Characteristics of fluid inclusions in the Tiemurte Pb-Zn deposit,Altay,Xinjiang and its geological significance

The Tiemurte middle-size lead-zinc deposit occurs in Kelang basin on the southern margin of Altay and it is an important VMS style. The Tiemurte deposit occurs in second lithological unit of Upper Silurian-Lower Devonian Kangbutiebao Formation,with the host rocks being marble,greenschist,meta-calcareous siltstone and skarn. The ore bodies show bed-like or lenticular. The lead-zinc deposit is subjected to three stages:Sedimentary exhalative stage,superposed rebuilding stage and hypergenesis stage. The inclusions in quartz,feldspar,calcite and garnet are dominantly liquid inclusions type. In addition,the inclusions in quartz including rich gas phase inclusions,single gas inclusions,daughter mineral-bearing inclusions,CO2-bearing three-phase and aqueous two-phase. In sedimentary exhalative stage,homogenization temperatures of inclusions vary from 150℃ to 330℃ with peak temperature of 165℃ and 285℃,the salinity from 4% to 16% NaCl equiv,the density ranges from 0.77g/cm3 to 0.97g/cm3,the cations in inclusions are dominanted by Na+ and K+,the anions are Cl-and SO42-and the gases in fluid inclusions are chiefly composed of H2O and CO2. In superposed rebuilding stage,homogenization temperatures are 150~480℃,the salinity is 2.2% to 17.08% NaCl equiv and 33.93% to 47.2% NaCl equiv,the density ranges from 0.61g/cm3 to 1.03g/cm3,the cations in inclusions are Na+ and K+,the anions are Cl-and SO42-and the gases in fluid inclusions are chiefly composed of H2O and CO2,the secondary components are N2,CH4.