Research On Geological Features, Fluid Inclusion And Genesis Of Woxi Au-Sb-W Deposit In Hunan Province

The paper aims to summary the forming cause of Woxi Au-Sb-W deposit by means of mineralogical study of fluid inclusions, combined with the analysis of deposits in the geological characteristics and Metallogenic geological conditions. The main contents and opinions are described as follows:(1) Reviews on the topic of the fluid inclusion analysis, and introducing the previous work on deposits.(2) Through observation and study of the geological features, discussed the mine stratigraphy, tectonic, magmatite, orebodies, ore and wall rock alterations of the deposit.(3) Veins are divided into interlaminar veins, stockwork veins and joint veins owning to there output form. Through mineral paragenesis assemblages designated as seven kinds of ore types;Divided deposition enrichment and hydrothermal mineralization of two ore-forming period, and the period of which hydrothermal mineralization can be divided into4stage by the mutual relationship of ore texture and structure, mineral paragenesis assemblages.(4) By the testing and analysis of the inclusions, obtained Au-Sb-W ore formation temperature in the range of147～288℃,the mineralization process has been repeated severel times. Most of the salinity of the ore-forming fluids concentrated in the4.0～8.0wt%NaCl, which is close to salinity of underground water. So we conclude that it’s metamorphic fluid of low salinity. Ore-forming fluid density range from0.54to0.98g/cm3, average is0.86g/cm3which belongs to a low-medium density fluid. Ore-forming fluids is water-based, the liquid phase is mostly composited of Ca2+, Na+, K+, SO42-, Cl-, F-; Gas phase composition other than water, dominated by CO2, and a certain amount of CO and CH4, ect. Ore-forming solution is H2O-Na+(Ca2+、K+)-Cl-(SO42-、F-)-CO2System.(5) Summarizing the favorable mineralization conditions of deposit from geological setting, host strata, ore-control structures, ore-bearing magmatic rocks, alteration and mineralization features. It is reached that the Madiyi strata with higher Au, Sb, W background values turn out to be Source bed, which provide the sources of ore deposits;No magmatic rocks within the mining area;The main wall-rock alteration (bleaching, pyritization, silicification) is spatially related to the mineralization, especially the identification of bleaching and pyritization can be directly recognized as a mining area prospecting.(6)Above all, it is confirmed that the genesis type of the deposit is medium-low temperature metamorphic superimposed stratabound hydrothermal quartz vein-type deposits.