Metallogenic Relationship And Prospecting Significance Between Fluorite Deposits And Lead-Zinc-Silver Polymetallic Deposits In The Linxi Area,Inner Mongolia

The Southern Great Xing'an Range?SGXR?with excellent ore-forming geological conditions is located at the superposition of the Paleo-Asian Ocean Metallogenic Province and the Pacific Rim Metallogenic Province.It is an important Sn-Cu-Mo-Ag-Pb-Zn metallogenic belt and fluorite mineral resources gathering area in northern China.The fluorite deposits are in coexistence with metal deposits within the same region.However,most studies only focused on different types of deposits in the study area respectively,but the research on the relationship between fluorite deposits and polymetallic deposits is not enough,and the research is minimal.In this paper,based on the aspects of geological characteristics,diagenetic chronology and metallochronology,fluid inclusions,stable isotopes and rare earth elements,this paper takes the representative area of Linxi as an example to discuss the genetic correlation between fluorite deposit and Ag-Pb-Zn polymetallic deposit,summarizes metallogenic regularity and guides the prospecting prediction.The main results of the study are as follows:1.This study considers that a series of porphyry tin-molybdenum-copper deposits,hydrothermal vein-type silver-lead-zinc deposits,and vein fluorite deposits developed in the Early Cretaceous in the Linxi area belong to a unified tectonic-magmatic-hydrothermal mineralization system and are closely related in time,space and genesis.2.The fluorite deposits in the study area are closely related to the silver-lead-zinc polymetallic deposits in the spatial proximity.The metallochronology studies show that the two types of deposits belong to the early Cretaceous peak of mineralization in the SGXR.The ages of metal deposit range from 130 to 145Ma,and the ages of fluorite deposits range from 132 to 137Ma.The age of fluorite deposits was slightly later than that of polymetallic deposits.3.Characteristics of ore-forming fluids indicate that porphyry tin-copper-molybdenum mineralization,hydrothermal vein type silver-lead-zinc mineralization,fluorite mineralization ore-forming fluids evolve from medium-high temperature,medium-high salinity fluids to medium-low temperature and low salinity fluids.The source of ore-forming fluids tends to evolve from magma water to atmospheric precipitation.4.Fluorite mineralization is generally developed in the silver-lead-zinc polymetallic deposits in Linxi area.According to the characteristics of mineral symbiosis,fluid inclusions,stable isotope characteristics and rare earth element composition,the fluorite mineralization in the study area can be divided into three stages.From the first stage to the third stage,the relative enrichment of LREE changed to the enrichment of HREE.?1?fluorite of stage I is symbiotic with metal sulfides such as molybdenum and chalcopyrite.The ore-forming temperature is between 270 and 350°C and contains CO₂-bearing inclusions.The ore-forming fluid mainly originated from magmatic water,and the total amount of rare earth elements is more than 500ppm;?2?fluorite of stage?is symbiotic with metal sulfides such as galena and sphalerite,and the small-sized gas-liquid two-phase inclusions with mineralization temperature of200-270°C,the ore-forming fluid originated from the mixture of magmatic water and meteoric waters,the total amount of fluorite rare earth elements is between 20 and 170ppm;?3?fluorite of stage?mainly forms independent fluorite deposits and late stage fluorite in metal deposits,and the ore-forming temperature is between 130 and 260°C.The total amount of fluorite rare earth elements varies greatly,with a minimum of about5 ppm and a maximum of 200 ppm.From the first stage to the third stage,the REE characteristics evolved from the relatively enriched LREE to the enriched HREE.5.Based on the analysis of time,space and genetic relationship between fluorite deposit and silver-lead-zinc polymetallic deposit in the study area,this thesis constructs the metallogenic model of early Cretaceous tectonic-magmatic-hydrothermal metallogenic system between polymetallic deposit and fluorite deposit and also sorts out the prospecting mark and guides the prospecting prediction.This study suggests that that the geochemical anomaly of Cu,Pb and Zn around the Wujianfang fluorite deposit in the study area is obvious,and the fluorite mineralization features reveal the prospecting potential of the silver-lead-zinc polymetallic deposit.