58 research outputs found

    Zircons in metacarbonate rocks from Sør Rondane Mountains, East Antarctica

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    第6回極域科学シンポジウム[OG] 地圏11月16日(月) 国立極地研究所3階セミナー

    Comparison of chemically estimated depositional ages with zircon SHRIMP ages from metacarbonate rocks in the Sør Rondane Mountains, East Antarctica

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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) 国立極地研究所 3階ラウン

    Neoproterozoic to Cambrian granitoids of northern Mozambique and Dronning Maud Land 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

    Terrane correlation between Antarctica, Mozambique and Sri Lanka; comparisons of geochronology, lithology, structure and metamorphism and possible implications for the geology of southern Africa and Antarctica

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    Analysis of new lithological, structural, metamorphic and geochronological data from extensive mapping in Mozambique permits recognition of two distinct crustal blocks separated by the Lurio Belt shear zone. Extrapolation of the Mozambique data to adjacent areas in Sri Lanka and Dronning Maud Land, Antarctica permits the recognition of similar crustal blocks and allows the interpretation that the various blocks in Mozambique, Sri Lanka and Antarctica were once part of a mega-nappe, forming part of northern Gondwana, which was thrust-faulted c. 600 km over southern Gondwana during amalgamation of Gondwana at c. 590-550 Ma. The data suggest a deeper level of erosion in southern Africa compared with Antarctica. It is possible that this thrust domain extends, through the Zambezi Belt or Valley, as far west as the Damara Orogen in Namibia with the Naukluft nappes in Namibia, the Makuti Group, the Masoso Suite in the Rushinga area and the Urungwe klippen in northern Zimbabwe, fitting the mega-nappe pattern. Erosional products of the mountain belt are now represented by 700-400 Ma age detrital zircons present in the various sandstone formations of the Transantarctic Mountains, their correlatives in Australia, as well as the Urfjell Group (western Dronning Maud Land) and probably the Natal Group in South Africa

    Sulfur isotope study of Chitradurga schist belt, Archean Dharwar craton, India.

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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階大会議室前フロ

    Electron micoprobe (EMP) dating on monazite from Forefinger Point granulites, East Antarctica: Implication for Pan-African overprint

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    Electron microprobe (EMP) dating on monazite in granulite-facies rocks from Forefinger Point,East Antarctica, yielded dominant ages of ~500 Ma on matrix monazites.They are associated with secondary cordierite, biotite and sapphirine, formed during nearly isothermal decompression after the high P-T assemblages involving garnet, orthopyroxene and sillimanite. Older ages around 750 1 000 Ma are detected in monazite cores and in monazite inclusions in garnet porphyroblast. Combining the available age data and the reaction textures, it becomes evident that the Forefinger Point granulites have been overprinted by a granulite-facies decompressional event of Pan-African age. Moreover, EMP monazite dating imply that the Forefinger Point granulites have experienced at least two stages of metamorphic evolution

    Feldspar in felsic orthogneiss as indicator for UHT crustal processes

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