Study On Ore-Forming Fluids Of The Arqiale Lead-Zinc Deposit In Zhaosu,Xinjiang

The lead-zinc Arqiale deposit is situated in the northwest of the Yishijilike metallogenic belt in the West Tianshan.The regional structure is an island arc environment in the process of subduction of the early Carboniferous paleooceanic.The Arqiale deposit is situated on a monoclinic structure,with the whole strata towarding to the east-west and trending to north-west direction.The ore bodies which occur in the Akeshake Formation limestone strata are flat,lenticular and layered,which local perforation.The unconformity overlayed the volcanic rocks of the Dahalajunshan Formation.The widely developed actinolite alteration in the ore district is the direct prospecting indicator of lead-zinc.However,the genetic mechanism of the deposit has been divergent.This paper studyed the micro-thermometry of fluid inclusions around underground samples collected from the mine.Considering the structural fluid inclusions,ore structure,mineral assemblages of the Arqiale lead-zinc deposit,it is found that the characteristics of the Arqiale lead-zinc deposit are in good agreement with those of the skarn type lead-zinc deposit.Therefore,it is considered that the Arqiale is a skarn type lead-zinc deposit.Characteristics of inclusions and ore-forming fluids in different stages of skarn:1)Early skarn stage: There are fluid inclusions(LV,VL and S type)in garnet.The homogenization temperature is 411-548 ? and the salinity is 41.1-58.8 wt.% Na Cl eqv.It is a high temperature and high salinity system.Fluid immiscibility is an important mechanism for mineral formation in this stage.2)Late skarn stage,only LV fluid inclusions exist in the Yanglithiasis.The homogenization temperature ranges from 321-447? and salinity varies from 1.1-15.7 wt.% Na Cl eqv.Ore-forming fluid is characterized medium-high temperature and medium-high salinity.The H and O isotopes characteristics of the actinolites indicate that metamorphic fluid and formation fluid had been added in this stage,that is,fluid mixing is an important mechanism of mineralization in this stage.3)Early quartz-sulphide stage: LV-,V-,VL-and L-type fluid inclusions exist in quartz,and there are few CO2 and CH4.The homogenization temperature is 157-357?,salinity is 0.4-10.0 wt.% Na Cl eqv.,ore-forming fluid is characterized by low-medium temperature,low-medium salinity and weak oxidizing.Fluid immiscibility leads to mineralization.4)Late quartz-sulphide stage: LV-,V-,VL-and L-type fluid inclusions exist in calcite and sphalerite with homogenization temperature of 91-278 ? and salinity of 0.4-8.3 wt.% Na Cl eqv.The ore-forming fluids are characterized by low-medium temperature and low salinity.The fluid immiscibility and meteoric water lead to the occurrence of mineralization.