河南老湾金矿床成矿流体性质与同位素地球化学示踪

The properties of ore-forming fluids and isotope geochemical tracing of the Laowan gold deposit,Henan Province

老湾金矿床是河南桐柏地区典型的剪切带型金矿床。流体包裹体特征显示成矿流体为中低温、低盐度的含CO_2的K^+-Na^+-Cl^-SO_4^(2-)体系;氢氧同位素研究结果显示矿床成矿早期阶段以岩浆水为主要成矿热液来源,成矿晚期阶段以大气降水为主要热液来源:矿石铅同位素特征显示成矿物质源区与龟山岩组、老湾花岗岩有亲缘关系,且与花岗岩接近,显示其深源特征,进一步提供了成矿流体岩浆成因的证据。

The Laowan gold deposit is one of the typical shear zone type gold deposits in Tongbai area, Henan Province. The characteristics of fluid inclusions suggest that the ore-forming fluid is a K＋_Na＋-Cl-SO42- system which indicates medium-low temperature, low-salinity and CO2-containing nature. The study of hydrogen oxygen isotopes shows that, in the early stage of the deposit, magmatic water was dominant, and in the late stage, meteoric water was the dominant one. The authors thus hold that the Pb source of the deposit was related to the Guishan Formation Complex and the Laowan granite, and was close to the granite, showing its deep source characteristics. These results provide evidence for the magmatic origin of the ore-forming fluids.