滇西李子坪-富隆厂铅锌银矿床矿物化学研究及其成矿指示意义

Study on Mineral Chemistry of Liziping-Fulongchang Pb-Zn-Ag Deposit in Western Yunnan and Its Metallogenic Significance

通过光学显微镜、粉晶X射线衍射分析仪(XRD)、场发射扫描电子显微镜(FESEM)、电子探针(EPMA)等方法查明了李子坪和富隆厂铅锌银矿床的矿物组成和矿物化学成分。研究表明:李子坪矿床的硫化物/硫盐矿物主要有闪锌矿、细硫砷铅锌、方铅矿、含砷黄铁矿;富隆厂矿床的硫化物/硫盐矿物主要有闪锌矿、方铅矿、灰硫砷铅锌、黄铁矿。矿物化学特征指示两矿床经历了含Pb-Zn成矿流体对富As黄铁矿角砾的交代,As元素的活化;闪锌矿、方铅矿沉淀;富As、(Sb、Cu)残余流体对方铅矿的交代形成硫盐的过程。各矿段硫盐类型的差异由成矿流体组分和物理化学条件的共同控制。针对富含As、Sb元素的特殊型沉积岩容矿铅锌银成矿体系开展的矿物学和矿物化学研究,有助于促进类似矿床成矿作用的理论认识。

The mineral composition and mineral chemical composition of Liziping and Fulongchang lead-zinc-silver deposits have been ascertained in detail by means of optical microscopy,XRD,FESEM and EMPA.The mineralo-gical study shows that the sulfide/sulfosalt minerals in Liziping deposit mainly include sphalerite,gratonite,galena,arsenic-bearing pyrite.The sulfide/sulfosalt minerals in the Fulongchang deposit mainly include sphalerite,galena,jordanite and pyrite.The mineral chemical characteristics indicate that the two deposits have undergone metasomatism and activation of As elements by Pb-Zn ore-forming fluids to As-rich pyrite breccia;precipitation of sphale-rite and galena;the process of formation of sulfosalts by replacement of galena by As-(Sb,Cu)rich residual fluids.The difference of sulfur salt type in each ore section is controlled by ore-forming fluid composition and physicochemical conditions.In this paper,the mineralogy and mineral chemistry of the ore-bearing Pb-Zn-Ag metalloge-nic system of sediment-hosted rich in As and Sb elements will help to promote the theoretical understanding of mineralization of similar deposits.