The Clinopyroxenes of the Miyamori ultrabasic intrusive body, Kitakami mountainland

Abstract

Nine clinopyroxenes, separated from serpentinized peridotite, olivine clinopyroxenites, clinopyroxenite, hornblened clinopyroxenite and clinopyroxene hornblendites of the Miyamori ultrabasic intrusive, Kitakami mountainland, have been chemically analysed and optically determined. These clinoproxenes have a range from Ca_47.1 Mg_49.1 Fe_3.8 to Ca_48.6 Mg_35.2 Fe_16.2. The trend line of the clinopyroxene crystallization takes a course from diopside field to salite field. The Al proportions in the clinopyroxenes are thought to be mainly controlled by chemical composition of the magma from which they are crystallized in the case of the Miyamori ultrabasic body as well as the Hayachine ultrabasic complex. Some considerations on the chemical nature of clinopyroxenes are shortly discussed.