1987 Volume 37 Issue 204 Pages 259-266
Homogenization temperatures and salinities of fluid inclusions in quartz, scheelite, clinopyroxene, and garnet from the Akemidani and Gosento ore bodies of the Fujigatani deposit and the Suo ore body of the Kuga deposit are measured in order to compare the formation temperatures of anhydrous skarns, quartz veins, and scheelite.
Homogenization temperatures and salinities of primary fluid inclusions in vein quartz from the Fujigatani deposit range from 361°to 191°C and 14 to 1 wt% (NaCl eq.), respectively. Primary fluid inclusions in scheelite show the homogenization temperatures ranging from 308° to 233°C, and the salinities ranging from 9 to 1 wt% (NaCl eq.), respectively. Homogenization temperatures and salinities of primary fluid inclusions in clinopyroxene range from 361°to 251°C and 11 to 3 wt% (NaCl eq.), respectively.
Primary fluid inclusions in vein quartz from the Kuga deposit show the homogenization temperatures ranging from 373°to 196°C, and the salinities ranging from 12 to 2 wt% (NaCl eq.), respectively. Homogenization temperatures and salinities of primary fluid inclusions in scheelite range from 376°to 242°C and 9 to 1 wt% (NaCl eq.), respectively. Homogenization temperatures of primary fluid inclusions in clinopyroxene and garnet range from 370°to 263°C and from 339°C to 275°C, respectively. Salinities of primary fluid inclusions in these minerals range from 11 to 2 wt% (NaCl eq.).
It is indicated for both deposits that the formation of quartz veins occurred at lower temperatures than that of skarns. Skarn scheelite precipitated at lower temperatures than clinopyroxene and/or garnet, whereas vein scheelite precipitated at higher temperatures than vein quartz. The temporal relationship between quartz veins and skarns, tex-tural relations of scheelite and other skarn minerals, and the fluid inclusion data suggest that the precipitation of scheelites occurred at the late stage of the formation of skarns, and at the early stage of the formation of quartz veins.
Difference in salinity of inclusion fluid is not observed between scheelites in skarns and in quartz veins. Homogenization temperature data show that vein scheelite from the Fujigatani deposit was formed at higher temperatures than skarn scheelite. On the other hand, vein scheelite from the Kuga deposit was formed at the same temperature with skarn scheelite. There is a possibility that the temperatures of hydrothermal solutions for these deposits die not decrease monotously, but fluctuated during the course of the mineralization of the Fujigatani deposit.
No apparent difference in formation temperature is observed between molybdenite and scheelite in quartz veins of the Fujigatani deposit.
