Petrology of the Miocene mafic volcanic rocks distributed in Utsunomiya, Kanuma and Motegi, central Japan

Abstract

 Two types of Miocene volcanic rocks are distributed in Utsunomiya, central Japan. Andesite and rhyolite are intercalated with Kazamiyamada Formation, in the lower, and Oya Formation, in the upper, respectively. The Kazamiyamada formation derives subaerial volcanism, and in contrasts the Oya formation formed by submarine volcanic eruption. These igneous activities correspond to the opening event of Japan Sea.
 On the other hand, Miocene volcanic rocks distributed are Kanuma and Motegi areas, around of the Utsunomiya area.
 This study compared the Kazamiyamada andesites with the Kanuma and Motegi mafic volcanic rocks.