【摘要】 青海大场金矿床位于北巴颜喀拉造山带的中段,为区域印支造山过程晚期Au-Sb成矿作用的产物。该矿床为具有层控性和受断裂构造、隐伏岩浆活动控制的金矿床。矿体主要呈脉状、似脉状和透镜状赋存于三叠系巴颜喀拉群砂岩板岩互层组内,并严格受断裂破碎带的控制。大场金矿床先后经历了金、锑2期矿化,矿化平均成矿深度分别为5.9km和6.9km,锑矿化深度略浅于金矿化。成矿流体总体属中温、较低盐度、低密度的CO2-H2O-N2-H2S-CH4±CO±有机碳氢化合物体系。该矿床与造山型金矿具有相似的地质地球化学特征,其金矿化属造山型金矿的中成矿化,其锑矿化为造山型金矿的浅成矿化。更多还原

【Abstract】 The Dachang gold deposit is located in the North Bayan Har orogenic belt, an important metallogenic belt in Qinghai Province. The ore deposit was formed during the late stage of regional Indosinian orogenic process, with Au-Sb mineralization related closely to the evolution of the Bayan Har Ocean. All the gold ore bodies are hosted in Middle Triassic sandstone interbedded with slate of Bayan Har Mountains Group and controlled strictly by the fracture zone. All the ore bodies are in veined, veinlike and lenticular forms. Mineralization can be divided into two stages, namely, gold mineralization and antimony mineralization. The depth of gold mineralization and that of antimony mineralization are 6.9 km and 5.9 km, respectively, and the antimony mineralization is somewhat shallower than the gold mineralization. The ore-forming fluids belong to NaCl-H2O-CO2 type characterized by rich CO2, low-moderate temperature, low salinity, low density and strong reducibility. Geological and geochemical characteristics are similar to those of the standard orogenic deposits, gold mineralization is of the mesozonal orogenic type whereas antimony mineralization is of the epizonal orogenic type. Ore-forming fluids in the Dachang gold deposit were mainly derived from the formation water and mixed with a small amount of mantle source magmatic water and meteoric water. Fluid immiscibility and existence of organic matter play an important role in gold mineralizing processes. A geodynamic mineralized model can be concluded in the study.更多还原