Geochemical Characteristics And Metallogenic Mechanism Of Ore-forming Fluids In The Azhahada Cu-Bi Deposit, Inner Mongolia

The Azhahada Cu-Bi deposit in Inner Mongolia is located in the northeastern part of Abaga Banner,Inner Mongolia.On the basis of collecting and collating relevant data,I have carried out fluid inclusions and C-O-S-Pb isotope studies on the Azhahada Cu-Bi deposit through field exploration and laboratory study,and discussed the properties of ore-forming fluids,the sources of ore-forming materials as well as the genesis of deposit.The major results are as follows:?1?According to the interpenetrating relationship between veins and mineral combination characteristics,this study divides three metallogenic stages:quartz-chalcopyrite-pyrite stage;quartz-chalcopyrite-pyrite-bronze ore-stibnite stage;quartz-calcite stage.?2?The fluid inclusion data shows that the fluid inclusion type is mainly gas-liquid phase,and the size of the inclusion is less than 10?m.The average temperature of the ore-forming fluid is 260.2?,and the average salinity is 15.4 wt.%NaCl equiv.Laser Raman spectroscopy experiment data show that the fluid inclusion components are mainly H₂O and CH₄,and the ore-forming fluid belongs to the medium-low temperature,medium-high salinity H₂O-NaCl±CH₄ system.?3?Carbon and oxygen isotope results indicate that the source of ore-forming materials is magmatic fluid and atmospheric precipitation.The?³⁴S_V-CDT value in the pyrite sample ranges from 1.3‰to 9.5‰,indicating that the ore-forming material provides some mineralization in addition to the magmatic hydrothermal fluid.?4?The ²⁰⁶Pb/²⁰⁴Pb value of the Pb isotope of the pyrite sample ranges from 18.27-18.383;the ²⁰⁷Pb/²⁰⁴Pb value ranges from 15.561-15.602;the ²⁰⁸Pb/²⁰⁴Pb value ranges from 38.081 to 38.229.The lead isotope structure mode is near the orogenic belt mean line,indicating that the ore-forming material source is the mixed source of each reservoir.The comprehensive analysis shows that the mixing of fluids is an important mechanism leading to the enrichment and sedimentation of ore-forming elements in the Azhahada Cu-Bi deposit.The deposit belongs to the medium-low temperature hydrothermal quartz vein deposit.