广西大瑶山大黎铅锌矿床成因研究--流体包裹体以及氢氧硫同位素的制约

Study of Dali Pb-Zn deposit genesis in Dayaoshan area,Guangxi:the restriction of fluid inclusion and H-O-S isotopic data analysis

大黎铅锌矿是近年来大瑶山新发现的矿床,位于南华准地台桂中—桂东台陷区大瑶山金矿带,矿体受断裂构造控制,赋存于次级断裂破碎带中,呈脉状、透镜状,其物质来源及成因尚存分歧。依据脉体穿插关系及矿物组合将成矿作用分为石英-黄铁矿阶段、石英-黄铁矿-黄铜矿-磁黄铁矿阶段、石英-铅锌多金属硫化物阶段、石英-黄铁矿-碳酸盐四个阶段。流体包裹体显微测温和激光拉曼光谱分析表明,成矿流体具有中低温、低盐度、低密度的特征,主成矿阶段为含CH4的NaCl-H2O体系,与中低温热液成矿流体特征相似。氢、氧同位素分析表明初始成矿流体为岩浆水,后期叠加变质水。铅锌矿石硫同位素显示,主成矿期硫同位素具有典型岩浆硫特征,推测大部分铅锌成矿物质来源以深部岩浆为主。初步认为大黎铅锌矿床属于断裂控制的中低温热液脉型铅锌矿。

Dali Pb-Zn deposit is newly discovered in the Dayaoshan gold belt of Central-East Guangxi platformal depression area of South China sub-platform.The orebody is controlled by the fault structure and hosted in the secondary fracture belt as veins and lens.The metallegenic material source and deposit genesis are still controvertial.On the basis of the interpenetrating relationship of vein body and mineral combination,the mineralization process is divided into four stages,quartz-pyrite stage,quartz-pyrite-chalcopyrite-pyrrhotite stage,quartz-polymetallic sulfide stage and quartz-pyrite-calcite stage.Microscopic temperature measurement and Laser Raman spectroscopy analysis of the fluid inclusion indicates that the ore forming fluid of Dali Pb-Zn deposit is characterized of middle-low temperature,low salinity and low density.In the main metallogenic stage,there is NaCl-H2O system containing CH4,which is similar to the low temperature hydrothermal ore-forming fluid.Hydrogen and oxygen isotopic composition of the fluid inclusion indicates that the initial ore-forming fluid is magmatic water,and metamorphic water is superimposed in the later stage.The sulfur isotopic composition of lead-zinc ores shows that the sulfur isotopes in the main ore-forming period have the typical magma sulfur characteristics,and it is speculated that most of the lead-zinc ore-forming materials are mainly from the deep magma.It is preliminarily considered that Dali lead-zinc deposit is a medium-low temperature hydrothermal vein type lead-zinc deposit controlled by the fault structure.