Paleomagnetic polarity of the pyroclastic flow deposits from the Hakkoda Caldera, Northeast Japan

Abstract

The paleomagnetic directions of four pyroclastic flow deposits from the Hakkoda Caldera, Northeast Japan, were determined using both progressive thermal and alternating field demagnetization. The Hakkoda second-and first-stage pyroclastic flow deposits acquired remanent magnetization during the Brunhes Chron, while the Hakkoda zero-stage and Osegawa pyroclastic flow deposits acquired it during the Matuyama Chron. Our results support a recent tephrochronologic view that the Hakkoda first-stage pyroclastic flow deposit is the proximal source pyroclastic flow of the widespread, early Middle Pleistocene, Hakkoda-Kokumoto tephra bed.