溆浦地区脉型金矿床热液蚀变地球化学特征

Hydrothermal Alteration Geochemistry Characteristics of Vein-type Gold Deposits in Xupu Area

溆浦地区位于扬子地台南缘,江南古陆块西段的雪峰山弧形韧性剪切带中段,属湖南最重要的“金腰带”。区内脉型金矿主要热液蚀变有硅化、黄铁矿化、绢云母化、毒砂硫化物化、绿泥石化和碳酸盐化等;划分4个成矿阶段:变质-块状石英阶段→低硫化物块状石英阶段→硫化物细(微)晶石英阶段→石英-碳酸盐阶段,其中硫化物细(微)晶石英阶段是主要的金成矿阶段。矿化带化学成分表明石英脉中K、Al大量迁出而Si迁入,绢云母化带中Cu、Pb、Zn、Au、Co均大量迁入;蚀变带元素地球化学由核部往两侧呈现减少-富集-再减少的规律,其特征表明金成矿物质主要是沿断裂构造来自深部。

Xupu area is located in the middle section of the arc ductile shear zone of Xuefeng mountain in Ghiangnania western,it is the most important"golden belt"in Hunan.The mainly hydrothermal alterations of vein-type gold deposits include quartzfication,pyritization,sericitization,arsenopyrite sulphuretion,chloritization,carbonatization and so on in this area.It is divided into four mineralization stage such as metamorphic-block quartz stage to low sulfide-block quartz stage to fine(micro)crystalline quartz within sulfide stage to quartz-carbonate stage,and the fine(micro)crystalline quartz within sulfide stage is the mainly mineralization stage.The chemical composition of the mineralized zone is show that K and Al elements move out and Si element moves into quartz vein,and Cu,Pb,Zn,Au,Co elements massive immigration into sericitization zone,element geochemistry content presents decrease-enrichment-decrease again from core part to both sides in alteration zone,Its characteristics show that the gold ore-forming materials mainly come from the deep along the fault structure.