Study of felsic metamorphic rocks and its associated inclusions which lie in gabbro-diorite at the up-stream of Horoman river, Hidaka piovince, Hokkaido (Appendix)

Abstract

The said rocks include scaly magnetite, hematite, pyrrhotite, chalcopyrite, and limonite as the accessory minerals. It is observed that these opaque minerals are deposited from the early to later stage, replacing the biotites. In the basic inclusions of felsic metamorphic rocks or in micro or medium gabbrodiorite, the volume per cent of scaly magnetite and pyrrhotite is higher than in felsic metamorphic rocks. Chalcopyrite always occurs, but a little in volume Hematite also occurs a little, in felsic metamorphic rocks. Limonite is also formed in some rocks as pseudomorph after pyrrhotite. At the stage of the scaly magnetite, the clouding and cleaning of plagioclase and crystallization of hornblende, occur instead of forming biotite, accompanying basification of plagioclase, and at the simultaneous or a little later, sulphides are fixed as pyrrhotite or chalcopyrite. The geologic conditions for forming these rocks are discussed in the present paper.