Fluid Inclusions Study And Its Genesis Of Erze Glod-deposit,Muli SiChuan

The Erze gold-deposit is located in the southeastern margin of the Songpan-Ganzi belt,and is adjacent to Yanyuan-Lijiang belt in the Yangzi composite platform,In the region,there are two main stratums of exposing:the marine stratum of preSinian to Triassic and the continental strataum of after the third century.The ore bodies mainly occur in the giant thick carbonate rock series in the upper Permian.The size of the ore body is different, the difference is quite great, the size of the ore body is related to the structural position of the ore body and the nature of the ore-controlling structure.On the basis of previous studies,through the observation of petrography for fluid inclusions, Micro temperature measurement and thermodynamic calculation and so on,the physicochemical properties of metallogenic fluid of the Erze gold-deposit, metallogenic material source and metallogenic epoch and migration and deposit of metallogenic elements and some knowledge was obtained:The inclusion in the the Erze gold-deposit are mainly H2 O inclusions, H2O-CO2 inclusions and pure CO2 inclusions.It is showed that the temperature ranges of H2 O inclusions by measuring temperature is about 124.6~316.2?, the average temperature is 193.5?, salinity ranged from 3.06~5.86(wt%NaCl),and the average is about4.74(wt%NaCl);the temperature ranges of H2O-CO2 inclusions between 179.6~296?,and the average value is about 245.4?, salinity varies mainly in1.83~3.57(wt%NaCl),and the average is 2.41(wt%NaCl).The density variation range of the fluid is 0.93~0.97g/cm3, the average value is 0.93g/cm3,so we can know that the metallogenic fluid of the Erze gold-deposit is a high density fluid.Capture pressure ranges from1010 bar,therefore,The metallogenic depth of Erze gold-depositis is about3.86 km.According to the Rb — Sr isotope method of measuring the age values for136.75-139.70 Ma,so we consider that the metallogenic age of the Erze gold deposit is early Cretaceous.The characteristics of the hydrogen and oxygen isotopes indicate that ore-forming fluid is the main soure of atmospheric precipitation recharge.The Au(HS)2- as main migration form of Au in the Erze gold deposit,and the second is Au2(HS)2S2-.Due to the infiltration of precipitation and the influence of crustal movement, the ore-forming fluid composition and the pressure of the ore-formingfluid had been changed,so that the liquid immiscibility had happened,resulting in Au in favorable part of the precipitation of gold deposits.