TheIzanagi plate (named after the Shinto godIzanagi) was an ancienttectonic plate, which begansubducting beneath theOkhotsk plate 130–100Ma (million years ago). The rapid plate motion of the Izanagi plate caused northwestJapan and the outer zone of southwest Japan to drift northward. High-pressuremetamorphic rocks were formed at the eastern margin of the drifting land mass in the Sanbagawa metamorphicbelt, while low-pressure metamorphic rocks were formed at its western margin in the Abukuma metamorphic belt. At approximately 55 Ma, the Izanagi Plate was completely subducted and replaced by the westernPacific plate, which also subducted in a northwestern direction. Subduction-relatedmagmatism took place near theRyoke belt. No marked tectonics occurred in the Abukuma belt after the change of the subducted plate.
The discovery of an extinctJurassic–Cretaceous spreading system in the northwest Pacific led to the introduction of the extinctKula plate in 1972. The Izanagi plate was subsequently introduced in 1982 to explain the geometry of this spreading system.[1] Knowledge of the former Izanagi plate is limited toMesozoicmagnetic lineations on the Pacific plate that preserve the record of this subduction.[2]
