广西大明山地区六梨钨矿流体包裹体特征与成矿机制

Characteristics of Fluid Inclusion and Metalogenic Mechanism of Liuli Tungsten Deposit of Damingshan Region,Guangxi

广西大明山地区六梨钨矿找矿潜力大,本文通过矿体、矿石特征和流体包裹体分析,探究其成矿机制。钨矿体受断裂控制,矿石类型主要为石英网脉状钨矿石,偶见云英岩型钨矿石。成矿期可大致分为两个阶段:早阶段为辉钼矿—云英岩阶段,晚阶段为白钨矿—石英阶段。石英中流体包裹体以水溶液流体包裹体(W型)为主,偶见CO_(2)-H_(2)O流体包裹体(C型)和纯气相流体包裹体(PC型);流体均一温度为140~382℃,平均263℃;盐度0.18wt%~12.68wt%NaCl,平均4.83wt%NaCl;密度为0.62~0.98 g/cm^(3)。包裹体气相主要成分为CO_(2)、H_(2)O,均为低峰值,结合闪锌矿-黄铜矿固溶体分离温度,成矿流体为低盐度、中高温、低CO_(2)流体,属于H_(2)O-CO_(2)-NaCl体系。白钨矿—石英阶段(晚阶段)是本矿床的主成矿阶段,六梨钨矿从成矿早阶段到晚阶段的平均均一温度具有降低的趋势,均一温度降低是成矿的主要机制。

The Liuli tungsten deposit in Guangxi Province shows great prospecting potential,and this paper studies the mineralization mechanism based on the characteristics of ore body,ore rocks and fluid inclusions.The tungsten ore body is controlled by fractures,and the ore type is mainly quartz vein tungsten ore with occasionally greisen tungsten ore.The ore-forming process could be roughly divided into two stages.The early stage is the molybdenite-greisen stage,and the late stage is the scheelite-quartz stage.The fluid inclusions in quartz mainly consist of aqueous solution(W type),very little CO_(2)-H_(2)O(C type)and pure gas(PC type).The homogenization temperatures of the fluid are within the range of 140~382℃,with an average of 263℃,and the salinities are within the range of 0.18~12.68wt.%NaCl,with an average of 4.83wt.%NaCl,and the densities are within the range of 0.62~0.98 g/cm^(3),and the main components of gases are CO_(2) and H_(2)O with low peak values.Fluid inclusion data combined with the phase separation temperature of sphalerite-chalcopyrite solid solution show that the mineralizing fluid should be characterized by low-salinity,medium-high temperature and CO_(2)-depletion,and could be defined as H_(2)O-CO_(2)-NaCl system.The scheelite-quartz stage(late stage)is the main mineralizing stage of this deposit and the average homogenization temperatures from the early stage to and the late stages of the Liuli tungsten deposit shows a decreasing trend,hence this decrease in homogenization temperature could be the main mineralizing mechanism.