愛媛県砥部町の万年変質安山岩体の化学的風化における主要・微量元素の挙動  [in Japanese] Behavior of major and trace elements of the Mannen altered andesite during chemical weathering in the Tobe Town, Ehime Prefecture, Japan  [in Japanese]

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Abstract

The weathering process of Mannen altered andesite in Tobe Town, Ehime Prefecture, Japan, has been investigated based on geology, petrography and geochemistry. The Mannen andesite intrudes into the Sanbagawa metamorphic rocks and the Middle Miocene Kuma group. The andesite dyke have undergone extensive hydrothermal alteration and mineralization, and has domains of a high concentration of As, S and Sb. Index alteration minerals are pyrite, arsenopyrite, marcasite, stibnite, quartz, carbonate, chlorite, titanite and illite. The weathering types in the near surface of the Mannen andesite is divided into five based on the degree of progress of weathering. That results show that domains of sulphide minerals-rich altered andesite are extremely weathered. CaO, Fe_2O_3, MgO, Pb, Cu, Sb, S and As are depleted in weathered parts of the Mannen andesite based on isocon analysis. Especially, Fe_2O_3, S and As are extremely depleted in weathered parts of sulphide minerals-rich altered andesites. It shows that sulphide minerals in the andesite are decomposed by interaction of surface water and microbial activity, and these elements are leaching away to surrounding environments.

The weathering process of Mannen altered andesite in Tobe Town, Ehime Prefecture, Japan, has been investigated based on geology, petrography and geochemistry. The Mannen andesite intrudes into the Sanbagawa metamorphic rocks and the Middle Miocene Kuma group. The andesite dyke have undergone extensive hydrothermal alteration and mineralization, and has domains of a high concentration of As, S and Sb. Index alteration minerals are pyrite, arsenopyrite, marcasite, stibnite, quartz, carbonate, chlorite, titanite and illite. The weathering types in the near surface of the Mannen andesite is divided into five based on the degree of progress of weathering. That results show that domains of sulphide minerals-rich altered andesite are extremely weathered. CaO, Fe_2O_3, MgO, Pb, Cu, Sb, S and As are depleted in weathered parts of the Mannen andesite based on isocon analysis. Especially, Fe_2O_3, S and As are extremely depleted in weathered parts of sulphide minerals-rich altered andesites. It shows that sulphide minerals in the andesite are decomposed by interaction of surface water and microbial activity, and these elements are leaching away to surrounding environments.

Journal

  • Memoirs of the Faculty of Science,Ehime University

    Memoirs of the Faculty of Science,Ehime University 11, 39-46, 2005

    Ehime University

Codes

  • NII Article ID (NAID)
    110004715625
  • NII NACSIS-CAT ID (NCID)
    AN10408332
  • Text Lang
    JPN
  • Article Type
    Departmental Bulletin Paper
  • Journal Type
    大学紀要
  • ISSN
    09195203
  • NDL Article ID
    7731659
  • NDL Source Classification
    ZM2(科学技術--科学技術一般--大学・研究所・学会紀要)
  • NDL Call No.
    Z14-2057
  • Data Source
    NDL  NII-ELS  IR 
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