辽宁东五家子金矿床流体包裹体特征研究

辽宁东五家子金矿床产于太古代变质岩内断裂构造之中,矿脉严格受NW向断裂构造控制。对矿石中的流体包裹体进行了岩相学和显微测温研究。结果表明:矿石石英中流体包裹体发育,主要发育气液二相和少量单液相包裹体两种类型,成矿流体为H2O-NaCl体系;并具有低盐度(7.59%～10.87%)、低密度(0.94～0.98 g/cm3)的特点;成矿温度为151.4～201.3℃,成矿最低压力为14.3～21.0 MPa,成矿最低深度为1.43～2.10 km。结合矿石黄铁矿样品中硫同位素分析结果,其变化范围较窄,为1.91‰～2.54‰,平均值为2.24‰,均一化程度较高,接近陨石硫。分析认为,成矿物质可能来自深部(上地幔),含矿热液在上升过程中不断汇聚于一定的断裂构造空间,因降温、减压而导致成矿物质沉淀富集成矿,最终确定矿床成因类型是受断裂构造控制的低温热液脉状金矿床。

Study on characteristics of fluid inclusions in Dongwujiazi gold deposit, Liaoning

Dongwujiazi gold deposit in Liaoning Province occurs in a fauh structure in Archean metamorphic rock series, the veins of which are strictly controlled by a fault structure trending NW. The petrography and microthermom- etry of fluid inclusions in ores were studied. The results show ttlat fluid inclusions are well developed in quartz, that the fluid inclusions primarily include two types, namely gas-liquid two-phase and liquid one-phase fluid inclusions, and that the ore-forming fluid belongs to H2O-NaCl system; The fluid inclusions have characteristics of low salinity （7.59 % - 10.87 % ）and low density（0. 94 -0.98 g/cm^3 ） ; The ore-forming temperature is 151.4 -201.3 ℃ ,the minimum metailogenic pressure is 14. 3 -21. 0 MPa, and the minimum mineralization depth is about 1.43 - 2.10 km. Combining with the analysis results about the sulfur isotope of pyrite in ores, the value of sulfur isotope has a narrow variation range, just between 1. 91‰ - 2.54 ‰ and the average value is 2.24 ‰ which stands tor a relatively high degree of homogenization, close to the aerolite sulfur composition. It is thought after comprehensive analysis that metallogenic materials mainly derived from deep source （upper mantle） and the ore-bearing hydrothermal solutions continuously accumulate in specific fault structure area during ascending process. They precipitated and enriched into deposits as a result of temperature decrease and pressure drawdown. Finally we conclude that the genetic type of Donwujiazi gold deposit is vein-type low temperature hydrothermal gold deposit controlled by fault structures.