1989 Volume 39 Issue 213 Pages 33-44
Homogenization temperatures and salinities of fluid inclusions in some minerals from the Kawahira and Seikyu deposits in Shimane Prefecture, Shisou deposit in Hyogo Prefecture, and Nakatatsu deposit in Fukui Prefecture were measured in order to evaluate physico-chemical conditions for the molybdenum mineralization, and to compare them with those for tungsten and other metalliferous deposits in Japan.
Salt-bearing polyphase inclusions as well as liquid-rich two-phase inclusions are found in vein quartz from the Kawahira deposit, in pegmatitic quartz from the Shisou deposit, and in clinopyroxene from the Nakatatsu deposit. CO2-bearing fluid inclusions as well as liquid-rich two-phase inclusions are found in vein quartz from the Seikyu deposit.
Fluid inclusions in vein quartz from the Kawahira deposit show the homogenization temperatures ranging from 215°to 390°C, and the salinities ranging from 3 to 37 wt% (NaCl eq.). Plots of homogenization temperature against salinity of fluid inclusions show two populations of inclusions. It is concluded that these two populations originated from incomplete mixing of saline solution with dilute one.
Homogenization temperatures and salinities of fluid inclusions from the Seikyu deposit range from 191°to 325°C, and from 4 to 18 wt% (NaCl eq.), respectively.
Data for the Shisou deposit show that the homogenization temperatures range from 205°to 416°, and that salinities range from 11 to 44 wt% (NaCl eq.).
Fluid inclusions in clinopyroxene, vein quartz, and calcite from the Sennou ore body of the Nakatatsu deposit show the homogenization temperatures ranging from 342°to 520°C, from 170°to 467°, and from 140°to 397°, respectively. Salinities of fluid inclusions in clinopyroxene, vein quartz, and calcite range from 2 to 50 wt% (NaCl eq.), from 1 to 15 wt% (NaCl eq.), and from 0 to 11 wt% (NaCl eq.), respectively. It is shown that clinopyroxene precipitated at higher temperatures than quartz and calcite in veins. Plots of homogenization temperature against salinity of fluid inclusions show two populations of inclusions; one for the mineralization of clinopyroxene with large variation in salinity, and the other for the mineralization of quartz and calcite with large variation in temperature.
Compilation of fluid inclusion data for Japanese molybdenum deposits shows that the hydrothermal solutions with high salinities are characteristic for molybdenum mineralization in Japan, compared with Japanese tungsten and other metalliferous deposits.
