桂东北珊瑚钨锡矿床地质特征及流体包裹体研究

珊瑚钨锡矿床是南岭成矿带西段桂东北地区一大型石英脉型钨锡多金属矿床,其大部分矿石中钨锡紧密共生。选取与锡相关的三个主成矿阶段(伟晶质、云母石英脉及石英脉)矿石中锡石流体包裹体,开展岩相学观察、显微测温和激光拉曼分析等测试工作。结果表明,伟晶质型锡石包裹体均一温度288~346℃,集中在310℃左右,盐度w(NaCl eq)4.65%~8.95%;云母石英脉型均一温度245~276℃,集中在270℃左右,盐度6.30%~8.55%;石英脉型均一温度235~343℃,集中在250℃左右,盐度4.65%~6.45%;总体而言,与锡矿化相关的流体为中高温、低盐度的NaCl-H₂O流体体系。研究认为,伟晶质阶段成矿流体温度相对较高,以气液相为主,密度较低,流体溶解度较大,其盐度分布范围较广;随着成矿流体的运移、冷却,至成矿中后期的云母石英脉、石英脉成矿阶段,流体的温度逐渐降低,成分以富液相为主,密度逐渐增大,溶解度降低,盐度分布趋于集中。

Geology and Fluid Inclusion of Shanhu Tungsten-Tin Deposit in Northeast Guangxi

Shanhu tungsten-tin deposit is a large-scale quartz vein type tungsten-tin polymetallic deposit in the northeast of Guangxi in the western part of Nanling metallogenic belt,tungsten and tin closely associated in most of the ores.In this paper,the cassiterite fluid inclusions in the ore of three main metallogenic stages(peritectic,mica quartz vein and quartz vein)related to tin were selected to carry out petrographic observation,microthermometry and laser Raman analysis.The results show that the homogenization temperature of pegmatite cassiterite inclusions ranges from 288 to 346℃,concentrated at 310℃,and the salinity is 4.65%~8.95%;the homogenization temperature of mica quartz vein type is 245~276℃,concentrated at 270℃,and the salinity is 6.30%~8.55%;the homogenization temperature of quartz vein type is 235~343℃,concentrated at 250℃,and the salinity is 4.65%~6.45%.Generally speaking,the fluid related to tin mineralization is NaCl-H2O with medium-high temperature and low salinity.The study shows that the temperature of ore-forming fluid is relatively high in pegmatite stage,mainly in gas-liquid phase,with low density and large fluid solubility,and its salinity distribution range is wide.With the migration and cooling of ore-forming fluid,the temperature of fluid gradually decreases,and the composition is mainly in liquid-rich phase.With the density gradually increasing and the solubility decreasing in mica quartz vein and quartz vein ore-forming stage in the middle and late stage of ore-forming,the distribution of salinity tends to be concentrated.