阿蘇カルデラ内北西部ボーリングコア基盤岩類の岩石学的特徴およびK‐Ar年代  [in Japanese] Petrological characteristics and K-Ar age of borehole core samples of basement rocks from the northwestern caldera floor of Aso, central Kyushu  [in Japanese]

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Author(s)

    • 三好 雅也 Miyoshi Masaya
    • 京都大学大学院理学研究科附属地球熱学研究施設|現所属:東京大学地震研究所 Beppu Geothermal Research Laboratory, Institute for Geothermal Sciences, Kyoto University|Present address: Earthquake Research Institute, The University of Tokyo
    • 湯口 貴史 Yuguchi Takashi
    • 熊本大学大学院自然科学研究科|現所属:独立行政法人日本原子力研究開発機構 Graduate school of Science and Technology, Kumamoto University|Present address: Japan Atomic Energy Agency
    • 森 康 Mori Yasushi
    • 北九州市立自然史・歴史博物館 Kitakyushu Museum of Natural History and Human History
    • 荒川 洋二 Arakawa Yoji
    • 筑波大学大学院生命環境科学研究科 Graduate School of Life and Environmental Sciences, University of Tsukuba

Abstract

We report on the petrography, whole-rock chemical composition, Sr isotope ratio, and K–Ar age of borehole core samples (310–630 m depth) of basement rocks from the northwestern caldera floor of Aso volcano, central Kyushu. The basement core is composed of granodiorite and hornfelsic pelitic-psammitic schist. Both the granodiorite and schist contain mainly quartz, plagioclase, K-feldspar, biotite, and opaque minerals. The granodiorite also contains rare hornblende. The schist has a banded structure, and the schist and granodiorite are migmatitic at a depth of 553 m. The granodiorite yields a K–Ar biotite age of 105 Ma. The petrographic characteristics and age of the granodiorite are similar to those of other basement granitic rocks in and around the Aso area (93–108 Ma). These observations indicate that the basement granitoids of the Aso area cooled at the same time as Cretaceous granitoids in central Kyushu.

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 117(10), 585-590, 2011

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130001915375
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • ISSN
    0016-7630
  • NDL Article ID
    023192476
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
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