岡山大学 地球科学研究報告
Published by Okayama University Earth Science Reports Editorial Committee

A note on compositional variation of olivine and pyroxene in thermally metamorphosed ultramafic complexes from SW Japan

Abstract
This short article presents some diagrams showing the compositional variations of primary and metamorphic olivine, orthopyroxene and clinopyroxene in peridotites and serpentinites from thermally metamorphosed ultramafic complexes in SW Japan. In contrast to olivine, which shows a gradual change of chemical composition corresponding with metamorphic grade, orthopyroxene and clinopyroxene show clear differences in composition between primary and metamorphic phases. Compared with primary pyroxenes, even though their compositions could be variable depending on original rock composition, metamorphic orthopyroxene and metamorphic clinopyroxene is clearly deficient in Cr(2)O(3) and CaO, and in Cr(2)O(3) and Al(2)O(3), respectively. These characteristics are useful for the discrimination between the pyroxenes of different origin.
Keywords
chemical composition
olivine
orthopyroxene
clinopyroxene
metaperidotite
ISSN
1340-7414
NCID
AN10506284
NAID