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ID 13917
Eprint ID
13917
フルテキストURL
Thumnail ESR_4_33.pdf 1.11 MB
タイトル(別表記)
Ferroglaucophane schist from the Ohsa-yama srea, Okayama Prefecture, Japan
著者
野坂 俊夫 岡山大学理学部地球科学科
抄録
A ferroglaucophane schist occurs in fault contact with serpentinites at the Ohsa-yama area, Southwest Japan. It consists of albite, ferroglaucophane and actinolite with small amounts of stilpnomelane, sphene, apatite and K-feldspar. Petrological studies reveal that the schist was originally igneous rock of felsic or intermediate composition and has suffered two stages of metamorphism : ferroglaucophane has been formed at the first stage and actinolite at the second stage. In a basic schist from the same outcrop that the ferroglaucophane schist occurs, tremolitic amphibole instead of alkali amphibole has been formed along with chlorite, phengite and albite. Such a difference in mineral association between the schists is ascribed to a difference in whole rock composition, particu-larly in Fe/Mg ratio. Some of the schists from th Ohsa-yama area characteristically contain glaucophane or ferroglaucophane and have low Fe2O3/FeO ratios, forming a striking contrast to the crossite schists that commonly occur in the so-called "Sangun metamorphic terrane". These facts suggest that the alkali amphiboles of the Ohsa-yama schists were formed under higher P/T and more reducing conditions than those of the regional metamrphic rocks. On the other hand, development of the second-stage actinolite in the ferroglaucophane schist is consistent with the meta-morphic parageneses of greenschists from adjacent areas. Consequently the ferroglaucophane schist is considered one of the tectonic blocks that were captured by mobile serpentinites and have suffered the regional metamor-phism after the emplacement of the serpentinites into the present geologic position.
キーワード
ferroglaucophane
petrology
tectonic block
serpentinite
high P/T metamorphism,
Ohsa-yama
Sangun metamorphic terrane
Southwest Japan
発行日
1997-09-20
出版物タイトル
Okayama University Earth Science Report
出版物タイトル(別表記)
岡山大学地球科学研究報告
4巻
1号
出版者
岡山大学理学部地球科学教室
出版者(別表記)
Department of Earth Sciences Faculty of Science, Okayama University
開始ページ
33
終了ページ
40
ISSN
1340-7414
NCID
AN10506284
資料タイプ
紀要論文
言語
Japanese
著作権者
岡山大学地球科学研究報告編集委員会
論文のバージョン
publisher
査読
無し
Eprints Journal Name
esr