Correlation of the Early Pleistocene Tugm Tephra Bed in the Niigata region and Kd18 Tephra Bed in the Boso Peninsula to the Ashino Pyroclastic Flow Deposit in the Aizu region, northeast Japan

Abstract

The early Pleistocene Tugm Tephra Bed in the Niigata region and the Kd18 Tephra Bed in the Boso Peninsula were correlated to the Ashino Pyroclastic Flow Deposit in the Aizu region. They contain bubble-junction type glass shards and high quartz in common. Chemical composition of glass shard and orthopyroxene (Mg#=63.6-66.0) of these tephra is also coincident. These tephras are expected to be found as marker beds in Japan.