Characteristics Of Ore-Forming Fluids And Metallogenic Potential Of Bianjiadayuan Molybdenum-Lead-Zinc Polymetallic Deposit In Inner Mongolia

Linxi County,Chifeng City,Inner Mongolia Autonomous Region is located in the southern section of the Greater Xing'an Mountains,which belongs to the overlapping position of the Paleo-Asian Ocean mineralization domain and the west pacific marginal mineralization domain,and have a lots of Mo,Sn,Cu,Pb and Zn deposits.The Bianjiadayuan Mo-Pb-Zn deposit is located in the southwest of Linxi County.The main minerals are Pb,Zn,Ag,Mo and Sn.The ore bodies are Pb-Zn-Ag vein ore body,Pb-Zn breccia ore body and Mo-Sn-Cu porphyry ore body.The paper combines regional and mineral research results with the use of field geological exploration,indoor petrography and mineralogy studies,fluid inclusion microscopic temperature measurement,H-O isotope composition tracing,etc.The geological characteristics of the deposits and the characteristics of ore-forming fluids are revealed.The genesis and prospecting indicators of the deposits are described,the metallogenic model is established,and the ore-forming potential of the deep deposits is evaluated.The following points are obtained:1.There are three types of ore bodies in the mining area,namely porphyry ore bodies,breccia ore bodies,and vein ore bodies;the ore types are tin-molybdenum?copper?quartz porphyry ore,Lead-zinc?copper?breccia type ore,lead-zinc-silver vein ore;mineralization stage is divided into five phases,respectively quartz-pyrite mineralization stage,molybdenite-cassite mineralization stage,sphalerite-galena mineralization stage,silver polymetallic sulphide mineralization stage,quartz-calcite mineralization stage;wall-rock alteration has the silicification,sericitization,pyritization,kaolinization,chloritization,epidotization,carbonation,and fluoritization,obviously controlled by temperature.The results of microscopic temperature measurement of fluid inclusions show that the fluid inclusions contain two types:H₂O fluid inclusions and CO₂-H₂O fluid inclusions.The ore-forming fluid has medium-high temperature,medium-low salinity and low density characteristics.And from quartz-pyrite mineralization stage to quartz-calcite mineralization stage,the ore-forming fluid has changed from high temperature to low temperature,from medium salinity system to lower salinity system,and density gradually increases.the trend of.3,H-O isotope composition shows that the main source of ore-forming fluids of the molybdenum-lead-zinc polymetallic deposit in the Bianjiadayuan compound is magmatic hydrothermal fluid.From the mineralization stage of the sphalerite-galaline ore-forming stage,there is a large amount of atmospheric precipitation.The incompatibility of CO₂ components enriched in ore-forming fluids,fluid immiscibility and the incorporation of atmospheric precipitation are the main reasons for the precipitation of ore-forming materials in the molybdenum-lead-zinc deposits of the Bianjiadayuan.4.According to the comparison and analysis of ore-forming fluid characteristics,the magnetic method and drilling engineering data,it is considered that the porphyry ore body has the the deep ore-forming potential.