Item type |
紀要論文(ELS) / Departmental Bulletin Paper(1) |
公開日 |
1993-09-01 |
タイトル |
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タイトル |
CONTRASTING MINERAL ASSOCIATIONS BETWEEN TWO WOLLASTONITE-BEARING CALC-SILICATE GNEISSES, EASTERN SØR RONDANE MOUNTAINS, ANTARCTICA |
言語 |
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言語 |
eng |
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 |
ID登録 |
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ID登録 |
10.15094/00002719 |
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ID登録タイプ |
JaLC |
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) |
ASAMI, Masao
GREW, Edward S.
MAKIMOTO, Hiroshi
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著者所属(英) |
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en |
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Department of Geological Sciences, College of Liberal Arts, Okayama University |
著者所属(英) |
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en |
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Department of Geological Sciences, University of Maine |
著者所属(英) |
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en |
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Geological Survey of Japan |
抄録(英) |
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内容記述タイプ |
Other |
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内容記述 |
Calc-silicate gneisses are found at Austhamaren and Eremitten in the polymetamorphic granulite-and amphibolite-facies metamorphic rocks of the eastern Sør Rondane Mountains. The diagnostic assemblage in the Austhamaren calc-silicate is garnet (Grt)-quartz (Qtz)-wollastonite (Wo)-calcite (Cal), whereas Wo-plagioclase (Pl)-scapolite (Scp)-Qtz and Wo-Cal-Scp-Qtz are characteristic assemblages in the Eremitten gneiss. Wollastonite and calcite are nearly end member CaSiO_3 and CaCO_3. The other major phases approach the calcic end members : garnet is 80-91mole% grossular, plagioclase is An_<88-94>, and scapolite 77-83mole% meionite. Clinopyroxene is hedenbergite (Fe/(Fe+Mg)=0.50-0.67). The reactions Grt+Qtz=Wo+An and Grt+CO_2=Wo+Scp+Cal relate the assemblages in the Austhamaren and Eremitten samples. The two assemblages could be interepreted to result from a regional pressure decrease from Austhamaren in the north to Eremitten in the south. An alternative interpretation is that the Eremitten Wo-Scp assemblages formed at somewhat higher CO_2 activities, and Wo-An, at a slightly higher bulk Na/Ca ratio, compared to the Austhamaren assemblage. X_<CO_2>/(CO_2+H_2O) in the associated fluid phase) is estimated to have been buffered at <0.3 in the Eremitten rock and at 0.1-0.2 in the Austhamaren rock (for T=760-800℃, P=7-8kbar). X_<CO_2> remained low during a nearisobaric temperature decrease to T≤600℃ following peak conditions at Eremitten when garnet selvages developed around wollastonite, scapolite, and plagioclase and scapolite was partially replaced by Pl+Cal+K-feldspar symplectite. |
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 |
AA1072335X |
書誌情報 |
Proceedings of the NIPR Symposium on Antarctic Geosciences
巻 6,
p. 57-71,
発行日 1993-09
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出版者 |
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出版者 |
National Institute of Polar Research |