The Characteristics Of Ore-Forming Fluids And Mineralization Genesis Of The Shuangjianzishan Pb-Zn-Ag Deposit In Inner Mongolia,China

The Shuangjianzishan Pb-Zn-Ag deposit is located in Fuhe town,Banner of Bahrain,which is a typical super-large hydrothermal vein-type deposit in the southern section of Da Hinggan Mountains.This deposit is rich in resources and there is a still huge ore-prospecting potential.This work combined systematic methods,including fluid inclusions,H-O and C-O isotopes,to discuss the origin of the ore fluids and the genesis of the deposit.The major conclusions achieved are as follows:?1?The ore-forming process can be divided into three stages including the early,major and late ore stages,which are quartz-pyrite stage,galena-sphalerite-silver mineral stage and quartz-calcite stage.?2?Through the micro-thermometry and laser Raman spectroscopic,the main types of fluid inclusions are composed of liquid-rich inclusions and vapor-rich inclusions.The liquid composition is dominated by H₂O.The gas composition of early stage inclusions is mainly CO₂,and the major and late stage inclusions contain CO₂ and CH₄.Homogeneous temperatures for different ore stages vary from 220 to 280?,200 to 250?and 160 to 240?,respectively.The fluid salinities vary from 1.05 to 8.14%and the densities range from 0.74to 0.92 g/cm³.The trapping pressures are from 35.05 to 80.29MPa,respectively,corresponding to the depths of 1.17 to 2.68km.The metallogenetic temperatures show a decreasing trend and salinities and densities are almost unchanged.This study shows that the ore-forming fluid is middle-low temperature,low salinity,low density,middle-low pressure and middle-low depth.?3?The H-O and C-O isotopic compositions show that the ore fluids are dominated by a mixture of magmatic fluid and meteoric water.The magmatic component is dominant in early stage fluid,whereas,the large involvement of meteoric water is dominant in the final stage fluid.