(K-Ar ages of muscovite from greenstone in the Ino formation and schist blocks associated with the Kurosegawa tectonic zone near Kochi City, central Shikoku.)

Y. Ueda, T. Nakajima, K. Matsuoka, S. Maruyama

    研究成果査読

    9 被引用数 (Scopus)

    抄録

    The Kurosegawa tectonic zone is a serpentinite melange zone in which various kinds of tectonic blocks occur. Muscovites coexisting with high-P minerals gave ages of 352-394 m.y. They indicate that so-called semischists were neither metamorphosed at the time of formation of the Kurosegawa tectonic zone, nor by the Sanbagawa metamorphism, but show a distinct metamorphic event older than Middle Carboniferous. This is the oldest radiometric age among glaucophane schists in Japan. Muscovites from the schist xenoliths of albite-epidote amphibolite facies grade were dated at 317 and 327 m.y. by the K/Ar method. Hornblende and barroisite are sometimes replaced by actinolite or riebeckite along their cleavages or irregular cracks. Muscovite is also deformed to show kink-band folding and is chloritized parallel to cleavage or along irregular cracks. Therefore, the values 317 and 327 m.y. may not show the time of albite-epidote amphibolite facies metamorphism, but are older than those of the Sanbagawa schists.-M.Ak.

    寄稿の翻訳タイトルJapanese with English abstract
    本文言語Japanese
    ページ(範囲)230-233
    ページ数4
    ジャーナルJournal of the Japanese Association of Mineralogists, Petrologists & Economic Geologists
    75
    7
    出版ステータスPublished - 1月 1 1980

    ASJC Scopus subject areas

    • 環境科学一般
    • 地球惑星科学一般

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