Russian Chukchi Sea Shelf: Structural Style, Sedimentary Basins Stratigraphy and Hydrocarbon Potential
Vladimir Verzhbitsky1, Sergey Sokolov2, Marianna Tuchkova2, Leopold Lobkovsky3, Svetlana V. Malysheva1, Sergey Katkov2, and Mikhail Kononov3
1LLC «Gazpromneft NTC», Saint-Petersburg, Russian Federation.
2Geological Institute RAS, Moscow, Russian Federation.
3Shirshov Institute of Oceanology RAS, Moscow, Russian Federation.
Russian Chukchi Sea shelf belongs to the vast area of the remote and poorly explored East Arctic region. The studying area attracts the broad interest mainly due to the existence of the sedimentary basins of the similar structural position and origin with those of Arctic Alaska, which is very well-known as the famous oil and gas bearing province. South Chukchi (Hope) Basin is filled by Cretaceous-Tertiary sequences, whereas North Chukchi Basin could contain the strata of Paleozoic age (Silurian? Devonian-Carboniferous?) at its base. The region of our investigations also represents one of the key areas for understanding the Phanerozoic tectonic evolution of Circum-Arctic, including the origin and development of Amerasian Basin of the Arctic Ocean. We interpret the shelf structure and stratigraphy using main geological events known for the Chukotka and Wrangel Arch Fold Belts, also taking into consideration the information on Brooks Range and North Slope of Alaska. Our research is mostly based on the broad compilation of available onshore geological data (including some of the field-work results) on Chukotka Peninsula and Wrangel Island and published offshore seismic data. For the most promising in terms of hydrocarbon discoveries the North Chukchi Basin we delineated four main angular unconformities: pre-Aptian (Lower Cretaceous, LCU, ~ 125 Ma), intra-Albian (IAU, ~ 106 Ma), Cretaceous-Tertiary (Mid-Brookian, MBU, ~K/Cz) and Late Oligocene (Mid-Miocene?), sub-dividing five main seismic complexes. The main defined boundaries could correspond to Late Mesozoic Chukotkan orogeny completion in the end of Neocomian (1), beginning of formation of voluminous Okhotsk-Chukotka Volcanic Belt in Albian (2), regional uplift, erosion and post-collisional compression events (3 and 4) correspondingly. For the South Chukchi Basin we strongly support Aptian time of the sedimentation onset, which was pre-dated by syn-orogenic intermontane depression development in Late Jurassic-Neocomian. Similarities in geological history and depositional settings of Russian and US sectors during Late Paleozoic-Cenozoic, wide-spread thrust fault and anticline structures in Pz-Cz sedimentary units, wedge-outs, angular and stratigraphic unconformities, “gas chimneys” on seismic records, buried progradational units and anomalous concentrations of hydrocarbon gases in the bottom sediments may point to significant prospectivity of Russian Chukchi Sea shelf. We relate the widely occurred in the entire Chukchi Sea Region E-W to NW-SE striking Aptian-Cenozoic dextral strike-slip faults to the opening of deep-water Makarov Basin in Aptian-Albian-Late Cretaceous(?) and Eurasian (Cenozoic) Basin of Arctic Ocean.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.�����������������������������������������������������������������������