新第三紀熱水活動によって形成された愛媛県西条市・市之川角礫岩における砒素およびアンチモンの挙動  [in Japanese] Behavior of arsenic and antimony in Ichinokawa breccia formed by Miocene hydrothermal activities, Saijo City, Ehime Prefecture, Japan.  [in Japanese]

Access this Article

Search this Article

Author(s)

Abstract

In this paper, formation process of Ichinokawa breccia and antimony-arsenic mineralization in the breccia in the Ichinokawa area of Saijyo City, Ehime Prefecture, Japan, has been studied on the basis of geological, petrological and geochemical data. We have focussed on "hydraulic fracturing" process for the genesis of the Ichinokawa conglomerate. Ichinokawa conglomerate can be divided mainly into Ichinokawa breccia and Myojin Group. Carbonate-rich breccia and sandstone filling fractures are also found in the Sanbagawa schists adjacent to the Ichinokawa breccia. High-angle breccia zones, the Ichinokawa breccia, cut across the Sanbagawa schistocity. The Ichinokawa breccia consist principally of breccias which have been partly altered and veined by quartz, carbonate minerals and pyrite, and matrix of carbonate-rich sandstone. Schist clasts (up to 10 m across) in the breccia are angular but not variably rotated. Breccias are both clast- and matrix-supported and show evidence for single fracturing and healing by hydrothermally precipitated minerals such as carbonate minerals, pyrite, stibnite, pyrite and quartz. Two Sb and As-rich zones in the Ichinokawa breccia along the Ichinokawa River are about 10-30 m wide adjacent to the Sanbagawa schists. As and Sb values of carbonate matrix in the breccia are extremely high. These observations suggest that the the Ichinokawa breccia formed through a hydrofracturing process associated with hydrothermal fluid infiltrated into Sanbagawa metamorphic as precursor of the antimony ore forming. Hydrothernal fluid seems to have caused mineralization of carbonate minerals and sulfide minerals. Afterwards, the Myojin Group was accumulated above on the Ichinokawa breccia.

In this paper, formation process of Ichinokawa breccia and antimony-arsenic mineralization in the breccia in the Ichinokawa area of Saijyo City, Ehime Prefecture, Japan, has been studied on the basis of geological, petrological and geochemical data. We have focussed on "hydraulic fracturing" process for the genesis of the Ichinokawa conglomerate. Ichinokawa conglomerate can be divided mainly into Ichinokawa breccia and Myojin Group. Carbonate-rich breccia and sandstone filling fractures are also found in the Sanbagawa schists adjacent to the Ichinokawa breccia. High-angle breccia zones, the Ichinokawa breccia, cut across the Sanbagawa schistocity. The Ichinokawa breccia consist principally of breccias which have been partly altered and veined by quartz, carbonate minerals and pyrite, and matrix of carbonate-rich sandstone. Schist clasts (up to 10 m across) in the breccia are angular but not variably rotated. Breccias are both clast- and matrix-supported and show evidence for single fracturing and healing by hydrothermally precipitated minerals such as carbonate minerals, pyrite, stibnite, pyrite and quartz. Two Sb and As-rich zones in the Ichinokawa breccia along the Ichinokawa River are about 10-30 m wide adjacent to the Sanbagawa schists. As and Sb values of carbonate matrix in the breccia are extremely high. These observations suggest that the the Ichinokawa breccia formed through a hydrofracturing process associated with hydrothermal fluid infiltrated into Sanbagawa metamorphic as precursor of the antimony ore forming. Hydrothernal fluid seems to have caused mineralization of carbonate minerals and sulfide minerals. Afterwards, the Myojin Group was accumulated above on the Ichinokawa breccia.

Journal

  • Memoirs of the Faculty of Science,Ehime University

    Memoirs of the Faculty of Science,Ehime University 11, 65-80, 2005

    Ehime University

Codes

  • NII Article ID (NAID)
    110004715628
  • 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
    7731687
  • 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 
Page Top