山东金岭埠南金矿床流体包裹体特征及成因探讨

Discussion about characteristics and genesis of fluid inclusions in Bunan Gold Deposit in Jinling,Shandong

埠南金矿床位于胶莱胶北断隆北缘,招（远）—莱（州）成矿带中部,受NE向灵山沟—北截主断裂以及一系列次级构造控制。金矿体赋存于NE向构造中,并受其控制,矿石类型以蚀变岩型为主。通过对埠南金矿床不同成矿阶段的流体包裹体进行岩相学、显微测温、单个包裹体激光拉曼分析,结果表明：石英中流体包裹体主要有Ⅰ型气液二相包裹体和Ⅱ型含CO2三相包裹体,成矿流体均一温度为280~320℃,盐度为3.76%~12.99%;流体为Na Cl-H2O-CO2体系,含少量的CH4和N2。通过等容相交法,得出包裹体捕获压力为54~106 MPa,并估算出成矿深度介于5.87~8.52 km。流体H、O同位素特征表明,成矿流体以地幔流体为主,同时存在岩浆水和大气降水的参与。综合分析认为,埠南金矿床属于蚀变岩型中成造山型金矿床。

Bunan Gold Deposit is located in the northern edge of Jiaolai- Jiaobei uplift and the middle of Zhaoyuan- Laizhou metallogenic belt,controlled by the NE trending Lingshangou- Beijie main fault and a series of secondary ore-controlling structures. The gold orebodies are hosted in NE trending structures and controlled by them.The ores are mainly alteration rocks. The petrography and microthermometry of the fluid inclusions in different metallogenic stages of Bunan Gold Deposit are studied,and Raman laser analysis of individual inclusion is carried out. The result shows that the fluid inclusions in quartz mainly include Ⅰ type gas-liquid two-phase inclusion and Ⅱ type CO2-containing three-phase inclusion; the homogenous temperature of the ore-forming fluids is 280 ℃ to 320 ℃ and the salinity is 3. 76 % to 12. 99 %; the fluids belong to a Na Cl- H2O- CO2 system which contains small amount of CH4 and N2. Isochore intersection reveals that the inclusion-capturing pressure of is 54 MPa to 106 MPa and the estimated ore-forming depth is between 5. 87 km and 8. 52 km. The characteristics of H and O isotopes in fluids indicate that the ore-forming fluids are mainly mantle fluids and contain magmatic water and precipitation. The paper summarizes that Bunan Gold Deposit is a alteration rock type medium-depth orogenic gold deposit.