Geothermal field of ore-forming fluids of antimony deposits in Xikuangshan
YANG Rui-yan, MA Dong-sheng, PAN Jia-yong (State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China)
A hydrothermal convection model according to the geohydrologic condition of the Central Hunan Basin is established. The Longshan Xikuangshan section is selected to numerically simulate the geothermal field of fluids during ore forming periods of the antimony deposits in Xikuangshan on different hypotheses. Combining with the results of fluid inclusions, the ore forming pattern of the antimony deposits in Xikuangshan is established. The main ore forming fluid of the antimony deposits in Xikuangshan originated from meteoric water at the edge of the basin. Being continually heated and leaching out antimony components of the strata during their movement, the fluids carried them to Devonian limestones forming the antimony deposits. The simulation results show that there lies a concealed rock mass under Xikuangshan, and the heat flow of the mass is 0.2 W/m2. The geothermal gradient during the ore forming periods in Xikuangshan is approximately 86 ℃/km, the temperature of the paleofluid at ore forming position is about 180～200 ℃, the density of the paleofluid is 865～887 kg/m3, and the velocity of the paleofluid near the ore body approaches 0.5 m/a.