The Research Of Mineral Fluid And Metallogenic Mechanism In JinChangYu Gold Deposit

To make up for the lacking of system research of gold ore-forming fluid,The author collected the inclusions in the samples of four metallogenic period on the basis of field investigation work. The research includes petrography observation? temperature testing?physical parameter estimating?component testing of Laser Raman and Group inclusions?Hydrogen-oxygen and Sulfur isotope studies.The author found that the property of gold ore-forming fluid of JinChang-yu gold deposit is weak acid, less-oxidation and medium-low temperature.Ore-forming fluid inclusions'types are NaCl-H2O inclusions?NaCl-H2O-CO2 inclusions?pure gas phase and liquid phase inclusions, and the main type is NaCl-HaO inclusions.The changement of ore-forming fluid Nature is large.In prior to the mineralization the ore-forming fluid is NaCl-H20 system,which contains CO2?Ca+?K+?Na+?SO42-?Cl-?the temperature is medium-high,and the NaCl salinity is low.When the fluid evoluted to the main metallogenic period, the ore-forming fluid is NaCl-H20 system,which include lots of pure gas and liquid phase inclusions, the temperature decreases to medium-low, the content of CO2 and CH4 reduced and the content of O2 increased, the value of pH becomes more neutral.The fluid experienced a boiling and an immiscible process at the same time.In the late mineralization the temperature and NaCl salinity of ore-forming fluid becomed lower and the carbon content chenged Lower,but the system is still NaCl-H2O.Some of the liquid phase composition(such as Ca2+, Na+, K+, SO42-, Cl") control the mineralization,Gold element move in the form of complex migration-K+/Na+(AuClx)-;The study of sulfur isotope in the main mineralizing stage reveals that ore-forming materials may mainly come from the deep magma and the sulfur element have characteristics of originating from the mantle.The study of hydrogen and oxygen stable isotope indicates that in stage I the mineralizing fluids were mainly magmatic water, but during stage II the mineralizing fluids were mixed with precipitation.The boiling of the fluid which caused by severe pressure releaseing and the mixing of the precipitation and magmatic fluid are the main mechanisms of mineralization. The prospective reserves in the deep and around the original ore body are very well from the views of 4 to 8 km's estimating value of ore-forming depth.