Recent tectonics of the Eastern Sakhalin Slope

Abstract:

Eastern Sakhalin slope belongs to an active strike-slip boundary between Amur and Okhotsk plates, which is marked by an active tectonics and seismicity. In the east the slope joints to the Okhotsk Sea deep basins.

This continental margin has a complex structural geometry formed by the strike-slip tectonics of the active plate boundary and the deep sea basins formation. Geophysical data in this region show a system of the NS, NE and NW-striking faults in the basement that is covered by sediments of 3-5 km thickness. These faults reflect structure of the strike-slip system at the time of its origin. According to focal mechanism solutions the Sakhalin region is characterized by transition from pure strike-slip motion in the north to compression motion in the south, while Okhotsk Sea deep basins had formed by regional extension. The recent tectonic activity and kinematics of those processes along this continental margin are under discussion

We present results of many years research of the upper part of sedimentary cover structure. Bathymetry and seismic data was interpreted using geomorphology and structural geology approach. Based on the results of the research we distinguished recent fault system, including NS, north-east and north-west faults with significant vertical offset. According to faults kinematics we suggest that this system is formed as a surface manifestation of the recent displacement along deep-seated strike-slip faults. While some of them could be connected to reactivation of the faults originated during the deep-basins formation. Obtained data allows us make suggestions about recent tectonic conditions and lithospheric dynamics In the Eastern Sakhalin slope.