小燕子沟金矿为近些年在川陕甘金三角地区发现的一处中小型金矿床,产在一大型韧性剪切带中,围岩为碧口群地层.矿体严格受断裂控制,按照矿石自然类型,可进一步划分为石英脉型与蚀变岩型.流体包裹体以气液二相包裹体为主,还有部分纯液相包裹体.显微测温结果显示,气液二相包裹体的均一温度峰值为180 ～ 300℃,盐度w(NaCl)峰值为2％～5％,密度峰值为0.80～0.95 g/cm3,具有中温、低盐度、低密度的特征.估算成矿压力为50 ～ 80 MPa,成矿深度约为5.5 ～7.5 km.据盐-温图成矿流体的盐度随着温度下降而升高,在180 ～220℃温度区间内,原始流体发生了减压沸腾,导致矿质卸载沉淀.%Xiaoyanzigou gold deposit occurring in a large ductile shear zone with its wall-rock of Bikou Group formation is a medium small gold deposit found in the golden triangle area of Sichuan, Shaanxi and Gansu Province in recent years. The ore body is strictly controlled by faults and,if classified by its natural type of ores,is quartz-vein type and altered rock type. Most of the fluid inclusions are gas-liquid inclusions and the rest are pure liquid inclusions. The ore-forming fluid is characterized by low salinity(2 % -5 % NaCl) ,low density (0.80 -0.95 g/cm3) and medium temperature (180 to 300 ℃). The estimated metallogenic pressure ranges from 50 MPa to 80 MPa and ore-forming depth from 5. 5 km to 7. 5 km. According to the salinity-temperature diagram, the salinity increases as the temperature goes down and the minerals discharge and precipitate while the primitive fluid boils at the temperature of 180 -220 ℃.
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