Fluid Inclusion Characteristics And Ore Genesis Of The Tiyier Gold Deposit In Western Junggar,Xinjiang

The Tiyier gold deposit is located at the north of the Dalabute fault in the south of western Junggar,which is a magmatic hydrothermal gold deposit related to the andesitic porphyrite located in Hatu-Baogutu ore concentration area.In this paper,the study take ore body-?of Tiyier gold deposit as the research object,this paper use fluid inclusion,H-O isotope analysis and Electron microprobe analysis,to discusses the characteristics of metallogenic fluid and the genetic mechanism of ore deposit,which is significant to find out the genesis of ore doposit and mine prospecting.The major outcropped strata of Tiyier mining area are Carboniferous Terraquilla Formation(C_1t)marine volcanic rocks.The ore-body is hosted in andesite porphyrite,controlled by NE faults structure.The hydrothermal mineralization period is divided into four stage:potassium feldspar-quartz stage,quartz-pyrite-Au stage,quartz-Au-sulfide stage,carbonate-quartz stage.The ore type is mainly altered rock,quartz vein is second.Metallic minerals are mainly pyrite,chalcopyrite,pyrrhotite,arsenopyrite,galena and native gold.Non-metallic minerals are mainly feldspar,quartz and calcite.Silicification,k-feldsparthization and pyritization are common alterations.The study of Fluid inclusion study shows that the type of the inclusion of the Tiyier deposit is mainly composed of liquid-rich aqueous inclusions(type L)and pure aqueous liquid inclusions(type P).Microscopic measurement results show that the homogenization temperatures of stage?range from 300?to 320?,with the average salinity of 4.7%Na Cl eqv.The homogenization temperatures of stage?range from 240?to 280?,with the average salinity of 3.0%Na Cl eqv.The homogenization temperatures of stage?range from 200?to 240?,with the average salinity of 2.6%Na Cl eqv.The homogenization temperatures of stage?range from 140?to 180?,with the average salinity of 2.2%Na Cl eqv.It can be seen from each stage that the homogenization temperatures and salinity decrease gradually.Combined with the analysis of laser Raman study,the metallogenic fluid belong to H₂O-Na Cl±CH₄±H₂S±C₆H₆ systerm of weak reducing fluid,with moderate-low temperature,and low salinity.The H-O isotope study shows that the early stage of metallogenic fluid is mainly magmatic hydrothermal fluid,which is mixed with meteoric precipitation in the later stage,indicaes that the mixed characteristics of the fluid,which may be an important mechanism for ore-forming material precipitation.The Electron microprobe analysis shows that the content of Fe and S in the pyrite of the Tiyier gold deposit is lower than the theoretical value.Depleted in Fe and S,the content of Co,Ni and Co/Ni ratios indicate that the pyrite is of hydrothermal origin.The ratio of n(Fe+Cu)and n(S)of chalcopyrite and the typomorphic characteristics of pyrrhotite define the temperature of main mineralization stage of the ore deposit range from 200?to 254?.The fineness of native gold indicaes that the native gold is the product of magmatic hydrothermal deposit under medium temperature.Based on geological characteristics,fluid inclusions,H-O isotope,and electron microprobe,the Tiyier deposit is interpreted as a magmatic hydrothermal deposit which is controlled by andesite porphyrite.