| The Yushulin Deposit is a medium-sized silver-lead-zinc deposit located in the Baarin Left Banner,Inner Mongolia.The tectonic location is located in the eastern part of the Central Asian orogenic belt between the Siberian plate and the North China Craton,which is a middle area where the Paleozoic Paleo-Asian tectonic domain and the Mesozoic Pacific Rim tectonic domain strongly overlap.According to the division of tectonic units,the Yushulin deposit is located in the lead-zinc-silver-copper-tin-iron metallogenic belt in the southern part of the Da Hinggan Mountains.Based on detailed field geological surveys and comprehensive laboratory research,this paper systematically summarized the geological,ore geochemical,orebody,and surrounding rock alteration characteristics of the Yushulin deposit,combined with fluid inclusions,S isotopes,and dating data to compare regional typical deposite.The deposit is considered to be a medium-low temperature Hydrothermal vein type silver-lead-zinc deposit.The ore body of the Yushulin deposit is found in the metamorphic siltstone and silty slate strata in the upper section of the Dashizhai Formation.It is controlled by the structural fissures in the strata.The metal minerals are mainly pyrite,pyrrhotite,chalcopyrite,sphalerite,galena,a small amount of silver ore,and crimsonite.The gangue minerals include quartz,chlorite,biotite,and carbonate minerals.The mineralization can be divided into two periods: hydrothermal mineralization period and superficial mineralization period and divided into four stages: quartz-pyrite sulfide stage,quartz-polymetallic sulfide stage,and quartz-carbonate stage and superficial oxidation stage.Surrounding rock alterations are mainly silicification,potassiumization,sericitization,chloritization,and carbonate formation,Silicification and sericite are Prospecting sign.Diorite porphyrite closely related to mineralization is rich in large ion-philic elements such as Rb,Th,U,and K,and loses high field strength elements such as Sr,P,and Ti.The rare-earth element distribution curve belongs to right-inclined light rare earth.Enrichment type,negative Eu anomaly,obvious fractionation of light rare earth and heavy rare earth.The age obtained by LA-ICP-MS zircon U-Pb dating is 143.1±0.6Ma,which is Early Cretaceous.Fluid inclusion studies show that the type of inclusions is mainly rich-liquid inclusions,and the fluids are medium-low temperature?170260??,low salinity(2.48% NaCleqv),and low density?0.680.94g/cm3?fluid.The ?34SCDTvalues of all the isotopes of sulfur are between-0.12.4‰,which are consistent with the characteristics of mantle-derived fluids,showing that the ore-forming materials originate from deep-source magma.In summary,the deposit was formed in the Early Cretaceous,and the ore-forming materials originated from deep-source magma.It is a Medium-low temperature Hydrothermal vein type silver-lead-zinc deposit Formed in the late YanShan period. |
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