Radiometric age of a newly recognized Quaternary volcano: Sasamoriyama Volcano, NE Japan

Abstract

In 2009, it was decided to make the Quaternary with its base at approximately 2.6 million years ago. Corresponding to this revision, Geological Survey of Japan, AIST has published VOLCANOES OF JAPAN (third edition), including Gelasian volcanoes (Nakano et al., 2013). Sasamoriyama Volcano, which is located in the southwestern part of the Fukushima City, NE Japan, is one of such volcanoes. This consists of an andesitic composite edifice in 3.7 to 2.0 Ma. Around the edifice, there are dacite pumice flow deposits, which is newly named as the Horai Pyroclastic Flow Deposit. Fission-track ages of zircons from two samples of this deposit were determined as 1.8±0.3 Ma and 1.9±0.2 Ma, respectively. These ages represent the final activity of Sasamoriyama Volcano.