Chukcki basin may be similar to that of the North Slope of Alaska because they occupy similar tectonic positions. However, they do not appear to be continuations of one another. Six seismic complexes are recognized in the North Chukchi basin. Some of these appear to correlate with Alaskan geology. They range in age from Permo-Triassic to Recent, and total thickness exceeds 10 km. Favorability for oil and gas is high. The South Chukchi basin is on a Mesozoic base. An analog is the Hope basin of Alaska. Thickness of the sedimentary section is up to 4 km, and the basin is gas-prone. (Taken from Nikitin and others, 1999; digested in Petroleum Geology, vol. 34, no. 3, p. 226-233, one map and two cross sections). Copyright 2000 James Clarke. You are encouraged to print out this News Letter and to forward it to others. Earlier News Letters can be downloaded at our website http://geocities.com/internetgeology/ Inquiries concerning Petroleum Geology may be made by telephone at (703) 759-4487.