South Chukchi Sedimentary Basin’S Structure Features

Nikolay A. Malyshev, V. V. Obmetko, A. A. Borodulin, E. M. Barinova, and B. I. Ikhsanov
Rosneft, Moscow, Russia.

South Chukchi sedimentary basin is located in the back part of Vrangel-Gerald thrust- fold zone on the north-west extension of Kotsebu and Hope basins, which are located in American sector of Chukchi Sea. There are three basic stages in its development. During the initial stage (Albian-Late Cretaceous) rift zones were formed, associated, apparently, with collapse of Chukchi-Brukian orogen. In the Palaeogene-Miocene period in the region the stretching regime had been remained proceeding till Late Oligocene-Early Miocene with an essential strike slip component. At the same time similar processes took place on whole East Arctic area. Wide development of transtensive structures within Laptev Sea, East-Siberian and Chukchi sea shelves, and also onshore took place. It is obvious that these events are associated with development of the Eurasian basin and, apparently, with the plate-tectonic reorganization phase during the general geodynamic evolution of the Arctic region. There was rather quiet subsiding of region during final Pliocene-Quaternary stage of the basin development.

These events have played a major role in sedimentary cover forming. On the seismic sections they are traced as two unconformities which divide the basin into three structural complexes:
- Lower rift (K2), consists of grabens and semi-grabens and highs dividing them;
- Middle post-rift (Pg-N1), with extended northwest trend transtension structures;
- Upper syneclise (N2-Q), with subhorizontally laying rocks.

In the central part of the South Chukchi basin along the main strike slip zone, that divides basin into two large troughs - Schmidt and Sredinnyi, on its bend site the anticline zone with «pop-up» structures was generated. At removal from this strike slip zone the amplitude and the sizes of positive structures decrease. Strike slips have occurred on reactivated faults of the lower structural complex and the basement. But in some cases they are new, have other sub latitudinal orientation and split earlier faults.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia