Tectonic Rotation of the Kanto Mountains, Related with the Opening of the Japan Sea and Collision of the Tanzawa Block since Middle Miocene

Abstract

Paleomagnetic measurements were made on the early Miocene marine sediments in the Chichibu Basin of the Kanto Mountains, Central Japan. The mean paleomagnetic direction, D=94°, I=53° (α₉₅=8.3°), indicates that the Kanto Mountains have not changed their latitude significantly, but have rotated clockwise through about 90° since the middle Miocene. The rotation can be explained by the opening of the Japan Sea and the collision of the Tanzawa Block.