黔东南石英脉型金矿床中铁白云石流体包裹体研究

铁白云石是黔东南石英脉型金矿主成矿阶段的主要脉石矿物之一,与金的矿化关系十分密切,在金的运移、沉淀等方面起着重要作用,其流体包裹体特征可以反映成矿流体性质。通过对铁白云石开展系统的流体包裹体岩相学观察、均一法测温和冰点测定,计算出包裹体盐度和密度等数据。结果表明: 铁白云石包裹体较为发育,以含CO₂的包裹体为主; 均一温度集中在240~300 ℃范围内,平均均一温度为267.21 ℃; 成矿流体的盐度为7.31%~21.40%(NaCl),平均为15.31%(NaCl); 成矿流体的密度介于0.72~0.97 g/cm³之间,平均为0.89 g/cm³。认为黔东南石英脉型金矿床属于低盐度、高密度的中温热液矿床。

A study on fluid inclusions within ankerites of quartz-vein gold deposits in southeastern Guizhou

Ankerite is one of the main gangue minerals at main mineralization stage of quartz-vein gold deposits in southeastern Guizhou. It plays an important role in the migration and precipitation of gold and the characteristics of fluid inclusions within ankerite can reflect the ore-forming fluid character. The authors conducted experiments on the microscopic petrography observation, homogenization temperature and freezing point of fluid inclusions, and then calculated the inclusions salinity and density. Results show CO₂ inclusions in ankerite are well developed; ore-forming fluid uniformity temperatures concentrate in 240-300 ℃ with average of 267.21 ℃, the salinity of ore-forming fluid is between 1.57%-12.96% (NaCl) with average of 15.31%(NaCl); and the mineralization density distribution ranges from 0.69 g/cm³ to 0.91 g/cm³, with average of 0.89 g/cm³. So the quartz-vein gold deposits of southeastern Guizhou are middle temperature hydrothermal deposits and the ore-forming fluid has the characteristics of high density and low salinity.