Item type |
紀要論文(ELS) / Departmental Bulletin Paper(1) |
公開日 |
2001-07-01 |
タイトル |
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言語 |
en |
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タイトル |
Petrography and mineral chemistry of high-grade pelitic gneisses and related rocks from Namaqualand, South Africa |
言語 |
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言語 |
eng |
キーワード |
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言語 |
en |
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主題Scheme |
Other |
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主題 |
granulite |
キーワード |
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言語 |
en |
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主題Scheme |
Other |
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主題 |
high temperature metamorphism |
キーワード |
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言語 |
en |
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主題Scheme |
Other |
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主題 |
Namaqualand |
キーワード |
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言語 |
en |
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主題Scheme |
Other |
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主題 |
paragneiss |
キーワード |
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言語 |
en |
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主題Scheme |
Other |
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主題 |
pelitic gneiss |
資源タイプ |
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資源タイプ識別子 |
http://purl.org/coar/resource_type/c_6501 |
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資源タイプ |
departmental bulletin paper |
ページ属性 |
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内容記述タイプ |
Other |
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内容記述 |
P(論文) |
著者名(英) |
Hokada, Tomokazu
Motoyoshi, Yoichi
Hiroi, Yoshikuni
Shimura, Toshiaki
Yuhara, Masaki
Shiraishi, Kazuyuki
Grantham, Geoffrey H.
Knoper, Mike W.
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著者所属(英) |
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en |
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National Institute of Polar Research/National Institute of Polar Research/Department of Earth Sciences, Faculty of Science, Chiba University/Department of Geology, Faculty of Science, Niigata University/Department of Earth System Science, Faculty of Science, Fukuoka University/National Institute of Polar Research/Council for Geoscience/Department of Geology, Rand Afrikaans University |
抄録(英) |
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内容記述タイプ |
Other |
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内容記述 |
Four different types of paragneisses, (1) ordinary pelitic gneiss, (2) sapphirine-bearing aluminous gneiss, (3) osumilite-bearing magnesian gneiss, and (4) quartz-magnetite-rich ferruginous gneiss, occur in the Namaqualand Metamorphic Complex in South Africa. They are examined with respect to their mineral parageneses and mineral chemistries for assessing chemical evolution during high temperature metamorphism. (1) Ordinary pelitic gneisses show amphibolite to granulite facies mineral parageneses composed of biotite, sillimanite, cordierite, garnet and spinel with or without orthopyroxene. Other rock types (2)∿ (4), occurring as layers or blocks in pelitic gneiss, granitic orthogneiss or mafic granulite, show characteristic mineral parageneses : (2) Aluminous gneiss is characterized by quartz-free silica-undersaturated mineral parageneses, and contains porphyroblastic clots of sapphirine-spinel-corundum aggregate. (3) Osumilite-bearing magnesian gneiss is composed mainly of quartz, plagioclase, cordierite and osumilite which is mostly replaced by a fine-grained symplectite of cordierite-K-feldspar-quartz-orthopyroxene. Biotite, spinel and orthopyroxene are minor. (4) Ferruginous gneiss contains a large volume of magnetite accompanying quartz, sillimanite and spinel. Feldspar is typically lacking. Biotite in paragneisses contains a varying amount of fluorine, up to 5.8wt%, having no systematic relation to whether it coexists with orthopyroxene or not. Geothermobarometries for coexisting garnet and orthopyroxene yield metamorphic conditions around 850℃ and 0.5GPa. Orthopyroxene contains high (Al)_2O_3,up to 8.5wt%, and is probably formed by the dehydration melting of biotite at the peak of metamorphism. ZnO contents of spinel in pelitic, ferruginous and magnesian gneisses range from 0.3 to 13.7wt%, whereas those in the sapphirine-bearing aluminous gneisses are less than 0.5wt%. |
雑誌書誌ID |
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収録物識別子タイプ |
NCID |
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収録物識別子 |
AA00733561 |
書誌情報 |
Memoirs of National Institute of Polar Research. Special issue
巻 55,
p. 105-126,
発行日 2001-07
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