Major strike-slip faults and their bearing on spreading in the japan sea

Abstract

The authors emphasize the important role of the large scale strike-slip faults in the tectonic history of the circum-Japan Sea region including the origin of the Japan Sea Basins. NE-SW to NNE-SSW trending faults in the region were formed by the intense compression from the south which corresponds to the “pulse” suggested by Larson and Pitman (1972). NS to NNW-SSE trending faults in Northeast Japan were formed one after another from east to west by the left-lateral simple shear force induced by the subduction of the peculiar transform fault between the Kula and Tethys plates. Subduction of the seamount chain on the peculiar transform fault formed NW-SE trending faults and the cusp structure in the Kanto region. The subduction of the Kula-Pacific and Tethys ridges produced the acidic igneous activities of the Cretaceous to Paleogene in the Asiatic continental margin. Japan Sea Basins were formed in the Paleogene time by the southward drift of the western part of Japan bounded on the east by the Tanakura shear zone and on the west by the Tsushima fault, both of which had already been formed as left-lateral faults in the Cretaceous time. © 1978, The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan. All rights reserved.