Field occurrence and chemical composition of the melanocratic porphyritic facies of the Yusubaru Granite, northern Kyushu, Southwest Japan

DOI
  • YUHARA Masaki
    Kyushu Branch of the Association for the Geological Collaboration in Japan; Department of Earth System Science, Faculty of Science, Fukuoka University
  • NISHI Eriko
    Kawasaki Geological Engineering Co., Ltd.
  • KIYOURA Kairi
    Wajinkai Hospital, Medical Corporation Wjinkai
  • KAMEI Atsushi
    Department of Earth Science, Interdisciplinary Faculty of Science and Engineering
  • KAWANO Yoshinobu
    Department of Environment Systems, Faculty of Geo-environmental Science, Rissho University
  • OKANO Osamu
    Department of Earth Sciences, Faculty of Science, Okayama University
  • HAYASAKA Yasutaka
    San-yo Branch of the Association for the Geological Collaboration in Japan; Earth and Planetary Systems Science Program, Graduate School of Advanced Science and Engineering, Hiroshima University

Bibliographic Information

Other Title
  • 北部九州白亜紀花崗岩類，油須原花崗岩優黒質斑状岩相の産状と化学組成

Abstract

<p>We conducted geochemical analyses of whole-rock major and trace elements including rare earth elements, and Sr-Nd isotopic compositions for the melanocratic porphyritic facies of the Yusubaru Granite. The facies were found by Yuhara et al. (2022), and were composed of hornblende - biotite granodiorite to granite. The facies are distributed at the boundary of the Aka body of the Asakura Granodiorite and the Yusubaru Granite, and are scattered in the Yusubaru Granite. Mineral textures of the melanocratic porphyritic facies indicate magma mixing. Whole-rock chemical variations and modal compositions of the melanocratic porphyritic facies are between the main facies and Aka body of the Asakura Granodiorite. U-Pb zircon dating separated from the Aka body of the Asakura Granodiorite gives an age of 98.7±0.6 Ma, which is considered to be a timing of the activity of this body, and the same timing of the Yusubaru Granite. The melanocratic porphyritic facies of the Yusubaru Granite was formed by mixing of the Yusubaru Granite magma and granodioritic magma, similar to the Aka body of the Asakura Granodiorite. </p>

Journal

  • Earth Science (Chikyu Kagaku)

    Earth Science (Chikyu Kagaku) 77 (4), 147-163, 2023-10-25

    The Association for the Geological Collaboration in Japan

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