Geochemical Characteristics And Genesis Of The Sixteen Penggong Au-Sb-W Deposit In Woxi Hunan

Abstract:Sixteen penggong Au-Sb-W deposit located at the center of Woxi mining area, which is on the regional structure in xuefeng arc tectonic uplift belt in the north east, is an important ore deposit in xuefeng’s arc tectonic uplift gold-stibium-tungsten metallogenic belt. Based on the analysis of the Au-Sb-W deposit’s geological characteristics, geochemical characteristics, fluid inclusions characteristics and the ore-forming geological background, the author researches the sixteen penggong ore deposit on its source of ore-forming material, geochemical characteristics of the ore-forming fluid, the main ore-controlling factors, the genesis of deposit and etc. The main achievements and innovations are made as follows:1.The8Eu value of the mineral centering from0.60to0.73,with a weak negative Eu abnormality, reflects the low oxygen fugacity relative reduction of the metallogenic environment. Most of the δCe value is between0.93and0.99, with no apparent Ce abnormality. The δEu value of the altered surrounding rock and ore rock is between0.57and0.72, and the Ce value is between0.92and0.98, with no with no apparent Ce abnormality. No matter the ores, altered rock and near surrounding rock, their distribution pattern figure of rare earth elements is similar to the regional Ptin and Madiyi group slate, for they are both rightleaning, riched in light rare earth and having flat heavy rare earth. All above explains the rare earth’s component of hot resolution and that the metallogenic materials come from regional stratum.2.The research on deposit’s fluid inclusion in quartz shows that the main type of this deposit’s fluid conclusions is L-V rich fluid inclusions, and the characteristics of this inclusions reveals that the ore-forming fluid has characteristics such as meso-low temperature(180～220℃), low salinity(2～6wt%NaCl) and meso-low density. Meanwhile, in the evolution process of mineralization from early stage to late stage, similar to the underground hot water value,ore-forming temperature is gradually reduced and the salinity of the ore-forming fluid is gradually increased, which represents metallogenic mixing action has happened before. The analysis on the composition of the fluid inclusions show that the metallogenic solution belong to Na+(K+、Ca2+)-Cl--SO42-fluid.3.Through the evaluation, we can know that the range of metallogenic fluid for uniform pressure value is from6to21.04MPa, which is mainly centered from8to12MPa. And with this pressure value, we can calculate the ore-forming depth, which is about0.6-2.1Km.4. Combining this ore deposit’s source of ore-forming materials, the geochemical characteristics and functions of the ore-forming fluid, the analysis of the main ore-controlling factors and the ore-forming mechanism, we can conclude that the sixteen penggong Au-Sb-W deposit’s formation is not because of the magmatic hydrothermal, but Mainly in the low temperature metamorphic hydrothermal solution with geothermal water participated in the stratabound Au-Sb-W deposit which is with superimposed transformation.