The Izanagi Plate was an ancient tectonic plate, which began subducting beneath the Okhotsk section of the North American Plate during 130 - 100 Ma. The rapid plate motion of the Izanagi Plate caused the northward drift of north-west Japan and the outer zone of south-west Japan. Sanbagawa metamorphic rocks were formed in the eastern margin of the drifting land mass, while Abukuma metamorphic rocks were formed in its western margin. At approximately 95 Ma, the Izanagi Plate was completely subducted and replaced by the western Pacific Plate which also subducted in the north-western direction. Subducted-related magmatism took place near the Ryoke belt. No marked tectonics occurred in the Abunkuma belt after the change of the subducted plate.