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

Petrography of primary peridotites from the Ohsa-yama area, Okayama Prefecture

野坂 俊夫 Department of Earth Sicences, Faculty of Science Okayama University
柴田 次夫 Department of Earth Sicences, Faculty of Science Okayama University
Thumnail ESR_1_1.pdf 418 KB
抄録
Ultramafic rocks exposed around Mt. Ohsa(= Ohsa-yama), Okayama prefecture, designated as "Ohsa-yama ultramafic body" all together, are one of the Alpine-type peridotites in the Sangun metamorphic belt. They are intensely serpentinized and locally suffered contact metamorphism by younger granitic intrusions. In a por-tion of the ohsa-yama body where it has been affected by the contact metamorphism, the constituent minerals, texture and structure of primary ultramafic rocks have been locally preserved. Petrographic studies revead that the primary ultramafic rocks of the ohsa-yama body consist domimantly of dunite and harzburgite possessing no obvious layering, and their constituent minerals are similar in composition to those of the Tari-Misaka and Ashidachi ultramafic bodies. These features indicate that unlike the Ochiai-Hokubo body, the Ohsa-yama ultra-mafic body belongs to the "massive group" of the Arai's (1980) classification.
キーワード
petrography
dunite
harzburgite
massive ultramafic body
ISSN
1340-7414
NCID
AN10506284