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Mineralogical and Genetical Aspects of the Doyashiki Kuroko Deposits, Hokuroku Basin, Japan
Author(s) -
Kitazono Satoshi,
Ueno Hirotomo
Publication year - 2003
Publication title -
resource geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 43
eISSN - 1751-3928
pISSN - 1344-1698
DOI - 10.1111/j.1751-3928.2003.tb00165.x
Subject(s) - bornite , sphalerite , chalcopyrite , pyrite , geology , marcasite , geochemistry , galena , tetrahedrite , covellite , gangue , sulfide minerals , mineralogy , volcanogenic massive sulfide ore deposit , mineralization (soil science) , chalcocite , sulfur , metallurgy , materials science , copper , soil science , soil water
. A detail investigation of ore and gangue minerals was performed on the Doyashiki Kuroko deposits, Hokuroku basin, Japan for the first time. Main ore minerals are sphalerite, galena, pyrite, chalcopyrite, tetrahedrite‐tennantite and digen‐ite. Small amounts of enargite, wittichenite, electrum, covellite, bornite, marcasite and hematite are also observed. Quartz, barite and gypsum are common gangue minerals. Homogenization temperatures and salinities of fluid inclusions in quartz, sphalerite and barite range from 190 to 240d̀C and 3.0 to 5.5 wt% NaCl equivalent, respectively. The FeS contents of sphalerite and Ag contents of electrum were 0.12 to 0.18 mol %, 39.0 to 39.6 atom %, respectively. The chemical composition of digenite as a primary mineral shows high sulfur contents. These data indicate that ore fluid responsible for digenite and associated ore minerals was characterized by a range of high sulfur fugacity with a moderate formation temperature. This is concordant with the mineral assemblage of bornite‐pyrite and chalcopyrite, which shows high sulfur fugacity conditions. It seems that the mineralization closely associated with acidic volcanism has occurred around 13 Ma of Middle Miocene on the seafloor at the depth of about 1500 m.