Compositional Characteristics of Ores and Rare Minerals in the Kieslager-type Deposits of Japan

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The Kieslager-type deposits are genetically related with submarine basic volcanism. The ores are mineralogically very simple consisting mainly of pyrite, chalcopyrite and sphalerite. Galena, tetratedrite and native gold occur rarely in copper-rich ores, and several kinds of cobalt minerals in pyrrhotite-rich ores converted from pyritic ores.Colusite with up to 4.3 % germanium occurs with bornite, chalcopyrite, pyrite and barite in Zn-rich ores of the Hinotani L-1 orebody, Yanahara mine. The occurrence of Ge-bearing minerals has been known in the Kuroko deposits related genetically with acidic volcanism, but not known in the Kieslagertype deposits. The rhyolitic volcanism in near-continent submarine environments is suggested to be responsible for the ore genesis at Yanahara.The ^<34>S values(CDT)of sulfide minerals including the present data are in a narrow range from +1 to +7 % in the Kieslager-type deposits, similarly to the modern Ridge sulfide deposits. The values seem to be larger in the deposits of the Shimanto belt and of the Tenryu river area in the Sanbagawa belt, compared with the deposits in the Sanbagawa belt in Shikoku. The reason is remained unsolved. Further isotopic study is needed.