Study On Fluid Inclusions Of The Zhangdou Tungsten Deposit In Southern Jiangxi

Zhangdou tungsten deposit is located in Dayu,which is a typical quartz vein wolframite deposit in Southern Jiangxi.Based on the detailed field geological survey,this paper studied the microthermometric,the laser Raman,the explosive gas-liquid phase composition and the rare earth,trace elements,etc.,in the quartzite inclusions symbiosis fluid inclusions in wolframite-quartz veins of the Zhangdou tungsten deposit.,in order to identify the nature and source characteristics of the fluid inclusions in the Zhangdou tungsten deposit,and try to discuss the evolution characteristics of the fluid and the metallogenic mechanism of the ore and tungsten mineralization,which mainly have the following understanding:(1)The fluid inclusions in tungsten-containing quartz veins are well developed,the main types of fluid inclusions is pure liquid inclusions(type?)and pure vapor inclusions(type?)and gas-liquid two-phase inclusions(type ?),(type ?a)are the major types.(2)The results of microthermometric of fluid inclusions show that the homogenization temperature of fluid inclusions is between 125 and 272 ?,with an average value of 192.8 ?,which is mainly between 180 and 220 ?,showing a distinct unimodal feature,indicating that Zhagndou tungsten deposit haved experienced one stage of hydrothermal activity at least,the inclusions have a salinity of between 0.18 wt%NaCleq and 6.01 wt% NaCleq,with an average value of 3.09 wt% NaCleq,mainly between 3 wt%NaCleq and 4 wt%NaCleq,The density is between 0.79 and 1.04g/cm3,mainly between 0.85 and 0.92g/cm3,and the ore-forming pressure is between 10 and 80 MPa,which mainly between 50~60 Mpa,for the medium pressure metallogenic areas;mineralization depth distribution in the 1~5km,mainly in the depth of 4 km range,showing a moderate depth of the mineralization environment.These shown that the a hydrothermal fluid of the Zhangdou tungsten deposit are medium-low temperature,low salinity and medium density hydrothermal fluids.The mineralization process is mainly in the medium pressure and medium depth mineralization environment.(3)Analysis of laser Raman composition and group fluid inclusions burst analysis of single fluid inclusions showed that the main component of gas phase is H2 O,H2,N2,CO,little of CH4 and CO2,The main components of liquid phase of ore-forming fluid are SO42-,Cl-,F-and NO3-,and the main cation is Ca2+,Na+,K+ and Mg2+.The composition of gas and liquid components in fluid inclusions may explain the multi-source of ore-forming sources,and the evolution process of ore-forming fluids may be mainly in the relatively oxidized environment.(4)The results of trace element analysis of fluid inclusions show that the elements Zn,Mo,Cs,W and Bi are relatively enriched in the ore-forming fluid,and the remaining elements show different degrees of loss.The value of Co/Ni is 0.01~0.04,the mean value is 0.02,the Mo/W value is 0.09~37.71,the mean value is 5.36,the Ga/Tl value is 0.09~2.78,the mean value is 1.25,suggesting that the ore-forming fluid,while the precipitation and metamorphic water and other sources of fluid mixed.(5)Through the above analysis,it can be concluded that the mixing of different source fluids may be the main mineralization mechanism of the Zhangdou tungsten deposit.The evolution process of the ore-forming fluid may occur mainly in the relatively oxidized and weak alkaline environment.The polymetallic ore-forming fluids cause the enrichment and precipitation of tungsten and polymetallic metals due to the significant changes in the physical and chemical conditions of the metallogenic environment.