The tonalite and its associated fine-grained basic in the southern part of Okushibetsu district, Hokkaido

Abstract

The tonalite and the fine-grained basic rocks occur in the southern part of Okushibetsu district, Hokkaido. The tonalites are the cummingtonite tonalite and the kalifeldspar bearing hypersthene cummingtonite tonalite. The finegrained basic rocks are the biotite bearing hypersthene brown hornblende plagioclase rock, the biotite bearing hypersthene quartz plagioclase pale brown hornblende rock, the green hornblende plagioclase rock, and the quartz biotite plagioclase brown hornblende rock.
Judging from the observations of these rocks under the microscope, they are of the metamorphic origins which came from the biotite rich coarse rock or the biotite rich hornfelsic rock.