Fahlore and Sphalerite from the Darasun Gold Deposit in the Eastern Transbaikal Region, Russia: II. Fe and Zn Partitioning, Fluid Inclusions, and Formation Conditions

The partitioning of Fe and Zn between coexisting fahlore and sphalerite and fluid inclusions in sphalerite from the Darasun gold deposit have been studied. These data were used to estimate the formation temperature of the minerals by the sphalerite–fahlore geothermometer. The calculated crystallization temperature of 175–355°С is close to the homogenization temperature of fluid inclusions in sphalerite of 225–385°С.The estimated pressure for fluid inclusion trapping ranged from 340 to 1420 bar. The sulfur fugacity obtained from the FeS content in sphalerite associated with pyrite and the calculated temperature ranges from 10–5.5 to 10–11 bar.