Metamorphic rocks of amphibolite facies from the Atokura Klippe in the Minano town, Kanto Mountains and a K-Ar age determination ( Japan).

Abstract

Regional metamorphic rocks mainly composed of hornlende schists and quartzo-feldspathic rocks of amphibolite facies are exposed in S margin of the Sanbagawa metamorphic belt of the Kanto Mountains. The metamorphic rocks are in contact with quartz diorite and Atokura formation by faults, and intruded by granitic rocks. A K-Ar age of hornblende separated from a hornblende schist is 105+ or -5 Ma, older than those of nearby Sanbagawa and Ryoke metamorphic rocks. The metamorphic rocks studied here are one of the geologic units belonging to the Atokura Nappe.-English summary