辽宁省开封沟金矿流体特征、锆石U-Pb年龄及矿床成因研究

辽宁清原开封沟金矿床位于华北克拉通北缘清原花岗-绿岩地体内，矿体为石英脉型，控矿构造为北东东向浑河断裂及其次级断裂.流体包裹体有气液两相、含CO₂三相和纯CO₂包裹体3种类型.气相成分以CO₂为主.流体包裹体盐度较低，介于0.35%~19.55%（Nacl质量分数）之间，平均为6.55%.均一温度介于110~390℃之间，平均247℃，属于中温热液矿床.开封沟金矿成矿压力估算为26~91 MPa，平均61 MPa；成矿深度为2.7~8.2 km，平均5.7 km.成矿早阶段流体为富CO₂的高温流体.主成矿阶段富CO₂型和气液两相流体包裹体共存，发生了以CO₂逸失为特征的不混溶或沸腾.成矿晚阶段主要为气液两相包裹体.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.与成矿密切相关的花岗斑岩体锆石U-Pb年龄为200.1±1.5 Ma，7个点的加权平均年龄为200.2±0.84 Ma，形成于燕山早期.成矿综合研究表明，开封沟金矿床成因类型属造山型金矿.

FLUID INCLUSION, ZIRCON U-Pb AGE AND GENESIS OF THE KAIFENGGOU GOLD DEPOSIT IN LIAONING PROVINCE

The quartz vein type of Kaifenggou gold deposit in Liaoning Province is situated in the Qingyuan granitegreenstone terrain of North China Craton.The NEE-trending Hunhe fault and its secondary faults in the area are the main ore-controlling structures.The fluid inclusions in quartz crystals can be classified into gas-liquid two-phase,CO2-bearing three-phase and pure CO2 types.The bubbles（gas-phase）are dominated by CO2.The salinities range from 0.35% to 19.55%（NaCl）,with an average of 6.55%.The homogenization temperatures range from 110℃ to 390℃,averagely 247℃,suggesting a mesothermal deposit.The ore-forming pressures of the deposit range from 26 to 91 MPa,with an average of 61 MPa,corresponding to depths of 2.7 to 8.2 km,averagely 5.7 km.In the early mineralization stage,the fluid inclusions are characterized by low salinity,high-temperature and rich CO2.In the major mineralizing stage,the CO2-rich fluid inclusions and gas-liquid two-phase inclusions coexist.Because of the immiscibility or boiling characterized by CO2 escaping,the salinity increases in the residual fluid.Fluid inclusions in the later mineralization stage are of gas-liquid two-phase.The stable isotope analyzing results show that the metallogenic fluid is originated from the magmatic hydrotherm after the differentiation of mantle-derived C-H-O fluid.The granite porphyry closely related to mineralization has a zircon U-Pb age of 200.1 ± 1.5 Ma,with seven zircon concordia age of 200.2 ± 0.84 Ma,showing that the deposit was formed in early Yanshanian period.Comprehensive studies suggest that the Kaifenggou gold deposit belongs to orogenic type.