Characteristics And Evolution Of Ore-forming Fluids And Mineralization Model For Yaogangxian And Xitian Quartz Vein Type Tungsten Deposit, Hunan

Located at northern rim and southern rim of the Chaling- Chenzhou deep fault, in Southeast of Hunan, the Yaogangxian tungsten deposit and Xitian tungsten-tin polymetallic deposit are the typical deposits of quartz-vein type tungsten deposit in Nanling metallogenic belt north rim.In this paper, based on geological characteristics of metallogenic geological body. Sampling and identification of the characteristics of geological body. By means of EPMA analysis experiment, homogenization temperature of the fluid-inclusion testing experiment, melt-inclusions heating melt and LA-ICP-MS experiment. Established the ore-forming fluid evolution model and mineralization mechanism.1. The research on fluid-melt inclusions of greizenschieren indicate that a complete successive evolutionary process of tungsten deposit’s ore-forming fluid is actually from granitic lava state to lava-fluid transitional state, and then to magmatic hydrothermal state,and the characteristic of ore-forming fluids is rich in volatiles. The further fluid evolution, the further enrichment of volatiles and ore-forming materials. Eventually forming the wolframite quartz-veins.2. Mineralization related to ore-forming fluid immisciblility. Fluid inclusions studies have shown that there are two times immiscibility appears during ore-forming fluid evolution. The first is magmatic fluid stage, of which the ore-forming fluid is lava-hydrothermal transitional fluid. The second is hydrothermal stage, of which the ore-forming fluid is hydrothermal fluid. The result of ore-forming fluid immisciblility is forming clathrate which is due to supersaturated volatile in ore-forming fluid complex with tungsten. These clathrates by precipitation and decomposition, eventually leading to mineralization.3. Mineralization is due to the magmatic differentiation, Through the magma fluid, lava-hydrothermal transitional fluid and hydrothermal fluid. This paper studies suggest that the mineralization of quartz-vein tungsten already began during the magmatic, and continue to later magmatic hydrothermal stage.Traditional metallogenic model of magmatic hydrothermal deposit represent only a part of metallogenic evolution of the quartz-vein type tungsten deposit. Previous prospecting work is mainly for magmatic hydrothermal alteration features. In this paper, besides perfecting the types of ore deposit metallogenic evolution mode, it also has practical significance for ore-prospecting work.