--> Abstract: Tectonic Pattern Offshore of the Sakhalin Shear Zone: Implications on Seep Distribution, by B. Baranov, E. Suess, H. K. Wong, and B. Y. Karp; #90920 (1999).

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BARANOV, BORIS, Institute of Oceanology, Moscow; ERWIN SUESS, GEOMAR Research Center, Kiel; HOW KIN WONG, Dept. Geophysics, University of Hamburg; and BORIS Y. KARP, Pacific Oceanological Institute, Vladivostok

Abstract: Tectonic Pattern Offshore of the Sakhalin Shear Zone: Implications on Seep Distribution

The current structural nature of the plate boundary between the Okhotsk and Amurian plates is characterised by dextral strikeslip motion along the north-southoriented Sakhalin Shear Zone (SSZ) which transects Sakhalin Island. The offshore continuation of the SSZ to the northeast in the Sea of Okhotsk was recently investigated. Although numerous gas seeps have been reported from this area before our studies, their structural control was uncertain.

Analysis of the data obtained showed that the tectonic pattern of this area is characterised by reverse faults that strike in the NW-SE direction. These faults are still active because they can be followed through the upper sediments to the seafloor. The existence of strike-slip faults oriented NE-SW is also suggested. The reverse faults which are widespread in the northern part of the study area cease to exist south of about 54<deg>22<min>N. All known and newly-discovered seeps are located near faults which serve as conduits for gas rising through the sedimentary column to the seafloor. Gas originates here because the gas hydrate zone has become partially unstable. The corresponding layer of BSR was mapped. The tectonic pattern existing in the northern part of the study area is formed under transpressional conditions. Therefore, it is similar to the tectonic pattern in subduction zones where gas conduits are represented by reverse faults and thrusts.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California