Petrographic properties of Late Pleistocene tephra layers of the Akagi Volcano, northern Kanto, central Japan

Abstract

    Petrographic properties of 12 layers of Late Pleistocene tephra which can be observed at the southeastern foot of the Akagi Volcano, Gunma Prefecture, central Japan are described. Detailed examination of these tephra layers reveals that Ag-Nm2, Ag-UP, Ag-KP tephras comprise a few fall units representing different refractive indices of orthopyroxene and hornblende crystal grains from each other. Furthermore, Ag-MzP3, Ag-MzP2, Ag-Nm2, and Ag-UP tephras represent largely different refractive indices from the property of the majority of the examined tephras. These petrographic features are important for identifi cation and correlation of these tephra layers.