| Juyuan tungsten deposit is one of the few large quartz vein type scheelite deposits in South China.On the basis of detailed field geological survey,a series of studies on inclusions in ore-bearing quartz veins and tungsten-bearing minerals have been carried out by means of alpha particle track etching,optical microscopy,Scanning Electron Microscopy,Electron Probe,Laser Raman and inclusion microthermometry.Combining with previous research results,the characteristics and sources of ore-forming fluids and the mineralogical behavior of tungsten in metallogenic process of Juyuan tungsten deposit.Research shows:Five types of inclusions were found in ore-bearing quartz of Juyuan tungsten deposits,including liquid-rich two-phase fluid inclusions,vapor-rich two-phase fluid inclusions,onephase fluid inclusions,CO2-containing three-phase fluid inclusions and daughter-mineral containing inclusions.And liquid-rich two-phase fluid inclusions are the main ones.The homogenization temperature of liquid-rich two-phase fluid inclusions mainly concentrates at 283-395?,and the salinity range is 0.66-6.24wt%Na Cl.Fluid inclusions of quartz in Juyuan tungsten deposits have the characteristics of medium-high temperature and mediumlow salinity.Compared with the overall level of quartz vein tungsten deposit,the temperature is higher and the salinity is slightly lower.Laser Raman measurements show that the gas phase is dominated by H2O,CO2,followed by CH4 and N2,and the liquid phase is dominated by H2O,in addition,CO32-.The ?D value of the ore-forming fluid of Juyuan tungsten deposit ranges from-68.3‰ to-58.6‰,and the ?18O? value of the ore-forming fluid ranges from 5.1‰ to 7.5‰,Most of them are within the range of magmatic water,while a few are near the magmatic water area and migrate to the direction of atmospheric precipitation line.The ore-forming fluids mainly come from magmatic water,and there are different degrees of atmospheric precipitation mixed in the later stage.The formation of tungsten minerals in Juyuan tungsten deposit can be divided into four stages: ?.tungsten mainly enters into oxides rich in Nb and Ti,forming tungsten-rich minerals such as columbite,W-Ferrocolumbite,Ti-Ferrocolumbite,Yttrium Aeschynite,and a very small amount of tungsten enters wolframite and scheelite in the early stage;?.columbite,W-Ferrocolumbite,Ti-Ferrocolumbite,Yttrium aeschynite are metasomatized by later fluids to form containing tungsten Qitianlingite,Manganocolumbite and Ti-rich Yttrium aeschynite.?.tungsten enters the middle stage of scheelite,which is also the main mineralization stage of tungsten;?.tungsten enters the late stage of scheelite.There are abundant tungsten minerals in Juyuan tungsten deposit,mainly scheelite,but most scheelite minerals are formed after Qitianlingite,Aeschynite family of mineral,columbite family of mineral and wolframite.It shows that in the evolution of ore-forming fluids,the vast majority of W first enters rich in Nb and Ti tungsten-bearing minerals and wolframite,followed by a large number of crystallization of scheelite.This phenomenon may be related to the higher metallogenic temperature of Juyuan tungsten deposit. |
PDF Full Text Request