Polymetallic vein

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. 

Polymetallic vein-type deposits occur in middle Miocene volcanic terrain in central and western Japan. 

Figure 1.124. Ag/Au total production ratio from each mine and Ag content of electrum. Solid circle epithermal Au-Ag vein-type deposits. Open circle epithermal base metal vein-type deposits. Solid square hypo/mesothermal polymetallic vein-type deposits. Open. square epithermal Au disseminated-type deposits. I Tada, 2 Toyoha, 3 Omidani, 4 Innai, 5 Ikuno, Oe-Inakuraishi, 7 Nebazawa, 8 Kawazu, 9 Todoroki, 10 Yatani, 11 Seigoshi, 12 Sado, 13 Takeno, 14 , awaji, 15 Yugashima, 16 Takadama, 17 Handa, 18 Konomai, 19 Sakoshi-Odomari, 20 Toi, 21 Sanru, 22 Arakawa, 23 Taio, 24 Chitose, 25 Hokuryu, 26 Okuchi, 27 Fuke, 28 Yamagano, 29 Akeshi, 30 Kasuga (Shikazono, 1986).

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. 

This spatial difference is consistent with the distribution with that of hydrothermal deposits of middle Miocene (Kuroko and polymetallic vein-type deposits in Japan). 

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. 

The relationship between the iron content of stannite in equilibrium with sphalerite and pyrite or with sphalerite and pyrrhotite was derived based on thermochemical data by Scott and Barnes (1971), Barton and Skinner (1979) and Nakamura and Shima (1982). These types of deposits are skam-type polymetallic (Sn, W, Cu, Zn, Pb, Au, Ag) vein-type and Sn-W vein-type deposits. As shown in Fig. 1.181, the /s -temperature range for each type of deposits is different at a given temperature, /sj increases from Sn-W vein-type through skam-type to polymetallic vein-type deposits. It is interesting to note... 

Figure 1.185. Locations of hypo/mesothermal vein-type deposits in Japan. Abbreviations are the same as those in Fig. 1.62. Open circle hypo/mesothermal Au vein-type deposits. Solid circle hypo/mesothermal polymetallic vein-type deposits (Shikazono and Shimizu, 1988a).

Nakamura, T. (1970) Mineral zoning and characteristic minerals in the polymetallic veins of the Ashio copper mine. In Tatsumi, T. (ed.), Volcanism and Ore Genesis. Tokyo U. Tokyo Press, pp. 231-246. 

Sawai, O. (1999) Wall rock alteration of the Toyoha polymetallic vein-type deposits,. southwestern Hokkaido, Japan. Resource Geology Special Issue, 20, 99-112. 

As noted already, the formation of polymetallic vein-type deposits and Kuroko deposits occurred under the subaerial and submarine environments, respectively, at nearly the same time (middle Miocene). 

During the middle Miocene, Kuroko deposits, polymetallic vein-type deposits, gold-quartz vein-type deposits and Sb and Hg vein-type deposits were formed (see sections 1.3 and 1.6). Many vein-type deposits were formed not only in and nearby the Japanese Islands, but also at middle Miocene in northwest USA (Basin and Range Lipman, 1982), and elsewhere in the circum-Pacific regions (e.g., Peru). It is probable that large amounts of CO2 effused into the atmosphere from hydrothermal solution associated with this widespread mineralization and volcanic gas from subduction zones, causing an increase in temperature. 

For instance, polymetallic vein-type deposits formed under the subaerial environment influenced by igneous and sedimentary components. 

Metals distribution and correlations in polymetallic veins from Pingiiino indium-bearing deposit, Deseado Massif, Patagonia, Argentina... 

The polymetallic veins are poorly exposed at surface and are characterized by the presence of gossans with remnants of breccias with quartz matrix and oxidized sulfide clasts. Hypogene polymetallic mineralization is characterized by the presence of massive and banded sulfide veins and sulfide breccias up to 13 m thick. This mineralization is developed In... 

Indium concentrations in the polymetallic veins show a wide range (3.4 to 1184ppm In, Table 1). Based on the correlation coefficients of ore geochemistry, significant Indium (up to 1184 ppm) is related to the Ps2 mineralization stage and closely associated with Fe-rich sphalerite, but also with ferrokesterite. There are important In anomalies in Psi (up to 159.4 ppm) that are related to the Sn minerals, cassiterite, ferrokesterite and stannite (Crespi 2006). 

The granitic rocks of the NPSG are the youngest granitic rocks in the Long Lake area and are associated with several styles of mineralization an early base metal (Zn, Cu, Pb) and granophile element (Mo, Sn, W, In) polymetallic vein system is associated with the emplacement of the NPSG (Fyffe Pronk 1985), and later uranium vein mineralization, that resulted from... 

Kooiman, G.J.A., McLeod, M.J., Sinclair, W.D. 1986. Porphyry Tungsten-Molybdenum Orebodies, Polymetallic Veins and Replacement Bodies, and Tin-Bearing Greisen Zones in the Fire Tower Zone, Mount Pleasant, New Brunswick. Economic Geology, 81, 1356-1373. 

Novak and Valcha (1964) in drusy cavities of hydrothermal polymetallic veins as the latest mineral, Hora Svate Katering in the Krusne Hory Mountains, Czechoslovakia. 

Monohydrocalcite from polymetallic vein of the Vrandice deposit, near Pfibram, Czechoslovakia. 1789 ... 

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