Geological Characteristics And Element Geochemistry Of The Huijiabao Gold Orefield, Southwest Guizhou

Huijiabao gold field is one of the type localities in the ore concentration area of Carlin-type gold deposits in Southwestern Guizhou.It is located at the intersection of the southwest margin of Yangtze Para-platform and Youjiang fold belt in the South China fold system.Huijiabao gold field mainly consists of Shuiyindong super-large gold deposit,Zimudang large gold deposit,Taipingdong large gold deposits some other gold deposits?points?.Orebodies of Huijiabao gold field are mainly present in unpurified carbonatite of Upper and Lower Triassic and obviously controlled by Huijiabao anticline and secondary faults.The ore bodies mostly are stratiform,veinlike and occur in the fault structure and interlayer fracture zone.Ore texture mainly is euhedral or subhedral texture,zonal texture and metasomatic texture,ore structure are dominated by disseminate,veinlike and brecelated.The main ore minerals include pyrite,arsenopyrite and native gold,gangue minerals are calcite,quartz and dolomite.Gold was present in crystal defeat of pyrite and arsenopyrite in the form of enclosed gold.The predominant wall-rock alteration is the decarbonation of carbonates,pyritized,silicification and carbonatization and closely to the formation of gold in the gold field.The study of trace elements showed that elements in ore-forming elements association?Au-As-Sb-Hg-Tl?in Carlin-type gold deposit have a better correlation and a higher enrichment coefficient.The results of rare earth elements?REE?distribution patterns revealed that light REE relatively enriched in the region and Eu was slightly negative anomaly in ore,mineralized rock and wall rock,the ore recorded REE characteristics.We have calculated elements migration by using of Grant mass balance equations,it indicated that ore-forming elements association?Au-As-Sb-Hg-Tl?of the Carlin-type gold deposit reflected gain in the wall rock alteration during the mineralization process,migration showed an increasing tendency with the deepening of mineralization degree.The migration SiO₂ and CaO and the decarbonation of carbonates,silicification and carbonatization by microscopic observation have corroborated.Based on fluid inclusion composition data of Shuiyindong gold deposit,we carried out geochemical thermodynamics calculations and obtained that gold in the ore-forming solution mainly migrated in the form of AuHS⁰ complex.We came to the conclusion that the precipitation of gold is related to sulfurization of ore-forming fluids and wall rocks and elevated pH values.Finally,the author summaries the gold precipitation mechanism in the mineralization process of Carlin-type gold deposits in Southwestern Guizhou.