FLUID INCLUSION IN THE HULALIN GOLD DEPOSIT, INNER MONGOLIA

On the basis of the results from the inclusion petrofacies, micro-thermometry and laser Raman spectrographic analysis, the ore-forming fluid characters are systematically studied, and the genesis of the Hulalin gold deposit is discussed. The results show that these inclusions consist of mainly gas-liquid two-phase, with minor CO₂-bearing three-phase, daughter mineral-bearing three-phase and pure CO₂ types. The homogenization temperature of ore-forming fluids ranges from 320 to 360℃, with salinity (NaCl) of 19.2%-21.8%, and density of 0.73-0.90 g/cm³. The estimated mineralizing pressure is between 92.1 and 129.1 MPa, with mineralizing depth of 3.07-4.3 km. The gas composition of ore-forming fluids is mainly H₂O, followed by CO₂, CH₄ and N₂, with less C₆H₆, C₂H₆ and C₃H₈, belonging to H₂O-CO₂-NaCl system. The ore-forming fluids are unmixed, mainly from the deep magmas and maybe joined with mantle components. The gold is transferred mainly in the form of gold-chlorine complex. The geological and geochemical features of the deposit are similar to those of cryptoexplosion breccia gold deposits. So it can be assigned to the cryptoexplosion breccia type.