Item type |
紀要論文(ELS) / Departmental Bulletin Paper(1) |
公開日 |
1994-09-01 |
タイトル |
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タイトル |
RELICT SAPPHIRINE IN PYROPIC GARNET FROM THE EASTERN SØR RONDANE MOUNTAINS, ANTARCTICA |
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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 |
10.15094/00002765 |
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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) |
記事種別(英) |
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en |
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ABSTRACT |
著者名よみ |
アサミ, マサオ
マキモト, ヒロシ /
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著者名(英) |
ASAMI, Masao
MAKIMOTO, Hiroshi
GREW, Edward S.
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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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Geological Survey of Japan |
著者所属(英) |
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en |
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Department of Geological Sciences, University of Maine |
抄録(英) |
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内容記述タイプ |
Other |
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内容記述 |
Sapphirine-bearing biotitic schist forms a reaction zone between an ultramafic lens and its host biotite-hornblende gneiss at Balchenfjella, which is underlain by migmatitic complex metamorphosed under granulite-facies conditions in the Late Proterozoic and under amphibolite-facies conditions in the Early Paleozoic. This schist consists of porphyroblastic garnet, the core of which is compositionally homogeneous pyrope-almandine (X_<Mg>=Mg/(Fe+Mg)≅0.50) surrounded by an almandine rim (X_<Mg>≅0.27), biotite (X_<Mg>=0.70-0.73), plagioclase (An_<75-87>), spinel (X_<Mg>=0.26-0.36), corundum, rutile and zircon. In addition, individual garnet porphyroblasts enclose different mineral associations in the magnesian cores as follows : (A) sapphirine (X_<Mg>=0.75-0.85), commonly with kyanite, and, locally, with spinel (X_<Mg>=0.50-0.68), (B) kyanite only, and (C) gedrite (X_<Mg>=0.75-0.78)+quartz aggregates. The mineral associations sapphirine+kyanite±spinel and gedrite+quartz±kyanite are inferred to be relict assemblages of the prograde P-T path, and the magnesian garnet cores to have been homogenized during the granulite-facies event. Differences in the associations are presumed to have resulted from pre-metamorphic chemical heterogeneity in the precursor to the biotitic schist. These mineral associations suggest a clockwise prograde P-T trajectory entirely within the kyanite field; the assemblage sapphirine+kyanite might have been stable as T approached 700℃ constraining P to be at least 8 kbar. Further increase in temperature was accompanied by a small decrease in P to the 7-8 kbar (at T=760-800℃) estimated for peak conditions in the granulite-facies by M. ASAMI et al. (Proc. NIPR Symp. Antarct. Geosci., 6,57,1993). The relict sapphirine-kyanite assemblages in the Sør Rondane Mountains are similar to those reported from the Luzow-Holm Bay complex, Antarctica, and the Highland Complex, Sri Lanka (e.g. Y. OGO et al. : Recent Progress in Antarctic Earth Science, ed. by Y. Yoshida et al. Tokyo, Terra Sci. Publ., 75,1992), suggesting similarities in the P-T evolution of the three areas. |
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 7,
p. 179,
発行日 1994-09
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出版者 |
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出版者 |
National Institute of Polar Research |