藏南泽当努日铜钨钼矿床流体地球化学特征及矿床成因研究

Fluid Geochemical Characteristics and Genesis of Skarn-porphyry Copper-Tungsten-Molybdenum Polymetallic Deposit in Nuri,Zedang,Southern Tibet

努日铜钨钼矿床作为大型矽卡岩型矿床,整个矿化过程可划分为5个成矿阶段,分别为早期矽卡岩阶段、矽卡岩退化蚀变阶段、氧化物阶段、石英-硫化物阶段及石英-碳酸盐阶段,其中氧化物阶段及石英-硫化物阶段分别是矿区内最主要的矿化阶段。研究发现氧化物阶段及石英-硫化物阶段共发育4种类型的流体包裹体,分别为富液相的气液两相包裹体、含子晶的多相包裹体、富CO_(2)的富气相包裹体、单相包裹体。由于显微镜下4种或2种以上类型的包裹体常在同一石英颗粒中共生,且不同类型的包裹体具有相近的均一温度,又结合气相成分协变图,说明成矿流体在主成矿阶段发生了沸腾作用,为其硫化物沉淀的主要因素。

As a large skarn type deposit,the whole mineralization process can be divided into five mineralization stages,including early skarn stage,skarn degradation and alteration stage,oxide stage,quartz-sulfide stage and quartz-carbonate stage,among which the oxide stage and quartz-sulfide stage are the most important mineralization stages in the mining area.Four types of fluid inclusions are developed in the oxide stage and quartz-sulfide stage,namely,liquid-rich gas-liquid two-phase inclusions,polymorphic inclusions containing daughter crystals,CO_(2)-rich gas-phase inclusions and single-phase inclusions.Petrographic observations show that more than four or two types of inclusions often co-exist in the same quartz particle,and different types of inclusions have similar homogenization temperatures.Combined with the covariance of gas compositions,indicating that the boiling of ore-forming fluid occurred in the main ore-forming stage,which is the main factor of sulfide precipitation.