Rift, Inversion and Thrust Structures in the Russian Chukchi Sea

Bulat Ikhsanov

The remaining low exploration degree of the Russian East Arctic offshore region by seismic methods, as well as the lack of wells allow only predictive conclusions on the rock formation history. The Chukchi Sea region is not an exception from these areas. Total extent of seismic lines in the Russian part of the Chukchi Sea reaches about 16,500 line km, including 13,000 taken for analysis described in this paper. The key regional structures are the South Chukchi and North Chukchi sedimentary basins, and separating them the Wrangel-Herald fold-thrust belt. Stratification of regional unconformities in the sedimentary cover of studied basins was defined by analogy to the conjunctive American offshore and onshore parts. The North-Chukchi and South-Chukchi basins are rift basins. Their origination and the subsequent submersion occurred, approximately, in the Aptian-Late Cretaceous stages. Approximately on the Cretaceous - Paleocene border a formation of the Wrangel-Herald fold-thrust belt took place. Synchronously with this event inversion deformations happened in the southern part of the North Chukchi basin. Transpression deformations on the Cretaceous - Paleocene border took place also in the South-Chukchi basin. In the Cenozoic time near the North-Chukchi basin the large clinoform progradation system was formed with northwards material transportation. The North-Chukchi basin became a part of the Arctic Ocean passive margin. In the South-Chukchi basin in the Cenozoic time the transpression deformations took place and inversion structures were formed. Young Late Cenozoic faults are typical for the North-Chukchi basin. Under the rift complex in the North Chukchi basin it is possible to identify almost not deformed the Late Paleozoic – Lower Cretaceous sediments. Under the rift complex in the South-Chukchi basin in places one can identify the deformed sedimentary sequences. The folding processes continued until the Aptian time. The hydrocarbon systems were reviewed for the Chukchi Sea sedimentary basins.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013