Studies On Geological Characteristics And The Origin Of Ore-forming Materials Of Laozhaiwan Gold Deposit, Yunnan Province

“Golden triangle” area bordered on Yunnan-Guizhou-Guangxi was one of themost important Carlin-type gold deposits concentration areas. Deep understanding ofCarlin-type gold deposits in Guizhou and Guangxi Province had reached throughseveral decades studies, but geological environment was very complex in thesoutheastern Yunnan, and Carlin-type gold deposits produced in the southeasternYunnan were different from that of America, few studies were taken there. Based on alarge number of field work, studies on the geological characteristics combining withgeochemistry characteristics were taken, and analysis the genesis of Laozhaiwan golddeposit.Studies on Laozhaiwan gold deposit were mainly about：（1）searching for theorigin of ore-forming fluid through fluid inclusions geology and H-O isotopegeochemistry;（2）estimating the ore-forming material source and analyzing thegenesis of the deposit through element geochemistry and S, Pb isotope geochemistry.According to the fluid inclusion test results and fluid density and salinity,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in lowtemperature and low salinity.According to composition of fluid inclusion analysis, combining with H-Oisotope, made the δD-δ18O figure, showed that the fluid of the deposit rooted information water and mixed with meteoric waters later.Major and trace elements geochemistry showed that quartz sandstone type oresand pyrite ores contained more gold. Studies on rear earth elements showed that themetallogenic material mainly from the wall rocks.S isotope test value showed that S in the metal sulfide was mainly from strata.According to the lead isotopic compostions and relevant calculation parameters，made the lead isotopic compostions scheme and△γ-△β scheme, showed that leadisotope mainly came from the upper crustal.In conclusion, in this paper, we study the source bed of Laozhaiwan gold depositthat was formed in the sedimentary diagenesis process, the activation migration of Auin source bed were caused by the action of fluid, and after that under the effect ofmultiple fluid circulation, activation of the Au migrated along the fault fracture zone and unconformity surface composite section, alteration metasomatic ore formationformed silicification, pyritization and related carlin-type gold deposit.