对内蒙古阿拉善西部碱泉子金矿床的石英流体包裹体进行了岩相学和显微测温分析,并分析了石英流体包裹体的氢、氧同位素组成。研究结果表明,石英中流体包裹体发育程度不太好,且粒度偏小,包裹体大小多为2.0~8.0μm,包裹体类型有气液二相盐水溶液包裹体(Ⅰ型)和含CO2三相包裹体(Ⅱ型),且以前者为主。包裹体均一温度为182.5~308.6℃,平均249.1℃;盐度为2.07%~9.21%,平均6.03%;成矿流体的密度为0.65~0.93g/cm3,属于中温低盐度低密度范畴;压力平均值为21.86MPa,对应的成矿深度平均值为2.19km,属于中浅深度范畴。成矿流体主要来源于变质水和岩浆水,并有少量大气降水的参与。水-岩反应、温度和压力的降低可能是导致碱泉子金矿金在容矿空间中卸载并富集成矿的主要原因。
In this study,petro facies,micro-thermometry,hydrogen and oxygen isotopics,and fluid inclusions in quartz from the Jianquanzi gold deposit,Alashan,Inner Mongolia,China were studied.The results showed that fluid inclusions in quartz were small in size,mostly ranging from 2 to 8 μm.These inclusions consisted of gas and liquid phases (type Ⅰ) as well as gas,liquid and CO2 phases (typeⅡ) .Homogenization temperatures,salinities and densities of the fluid inclusions ranged from 182.5 to 308.6℃ (averaging 295℃ ) ,2.07% to 9.21% (averaging 6.03% ) and 0.74 to 0.93 g /cm3,respectively.Based on the average ore-forming pressure which is 218.6 × 105Pa,the estimated average ore-forming depth pressure is 2.186 km,belonging to the shallow to medium depth type.The ore-forming fluid seems to be a mixture of magmatic and metamorphic waters mixing with meteoric water.Fluid-wallrock interaction,along with the decreasing of temperature and pressure,possibly induced gold to concentrate and deposite within the shear zone.