愛媛県砥部町の万年変質安山岩体のボーリングコアにおける硫化鉱物の産状および砥素濃度

概要

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Mode of occurrences of sulfide minerals and As concentrations of samples from a horizontal boring core of Mannen altered andesite in the Tobe Town, Ehime Prefecture, Japan, has been investigated based on petrography, mineralogy and geochemistry. The Mannen altered andesite intrudes into the vicinity of boundary between the Sanbagawa metamorphic rocks and the Middle Miocene Kuma group. The andesite body has undergone extensive hydrothermal alteration, and has domains of a high concentration of As, S and Sb. Index alteration minerals are pyrite, arsenopyrite, marcasite, stibnite, quartz, opal, carbonate minerals, chlorite, illite and kaolinite. In the Mannen arrear textures of sulphide minerals can be divided into the following six types; sparse, sand spot pool and vein, and black-ink-drawing types. The black-ink-drawing type is characterized by the abundance in marcasite and arsenopyrite. The high concentration domains in arsenic are in general agreement with that characterzed by sulphide minerals of the black-ink-drawing type. Sb, S and As are extremely added and Na_2O, MgO, CaO and FeO are depleted in the Mannen andesites during the hydrothermal alteration on the basis of isocon analyses.
愛媛大学の論文
2005-03-25