湘东北横江冲金矿床黄铁矿微量元素特征及其对成矿机制的指示OA

The Jiangnan Orogenic Belt is a significant gold-polymetallic metallogenic belt in South China,with total identified gold resources reaching nearly 1,000 tons.Northeastern Hunan region,situated in the central segment of this belt,hosts three major gold districts:Wangu,Huangjindong,and Liling,all of which record multiple episodes of gold mineralization.While previous studies have provided substantial insights into Indosinian and Yanshanian gold mineralization events in this region,research on Caledonian gold mineralization remains relatively limited,and the genesis of these gold deposits requires further clarification.The Hengjiangchong Gold Deposit,located in the Liling gold orefield,is a typical Caledonian gold deposit in the central Jiangnan Orogenic Belt.However,key aspects such as its trace element geochemical characteristics,evolution of ore-forming fluids,and gold enrichment mechanisms are still poorly understood,which constrains a comprehensive understanding of this mineralization processes.Based on detailed field geological investigations,this study divides the mineralization of the deposit into three stages:(I)Quartz-Pyrite-Arsenopyrite Stage,(II)Quartz-Pyrite-Polymetallic Sulfide-Native Gold Stage,and(III)Quartz-Calcite Stage.Within these seven generations of pyrite have been identified euhedral granular pyrite(Py1)from Stage I,exhibiting core(Py1a)-mantle(Py1b)-rim(Py1c)textures;Stage II includes anhedral patchy Py2a in altered wall rocks and porous Py2b,as well as pyrite in smoky-gray quartz veins with a porous core(Py3a)and a homogeneous rim(Py3b).Mineralogical and trace element geochemical analyses reveal that gold was primarily transported as gold-bisulfide complexes[Au(HS)2-]and eventually incorporated into pyrite as solid-solution gold(Au+).Integrated with previous research,we propose that dissolution-reprecipitation and wall rock sulfidation were the principal mechanisms controlling gold precipitation in this deposit.