吉林靖宇小东大沟金矿床地球化学特征及成因探讨

小东大沟金矿床位于华北板块北缘东段王家店-天合兴多金属成矿带内,矿体的产出受断裂构造控制,与花岗斑岩、闪长岩等脉岩关系密切.流体包裹体研究表明,主成矿阶段成矿流体具有中低温(180~240℃)、低盐度(8%~11%)和低密度(0.92~0.98 g/cm~3)的特征.氢氧同位素分析结果显示,成矿流体主要来源为地幔初生水,后期混入大气降水.硫同位素分析结果显示,硫源为岩浆硫.结合区域地质背景和分析测试结果,认为小东大沟金矿床的形成与滨太平洋板块向欧亚大陆俯冲形成的陆缘岩浆弧活动有关,为中低温热液脉型金矿床.

GEOCHEMISTRY AND GENESIS OF THE XIAODONGDAGOU GOLD DEPOSIT IN JINGYU COUNTY,JILIN PROVINCE

The Xiaodongdagou gold deposit is located in the Wangjiadian-Tianhexing polymetallic metallogenic belt in the eastern section of northern margin of the North China plate, with orebodies controlled by fault structures. The mineralization is closely related to the dikes of granite porphyry and diorite. Study on fluid inclusion indicates that the ore-forming fluid in the main metallogenic stage is characterized by medium-low temperature (180-240℃), low salinity (8%-11%) and low density (0.92-0.98 g/cm³). The analysis result of hydrogen and oxygen isotopes shows that the ore-forming fluid is mainly from juvenile water in mantle mixed with later atmospheric precipitation. The sulfur is originated from magma based on sulfur isotope analysis. Considering the regional geological background and analysis results, it is believed that the Xiaodongdagou gold deposit of medium-low temperature hydrothermal vein type is the product of continental marginal magmatic arc activity formed by the subduction of the marginal Pacific Plate to Eurasia continent.