The Research On The Geochemical Characteristic And Genesis Of The Xushan Tungsten Deposit In Central Jiangxi

Xushan tungsten deposit in middle Jiangxi Province, located in the Middle East Qinhang combined belt, north margin of South China Caledonian fold belts, is a typical trinity type tungsten deposit with quartz type, granite type and skarn type tungsten mineralization, suitable for ore prospecting model of “upper vein and lower ore body” or “five floors+basement”. On the basis of summarizing the geological background and metallogenic characteristics of Xushan tungsten deposit, S, Pb isotopes and fluid inclusions researches are systematically carried out, the genesis mechanisms of the deposit are analyzed, and the metallogenic model of the deposit is preliminarily established. Several major understandings are as follows:(1) S, Pb isotopic geochemistry show ?34S values vary in the range of 0.2‰~4‰ with ?34S?S ranging from 1.1‰~4‰, indicating the sulfur in the ore is magma sulfur; 206Pb/204 Pb values are in the range of 18.133~18.711, 207Pb/204 Pb values are 15.605~15.669, and 208Pb/204 Pb values are 38.400~38.772, with a small range, revealing lead in the ore is from the crust.(2) Temperature measurement of fluid inclusions shows the homogenization temperatures of fluid inclusions in quartz veins mainly vary in the range of 370?~410?(early stage of silicates-oxides) and 170?~270?(late stage of oxides-sulfides) with salinity values range from 4~19 wt% NaCl. And the metallogenic fluids are estimated as 0.8~1.0g/cm3 in density, 13.6~46.4MPa in pressure and 0.45~1.70 Km in metallogenic depth, and salinity and density relation implies the metallogenic fluids have undergone mixing and boiling processes. Thus, the metallogenic fluids can be concluded as fluids with medium high temperatures, medium high salinity and low density, and are characterized by magmatic hydrothermal deposit with multi-periods and stages.(3) Former researches of petrology and metallogenic chronology of Xushan deposit show the metallogenic epoch is 147.1±3.4Ma, a little late comparing to its petrologic epoch(153~155Ma), indicating this ore deposit has a close relation with host rocks(Ziyunshan rock mass). Integrating S, Pb isotopes geochemistry characteristics and former researchers of trace elements of granite, the source of metallogenic materials can be known as the lower hidden granite rock mass.(4) By combining the metallogenic geological, stable isotopic geochemical, metallogenic fluids geochemical and petrologic metallogenic chronological features, Xushan tungsten ore deposit can be defined as a moderate high temperature pyrometasomatic deposit in late magmatic stage, closely related with magmatic activities, and its shape is controlled by NE,NNE fissure structure superimposed on axis and two wings of syncline of Huangjinling-Tiger mountain, which is a vital structure of ore controlling, carrying and hosting of the deposit.