Fluid Inclusion Study of Skarns in the Maruyama Deposit, the Kamioka Mine, Central Japan

Abstract

Fluid inclusions in skarn minerals in the Maruyama deposit, the Kamioka mine, central Japan were studied. Homogenization temperatures (Th) of fluid inclusions in 48 skarn minerals (hedenbergite, andradite, epidote and quartz) were measured, and gas composition of fluid inclusions in 12 skarn minerals was measured with a quadrupole mass spectrometer. The maximum Th value of primary inclusions in hedenbergite is 380°C with peaks around 360°C. Primary inclusions in hedenbergite near contact between skarn and limestone have slightly lower Th values and their distribution has a tendency of long trail skirt toward low temperature, which indicates ceasing of skarnization coincides with temperature decrease. Fluid inclusions in andradite and quartz in the hedenbergite skarn have lower Th values, in this order, than those in hedenbergite. CH4-detected fluid inclusions are localized around the Maruyama fault. Gas composition of the fluid inclusions indicates that fluid trapped in the hedenbergite has CO2 content less than 1 mole % and is not in equilibrium with graphite.

Geology and Skarn Cu–Bi–Au Mineralization at Shwe Min Bon Area, Kalaw Township, Southern Shan State, Myanmar

“…Among the different types of skarn deposits, the Cu‐type skarn typically exhibits fluid inclusion homogenization temperatures ranging from 300 to 550 °C (e.g. Takeno et al, ). The temperature and salinity of fluid associated with the prograde skarn formation trapped in garnet were high temperature (314–492 °C) and hypersaline (up to 46.4 wt.% NaCl equiv.)…”