Study On The Origin And Genesis Of Metallogenic Materials In Baiyun Gold Deposit In Eastern Liaoning Province

The Liaoning Baiyun Gold Mine is a typical large-scale gold deposit in the Liaodong-Jinan Rift.Because of the long geological evolution of the ore-bearing rock system in the gold deposit area,the Liaohe Group was influenced by multiple stages of tectonic magmatism,and the metallogenic geology was complicated.So there are some controversies about the origin of metallogenic material and the genesis of Baiyun gold deposit.This paper focuses on the research on the source and cause of mineralization of the Baiyun Gold Mine.Based on the extensive collection and collation of previous work,the field geological profile survey and core cataloging have been carried out.On the basis of fully understanding the geological characteristics of the deposit and the output characteristics of the ore body,I deeply analyzed the main quantities,trace elements,isotope geochemistry and other characteristics of the ore and surrounding rocks of the ore deposits in the area,and traced the source and analysis of the mineralization genesis of the deposit.The Baiyun Gold Mine occurs in the strata of the Gaixian Formation and Dashiqiao Formation of the Liaohe Group.Ore bodies are controlled by near-east-west strike faults and their secondary faults.The ore types mainly include altered rock type and quartz vein type.The ore body appears to be layered,lenticular,and large veined.The main ore mineral is pyrite,followed by chalcopyrite,galena,sphalerite,etc.Wall-rock alteration mainly includes silicification,potassic alteration,pyritization,s ericitization,chloritization and carbonatization.The comprehensive data of fluid inclusions show that the homogenization temperature is mainly concentrated at 200?250?,and the salinity is mainly 0.35%?19.21%wt.NaCl,indicating that the ore-forming fluid is a kind of medium-temperature low-salinity fluid.The ³⁴S value is-12.5‰to 1.9‰,which is rich in ³²S and poor in ³⁴S.It is the smallest geological body of ³⁴S in the area,indicating that the ore-forming elements are not from wall-rocks or veins,but from magmatic heat liquid.The ²⁰⁶Pb/²⁰⁴Pb value of the pyrite in the ore is 17.416 to 18.908,the ²⁰⁷Pb/²⁰⁴Pb value is 15.511 to 15.714,and the ²⁰⁸Pb/²⁰⁴Pb value is 35.541 to40.032.According to the ²⁰⁷Pb/²⁰⁴Pb-²⁰⁶Pb/²⁰⁴Pb diagram,the Triassic granite and Gaixian Formation may be the source of ore-forming metals.The H-O isotope data of ore-bearing quartz in Baiyun Gold Deposit shows that the value of?¹⁸O_V-SMOW-SMOW was at least-1.1‰and at most 15.9‰,with an average value of 11.4‰and a range of17.0‰.The value of?D_V-SMOW-SMOW is-108.3‰at the minimum,-10‰at the maximum,and-90.2‰at the average,with a range of 98.3‰.The?¹⁸O-?D diagram shows that the ore-forming fluids are derived from magmatic water and atmospheric water,and are mainly magmatic water.The He-Ar isotope value?0.43Ra?0.52Ra?is significantly higher than crust-derived fluid and lower than mantle-derived fluid.The ³He-⁴He diagram shows that the fluid is mainly a mixture of crust-mantle fluid and mainly crust-derived fluid.Based on the understanding of the geological characteristics of the deposit,combining the characteristics of fluid inclusions,S isotopes,Pb isotopes,He-Ar isotopes,it is believed that the ore-forming materials mainly come from magmatic hydrothermal fluids,and the stratum materials of the Liaohe Group are added to different degrees.The type of deposit belongs to the middle and low temperature magma hydrothermal type.