Characteristics of Ore-forming Fluid of Gold Deposit in Laozhaiwan,Yunnan Province

The Laozhaiwan gold deposit of Yunnan,located in triangular metallogenic region of Yunnan,Guizhou,Guangxi Provinces,is fine-grained gold deposit in low grade but great reserves,ore-bearing stratum is fine-grained clastic rock of lower series of Upper Devonian in Caledonian paleo-uplift zone.Through the primarily study on compositions,densities,pressures,depth and sulfur,hydrogen and oxygen isotopes of hydrothermal ore-forming fluid inclusions of gold deposit in Laozhaiwan,the authors conclude that ore-forming fluid is in low-medium temperature(110～253 ℃),low salinity(23.86～11.2 Wt% NaCl)and low density(0.97～1.08 g/cm3)which belongs to(SO2-4)Cl--(K+)Na+ hydrochemical type in a shallow(0.21～1.14 km)environment.The ore-forming fluid mostly derived from products by exchange of mantle differentiation fluids and meteoric water,surface water.Laozhaiwan gold deposit is a hydrothermal deposit in low-medium temperature and low salinity.