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Peter W. Baillie1, Vladimir Kudelkin2, Paul A. Gilleran1
(1) TGS-NOPEC Geophysical Company, West Perth, Australia
(2) Dalmorneftegeofizika Trust, Yuzhno-Sakhalinsk, Russia

Abstract: Geological development and prospectivity of the Sea of Okhotsk, Far Eat Russia

The Sea of Okhotsk, containing more than 20 discrete depocentres (“basins”), is bounded by the Russian mainland, the Kamchatka-Kuril island arc and northeast Hokkaido (Japan).

The area lies over a triple junction where the continental Eurasian and North American Plates meet the oceanic Pacific Plate. Subduction of oceanic crust at an evolving continental margin has had a profound influence on the development of the region and has had the effect of generating a series of migratory volcanic arcs and phases of back-arc extension.

The bulk of the Sea of Okhotsk is a nonextensional backarc basin and its sedimentary successions have evolved primarily in response to extensional and wrench tectonics during the Cenozoic.

Acoustic basement, comprising Cretaceous and older rocks, is separated from the overlying Cenozoic section by a regional unconformity associated with movement of the Okhotsk microplate. Rapid subsidence occurred during the Paleogene with numerous rhombic pull-apart basins forming in response to dextral shear.

The Kuril Basin, the oceanic part of the Sea of Okhotsk at the rear of the present Kuril Arc, is triangular in shape, and its origin is related to Middle Miocene rotation.

The principal petroleum play in the region is hydrocarbons reservoired in Miocene sands, sealed by intraformational muds in a structural (generally reactivated or wrench-related anticlinal) setting and sourced from the Paleogene. Best reservoirs are associated with the palaeo-Amur delta system.

Relatively large, structurally simple, rotated normal fault blocks are common throughout the region and offer potential exploration targets.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana