LREE-enriched mafic gneiss and meta-ultramafic rock from Tonagh Island in the Napier Complex, East Antarctica

• OWADA M.

  Department of Earth Sciences, Yamaguchi University

• Osanai Yasuhito

  Department of Earth Sciences, Okayama University

• Tsunogae Toshiaki

  Department of Earth Sciences, Shimane University

• Toyoshima Tsuyoshi

  Graduate School of Science and Technology, Niigata University

• Hokada Tomokazu

  National Institute of Polar Research

• Crowe Warwick A.

  Department of Geology and Geophysics, University of Western Australia

抄録

Mafic gneisses and meta-ultramafic rocks are exposed on Tonagh Island These rocks are high-Mg composition and have undergone ultrahigh-temperature metamorphism Most of the mafic gneisses and the meta-ultramafic rocks occur as intercalated layers or lenses within the quartzo-feldspathic gneisses Some of the mafic gneisses and the meta-ultramafic rocks locally cut the layers or foliations of neighboring quartzo-feldspathic gneisses, suggesting that these mafic gneisses and meta-ultramafic rocks were originally intrusive rocks Major and trace element compositions of the mafic gneisses and the meta-ultramafic rocks resemble those of komatiitic basalt to komatiite from the Archaean greenstone belt Light REE-enriched and flat patterns are recognized in the mafic gneisses and meta-ultramafic rocks although the REE pattern of the deformed sample is convex upward In the Mt Riiser-Larsen region situated 40 km northeast from Tonagh Island, it has been found in a previous study that the LREE-enriched mafic gneisses and meta-ultramafic rocks have been derived from komatiitic rocks whose chemical trends show magmatic variations Therefore, the LREE-enriched patterns of mafic gneisses and ultramafic rocks on Tonagh Island and in the Mt Riiser-Larsen region could be inherited from the chemical nature of original rocks prior to undergoing ultrahigh-temperature metamorphism The LREE-enriched pattern cannot be explained by interaction between an LREE-flat parental magma and an LREE-enriched crustal material m terms of geochemical constraints Hence, the LREE-enriched and flat types of the mafic gneisses and the meta-ultramafic rocks on Tonagh Island would have been derived from different source mantles with respect to LREE signatures

収録刊行物

• Polar Geoscience

  Polar Geoscience 13 86-102, 2000

  国立極地研究所

キーワード

• Archaean
• Napier Complex
• mafic gneiss and meta-ultramafic rock
• REE geochemistry
• source mantle

詳細情報

• CRID: 1570009751900149888
• NII論文ID: 110000035091
• NII書誌ID: AA1130866X
• ISSN: 13443194
• 本文言語コード: en
• データソース種別:
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