查看更多>>摘要：The Jiadi and Damaidi gold deposits in south-west Guizhou Province are the largest basalt-hosted Carlin-type gold deposits recently discovered in China.This study uses the Tescan Integrated Mineral Analyzer,supported by detailed field investigations,regional geological data,and extensive sample collections,including mineralized ore,altered wall rock,and unaltered basalt samples,for ore-bearing and geochemical analyses.Comparative analysis between altered and unaltered basalt samples revealed a mineral assemblage of sericite,quartz,and pyrite.This min-eral composition forms through the hydrothermal alteration of unaltered basalt,originally containing feldspar,pyrox-ene,and ilmenite.The wall rock primarily features sericite,quartz,and hematite.During the alteration process,major,trace,and rare earth elements notably migrate.In the Jiadi deposit,K2O,Rb,Au,and REE significantly increase,while Na2O,CaO,MgO,and MnO decrease.SiO2,Al2O3,and Fe2O3 levels remain relatively stable.In the Damaidi deposit,K2O,Rb,and Au enrich,contrasting with the deple-tion of Na2O,CaO,MgO,and MnO,while SiO2,Fe2O3,Al2O3,TiO2,and REE show no significant changes.In the wall rock,TiO2,Al2O3,K2O,and REE increase,while Na2O,CaO,MgO,and MnO decrease;SiO2 and Fe2O3 content remains unchanged.The mineralization process likely origi-nated from mid-to low-temperature,reductive magmatic hydrothermal fluids rich in CO2,CH4,N2,H+,S2-,HS-,H3AsO3,and[Au(HS)2]-.These fluids migrated to tectoni-cally weak zones in the Lianhuashan area,where Emeishan basalts are present.They reacted with Fe-bearing minerals in the basalt,such as ferro-hornblende and ilmenite,forming pyrite,arsenic-bearing pyrite,and arsenopyrite,thus enrich-ing Au in these minerals.Additionally,K+and H+in the fluid reacted with plagioclase in the basalt,forming sericite and quartz.As the fluid entered the wall rock from structural weak zones,its oxidation increased,leading to the complete or partial reaction of Fe-bearing minerals in the wall rock,resulting in the formation of hematite or magnetite.This mineralization process is similar to that observed in carbon-ate-hosted Carlin-type gold deposits in southwest Guizhou,with the primary distinction being the iron source.In car-bonate deposits,iron originates from ferridolomite within the wall rock,while in basalt-hosted deposits,it derives from ferripyroxene and ilmenite.
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