Study on the Features of Ore-Forming Fluid of Dafulou Sn–Polymetallic Deposit (Guangxi, P. R. China)

For a long time, there are some debates about the genesis of the Dachang Sn-polymetallic ore deposit. The core issues consist of the ore-forming fluid, the mineralization age, etc. In order to clear the fluid problem, the fluid inclusion was studied by determining the component, the temperature and the pressure, etc. As a result, on the basis of the optical observations and the micro-thermometric data, the fluid inclusions were divided into six types. It is suggested that the different minerals have different homogenization temperature and salinity. For example the quartz and calcite, their average homogenization temperature is 240 to 420°C, 120 to 145°C, their average salinity is 17 to 30% NaCl, 17.3 to 17.6wt% NaCl. In the whole, the quartz has higher homogenization temperature and salinity than calcite. The forming pressure of fluid inclusion is about 120 to 650×105Pa, and the inferred depth of mineral forming is about 0.4 to 2.6 km.