Abstract
Since 1967, the Basic Map of the Sea Project has been carried out by the Japanese Hydrographic Department. The results of this survey have been published as the bathymetric chart, submarine structural map, total magnetic intensity chart and gravity anomaly chart of 1/200, 000 in scale. In this paper, the results of survey from 1967 to 1968 were compiled into the bathymetric chart and submarine geological map of 1/500, 000 in scale.
In early Miocene Epoch, many sedimentary basins were formed in the environs of the western part of the Northeast Japan and the continental borderland in the sea. In late Miocene, the acoustically transparent sediments deposited in the sea of comparatively uniform sedimentary environment.
In early Pliocene, the differentiation of sedimentary basin and the tectonic movement accompanying folding and faulting of NE-SW direction began to take place.
In late Pliocene, intense movement of NNE-SSW direction which formed folding and faulted blocks in the Sado Ridge and Mogami Trough, had occurred and the outline of submarine relieves in today were accomplished.
