457 research outputs found

    Linking Tarim between South China and North India in the periphery of Supercontinent Rodinia

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    The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / 3F Seminar room, National Institute of Polar Researc

    〈Original Paper〉 Field occurrence of cordierite gneiss and related ultrahigh-temperature granulites from the Achankovil Shear Zone, southern India

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    Provenance of Garnet in the Neoarchean Verbaard granitoid gneiss: A case study from Beit Bridge Complex, Cetral Zone, Southern Africa

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    The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researc

    Petrological study of Archean high-grade metamorphic rocks in the Northern marginal zone of the Limpopo Belt, Zimbabwe

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    筑波大学University of Tsukuba博士(理学)Doctor of Philosophy in Science1992【要旨】thesi

    The origin and role of fluid associated with lower crustal metamorphism

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    科学研究費助成事業(科学研究費補助金)研究成果報告書:基盤研究(B)2008-2011課題番号:2034014

    Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation

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    We report new petrological, phase equilibria modeling, and fluid inclusion data for pelitic and mafic granulites from Rundvågshetta in the highest-grade region of the Neoproterozoic Lützow-Holm Complex (LHC), East Antarctica, and provide unequivocal evidence for fluid-rock interaction and high-temperature metasomatism in the presence of brine fluid. The studied locality is composed dominantly of well-foliated pelitic granulite (K-feldspar + quartz + sillimanite + garnet + ilmenite) with foliation-parallel bands and/or layers of mafic granulite (plagioclase + orthopyroxene + garnet + ilmenite + quartz + biotite). The boundary between the two lithologies is defined by thin (about 1–20 cm in thick) garnet-rich layers with a common mineral assemblage of garnet + plagioclase + quartz + ilmenite + biotite ± orthopyroxene. Systematic increase of grossular and decrease of pyrope contents in garnet as well as decreasing Mg/(Fe + Mg) ratio of biotite from the pelitic granulite to garnet-rich rock and mafic granulite suggest that the garnet-rich layer was formed by metasomatic interaction between the two granulite lithologies. Phase equilibria modeling in the system NCKFMASHTO demonstrates that the metasomatism took place at 850–860 °C, which is slightly lower than the peak metamorphism of this region, and the modal abundance of garnet is the highest along the metapelite–metabasite boundary (up to 40%), which is consistent with the field and thin section observations. The occurrence of brine (7.0–10.9 wt.% NaCleq for ice melting or 25.1–25.5 wt.% NaCleq for hydrohalite melting) fluid inclusions as a primary phase trapped within plagioclase in the garnet-rich layer and the occurrence of Cl-rich biotite (Cl = 0.22–0.60 wt.%) in the metasomatic rock compared to that in pelitic (0.15–0.24 wt.%) and mafic (0.06–0.13 wt.%) granulites suggest infiltration of brine fluid could have given rise to the high-temperature metasomatism. The fluid might have been derived from external sources possibly related to the formation of major suture zones formed during the Gondwana amalgamation

    Resolving orogenic events in construction of the Lutzow-Holm Complex, east Antarctica

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    第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日(木) 国立極地研究所 2階大会議

    ‘Okunen’ in a long, hot orogen: a timeline of tectonometamorphic activity in southern LützowHolm Bay

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    第3回極域科学シンポジウム/第32回極域地学シンポジウム 11月30日(金) 統計数理研究所 3階セミナー

    The Magondi Belt in southern Africa: Implication for Paleoproterozoic crustal evolution in the northwestern Zimbabwe Craton

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    The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / 3F Seminar room, National Institute of Polar Researc
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