江西黄沙石英脉型钨矿床流体包裹体研究

Fluid inclusion studies of the Huangsha quartz-vein type tungsten deposit,Jiangxi Province

黄沙钨矿床是赣南地区一大型石英脉型钨多金属矿床。本文采用"流体包裹体组合"的研究方法,对黄沙钨矿床主成矿阶段早期的黑钨矿-石英脉和晚期的硫化物-(黑钨矿)-石英脉石英中的流体包裹体进行了显微测温和拉曼探针的分析。研究表明,黑钨矿-石英脉中包裹体主要为水溶液包裹体和含CO2水溶液包裹体,硫化物-(黑钨矿)-石英脉中主要发育水溶液包裹体。黑钨矿-石英脉中包裹体的均一温度明显高于硫化物-(黑钨矿)-石英脉中的包裹体,但两者水溶液包裹体的盐度相差不大。激光拉曼探针测试表明,两期矿脉中水溶液包裹体的组分主要为水,在黑钨矿-石英脉中的含CO2水溶液包裹体,除CO2外,还检测到CH4和N2组分。研究表明,以CO2逸失为特征的流体不混溶作用是早期黑钨矿-石英脉含矿流体中的金属络合物分解并沉淀成矿的主要机制,晚期硫化物-(黑钨矿)-石英脉中矿质的沉淀则主要是流体的混合作用导致。

The Huangsha tungsten deposit is an important large quartz-vein type W-polymetallic deposit in southern Jiangxi Province.Based on detailed petrographic observations and using the means of Fluid Inclusion Assemblage（FIA）,we carried out microthermometric and Raman microspectroscopic studies of fluid inclusions in early wolframite-quartz veins and late sulfide-（wolframite）-quartz veins of the main ore-forming stage of Huangsha tungsten deposit.The fluid inclusions are mainly aqueous inclusions and carbon-aqueous inclusions in wolframite-quartz veins and only aqueous inclusions in sulfide-（wolframite）-quartz veins. Experimental results show that the aqueous inclusions decrease in homogenization temperature from the early veins to the late veins at constant salinity.Raman microspectroscopic studies of the fluid inclusions show that,the main component of aqueous inclusions in wolframite-quartz veins and sulfide-（wolframite）-quartz veins is H 2 O,whereas those in wolframite-quartz veins are major H 2 O,minor CO2,and rare CH 4 and N2.The characteristics of fluid inclusions in the Huangsha tungsten deposit indicate that the fluid immiscibility caused by CO2 escaping possibly led to metals precipitation in the wolframite-quartz veins and the fluid mixing led to metals precipitation in the wolframite-quartz veins.