The Structure of the South and North Chukchi Sedimentary Basins and the Wrangel Arch from the Basis of Newly Acquired Seismic Data (Chukchi Sea, Russian Arctic)

Vladimir E. Verzhbitsky¹, Erling Frantzen², Kjell E. Trommestad², Tatyana Savostina¹, Alice Little³, Sergey D. Sokolov⁴, Marianna I. Tuchkova⁴, Tom Travis⁵, Oksana Martyntsiva⁵, and Magnar Ullnaess^2
1TGS-NOPEC Geophysical Company Moscow, Moscow, Russian Federation
²TGS-NOPEC Geophysical Company ASA, Asker, Norway
³TGS Geological Products and Services, Stavanger, Norway
⁴Geological Institute, Russian Academy of Sciences, Moscow, Russian Federation
⁵TGS-NOPEC Geophysical Company (UK) Limited, Bedford, United Kingdom

During the summer of 2006 TGS-NOPEC conjointly with “Geophysical Solutions Integrator” acquired new seismic data in the Russian part of the Chukchi Sea. The area of the Chukchi Sea studied includes (from S to N): South Chukchi sedimentary basin (1), Wrangel Late Kimmerian Arch (2), North Chukchi sedimentary basin (3). Due to the absence of offshore wells in the Russian sector of Chukchi Sea, the interpretation of acquired seismic data and definition of probable hydrocarbon potential must be based on the comparison with the US sector of the Chukchi Sea and the Alaska North Slope, as well as on the geology of Northern Chukotka and Wrangel Island. In the northern part of the Wrangel Arch most of the thrust faults are N-vergent, but double-vergent transpressional structures also occur. To the North of the Wrangel Arch, a clearly recognizable angular unconformity in the upper parts of the North Chukchi basin may correspond to the Lower/Upper Brookian (~Cretaceous/Tertiary) boundary, although it may be as old as Early Cretaceous (pre-Aptian) in age. The maximum Pz-Mz-Cz sediment thickness of the North Chukchi basin exceeds 16 km. In the South Chukchi basin the thickness of sediments (Late Cretaceous?-Cenozoic) mostly doesn’t exceed 3-4 km, but in some places reaches 5-6 km. The geometry of the faults indicates an extensional/transtensional setting of the South Chukchi rift basin development. The changes in phase or polarity in upper parts of the sedimentary cover, listric fault planes in the pre-rift sequences, associated with areas of reduced reflectivity in the upper sediments may point to a gas presence. The syn-orogenic (pre-rift) Upper Jurassic-Lower Cretaceous organic-rich terrigenous sequence (containing visible plant remnants), which is exposed onshore in Northern Central Chukotka and is probably present in the Chukchi Sea, may represent regional gas source rocks.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas