書誌事項
- タイトル別名
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- Ferroglaucophane schist from the Ohsa-yama srea, Okayama Prefecture, Japan
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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.
収録刊行物
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- Okayama University Earth Science Report
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Okayama University Earth Science Report 4 (1), 33-40, 1997-09-20
岡山大学理学部地球科学教室
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詳細情報 詳細情報について
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- CRID
- 1390009224581088000
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- NII論文ID
- 120002310538
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- NII書誌ID
- AN10506284
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- ISSN
- 13407414
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- 本文言語コード
- ja
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- データソース種別
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- JaLC
- IRDB
- CiNii Articles