Kishu deposit

The Kishu deposit, located at middle Honshu, is associated with Kumano acidic rocks intruded into the Shimanto and Kumano formations. K-Ar age determination indicates that the activity of Kumano acidic rocks occurred at middle Miocene (14 1 

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Figure 1.18. Variation of Fe " /(Fe + Mg) and tetrahedral AI of chlorite from hydrothermal ore deposits Japanese Neogene Cu-Pb-Zn vein-type (open circle) and Kuroko deposits (solid circle). Localities 1 Ashio, 2 Yatani, 3 Toyoha, 4 Kishu, 5 Sayama, 6 Mikawa, 7 Furutobe, 8 Hanaoka, 9 Wanibuchi, 10 western Bergslagen (Shikazono and Kawahata, 1987).

Figure 1.83. Variation of Fe /(Fe + + Mg) and tetrahedral Al of chlorite from hydrothermal ore deposits Japanese Neogene Cu-Pb-Zn vein-type (open circle) and Kuroko deposits (solid circle). Localities 1 Ashio (Nakamura, 1960, 1963) 2 Yatani (Hattori, 1974) 3 Toyoha (Shikazono 1974a, Sawai, 1984) 4 Kishu (Shirozu, 1958) 5 Sayama (Shirozu, 1958) 6 Mikawa (Nagasawa, 1961) 7 Furutobe (Shirozu et al., 1975) 8 Hanaoka (Hayashi 1961, Hayashi and Oinuma, 1965 Tsuzuki and Honda, 1977 Shirozu et al., 1975) 9 Wanibuchi (Sakamoto and Sudo 1956, Iwao and Minato 1959, Katsumoto and Shirozu, 1973) 10 western Bergslagen (Baker et al., 1983) (Shikazono and Kawahata, 1987).

It is generally accepted that Kuroko deposits formed under the submarine environment, while polymetallic vein-type deposits in central and Northwest Japan (Ashio, Tsugu, Kishu, Obira, etc.) under the subaerial environment. 

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. 

Figure 1.170. Diagram showing the octahedral composition of chlorites from the subvolcanrc hydrothermal deposits, propylite, and Kuroko deposits in Japan (Nakamura, 1970). Chlorite occurring as a gangue mineral in the subvolcanic hydrothermal deposits Nos. 1, 2, 3 and 4 Chlorite from the Ashio copper mine. Nos. 5, 6, and 7 Chlorite from the Kishu mine. No. 8 Chlorite from the Arakawa mine. Nos. 9 and 10 Chlorite from the Ani mine. No. 11 Chlorite from the Osarizawa mine. Chlorite from the so-called propylite No. 12 Chlorite from the Yugashima mine. No. 13 Chlorite from the Budo mine. Chlorite from the Kuroko deposits No. 14 Chlorite from the Wanibuchi mine.

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