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合仁坪金矿床位于湘西柳林汊金矿带,是典型的钠长石-石英脉型金矿床,本文对其进行了较系统的成矿流体地球化学研究。结果表明,与成矿有关的石英和方解石中的流体包裹体主要为气液两相包裹体。石英中包裹体的均一温度范围为111~375℃,盐度为0.18%~7.86%的NaCl;方解石中包裹体的均一温度范围为196~271℃,盐度为4.18%~6.74%的NaCl;成矿溶液的密度为0.633~0.997g/cm~3,表明该矿床的成矿流体均属于中低温、低盐度和低密度的流体;成矿压力为4~209MPa,成矿深度约为1.2~6.8km,该矿床是在中低压力、中浅成条件下形成的。激光拉曼探针分析表明,包裹体中的气相成分有CO_2、CO、CH_4和N_2,液相成分为H_2O和CO_3~(2-),指示含有机质的沉积物变质脱水可能是成矿流体来源的方式。对石英和钠长石氢氧同位素研究表明,该矿成矿流体的δ~(18)O_(H_2O)值为7.1‰~10.8‰,δD_(H_2O)值介于-69‰~-55‰,合仁坪金矿的成矿流体主要来源于变质水。
The Hepingping gold deposit is a typical albite-quartz vein type gold deposit located in the Liulinghu gold belt of western Hunan Province. In this paper, we systematically studied the ore-forming fluid geochemistry. The results show that the fluid inclusions in quartz and calcite related to metallogenesis are mainly gas-liquid two-phase inclusions. The homogenization temperature range of inclusions in quartz is 111 ~ 375 ℃ and the salinity is 0.18% ~ 7.86% NaCl. The homogenization temperature of inclusions in calcite is 196 ~ 271 ℃ and the salinity is 4.18% ~ 6.74% NaCl. The density of ore-forming solution is 0.633 ~ 0.997g / cm ~ 3, indicating that the ore-forming fluids of this deposit all belong to medium- low temperature, low salinity and low density fluids. The metallogenetic pressure is 4 ~ 209MPa and the metallogenic depth is about 1.2 ~ 6.8km, the deposit is formed under medium-low pressure and moderate to moderate conditions. Laser Raman probe analysis showed that the gas components in the inclusions are CO_2, CO, CH_4 and N_2, and the liquid components are H_2O and CO_3 ~ (2-), indicating that the metamorphic dehydration of sediments may be the source of ore-forming fluid The way. The study of hydrogen and oxygen isotopes of quartz and albite shows that the δ 18 O_ (H_2O) value of the ore-forming fluid is 7.1 ‰ ~ 10.8 ‰ and the δD_ (H_2O) value ranges from -69 ‰ to -55 ‰, The ore-forming fluid of Hepingping gold mine mainly comes from metamorphic water.