吉林磐石粗榆金矿床流体包裹体特征及矿床成因

粗榆金矿床大地构造位置位于华北克拉通北缘东段,主要容矿围岩为花岗岩、石英闪长岩及花岗闪长岩;控、容矿构造以区内NW向断裂为主。重点对不同阶段石英流体包裹体进行了包裹体岩相学、显微测温学和激光拉曼显微探针研究。成矿流体包裹体可分为气液二相包裹体和含CO2包裹体。气液二相包裹体成矿流体盐度为1.73%~11.23%,密度0.71~0.88 g/cm3,均一温度为233.1~304.4℃;含CO2包裹体成矿流体盐度为7.64%~10.87%,密度0.54~0.92 g/cm3,均一温度为268.9~340.4℃。激光拉曼光谱分析表明,流体气相成分主要为CO2和H2O。稳定同位素研究结果表明,矿床成矿热液来源为幔源C-H-O流体分异之后的岩浆热液。通过等容线图解法估算成矿压力为95~135 MPa,成矿深度为8.02~9.69 km。结合粗榆金矿床的地质特征,认为粗榆金矿床的成矿类型为中成造山型金矿床。

Characteristics of fluid inclusions and genesis of Cuyu Gold Deposit,Jilin Province

Cuyu Gold Deposit is located in the east section of the north margin of North China Craton. The major ore-hosting rocks are granite, quartz diorite and granodiorite, while the NW-trending faults are major ore-bearing structures in the mine area. Petrographic, microthermometric and laser Raman spectroscopic studies on fluid inclusions have been given in this paper. The results show that fluid inclusions in quartz crystals can be classified into aqueous two- phase and CO2-bearing three-phase inclusions. Salinities of aqueous two-phase inclusions range from 1.73 % to 11.23 % ,densities range from 0.71 g/cm3 to 0.88 g/cm3 ,and homogenization temperatures range from 233.1 ℃ to 304.4 ℃. Salinities of CO2-bearing three-phase inclusions range from 7.64 % to 10.87 %, densities range from 0.54 g/cm3 to 0.92 g/cm3 , and homogenization temperatures range from 268.9 ℃ to 340.4 %. Laser Raman spectroscopy of inclusions indicate that the principal gas-phase components are H20 and CO2. The stable isotope analysis results show that the metallogenic fluid originates from the magmatic hydrothermal fluids after the differentiation of mantle-derived C-H-O fluids. According to the diagram of isochore, the ore-forming pressure is estimated to be 95 MPa to 135 MPa, and the estimated ore-forming depth ranges from 8.02 km to 9.69 km. On the basis of the geological char-acteristics,the genetic type of Cuyu Gold Deposit is defined as orogenic gold deposit.