Xenothermal-type deposits

In contrast, in Southwest Japan, polymetallic veins (so-called xenothermal-type deposits in the sense of Buddington (1935) or subvolcanie hydrothermal type in the sense of Cissartz (1928, 1965) and Schneiderhohn (1941, 1955) occur. Examples of these deposits are Ashio, Tsugu, Kishu and Obira. All these vein-type deposits have formed at middle Miocene age in western part of Tanakura Tectonic Line under subaerial environment. In these deposits, many base-metal elements (Sn, W, Cu, Pb, Zn) and small amounts of Au and Ag are concentrated. These deposits are associated with felsic volcanic and plutonic rocks along the Median Tectonic Line (MTL) or south of MTL. 

During the Miocene age, polymetallic vein-type (xenothermal-type, subvolcanic-type) and gold-quartz vein-type (mesothermal-hypothermal-type) mineralizations occurred mainly in middle to western part of Japan. They are described in section 1.6.1. In section 1.6.2, Hg and Sb vein-type deposits are described. 

The other important deposit types of the Neogene age are polymetallic (Cu, Pb, Zn, Sn, W, Au, Ag) (xenothermal or subvolcanic type deposits) vein-type deposits, hypo/mesothermal Au vein-type deposits, disseminated-type (hot spring type) Au deposits, and Hg-Sb disseminated and vein-type deposits. 

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See also in sourсe #XX -- [ ]

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