Mineralogical Characteristics Of Scheelite And Mica In Zhuxi Super-Large Tungsten (Copper) Deposit In Northeastern Jiangxi Province

Zhuxi tungsten copper deposit in northeast Jiangxi province is the largest tungsten deposit discovered in the world in recent years.It belongs to taqian-Fuchun metallogenic subzone.The deposit has high grade,large scale and many orebodies.Scheelite is the main ore mineral in Zhuxi tungsten copper deposit.It is rich in rare earth elements and can be used to trace the genesis of the deposit effectively.Mica(including biotite and Muscovite)is widely distributed in the deposit.The chemical composition of mica is very sensitive to the physical and chemical states of the magmatic and hydrothermal fluids,which can effectively provide important information about the properties and sources of ore-forming fluids.In this paper,scheelite and mica of different types and genesis were studied,and micro-area in situ(EMPA and LA-ICP-MS)analysis was carried out to find out the distribution of elements in scheelite and mica of different types and generations,and to discuss the nature and evolution of ore-forming fluids.The main achievements of this paper are as follows:(1)Scheelite in Zhuxi deposit can be divided into early yunite dyke scheelite and skarn scheelite according to mineral symbiosis;Late quartz-sulfide scheelite and calcite veined scheelite.The early scheelite is enriched with LREE,the ree distribution curve is right-leaning,δEu is positive anomaly,and Mo element is enriched.The ree distribution curve of late scheelite is gentle,the fractionation of l REE is not obvious,δEu is weak negative anomaly,and Sr,Li and other elements are enriched at the same time.(2)Zhu Xi mica mineral deposits are mainly white mica and biotite,Muscovite and broken down into the magma stage white mica and hydrothermal white mica,magmatic period white mica to hydrothermal white mica,F content increased significantly,Rb,Cs,Sn and B content also increased,F and grouping points can increase W solubility in the fluid,promote the activation migration of tungsten;The biotite in Zhuxi deposit is mainly iron-rich biotite and magnesium-rich biotite,and the magnesium-rich biotite related to scheelite mineralization has higher Mg and F content and lower XMg content.(3)According to the elemental geochemical characteristics of scheelite and mica,the early fluid F content of Zhuxi deposit is low,and it is a reduction environment with low oxygen fugidity.However,the negative δEu value of scheelite in the late period is abnormal and the F content is gradually increased,indicating that the late fluid is rich in F and has high oxygen fugidity.The fluorine content in the ore-forming fluid affects the dissolution,migration and precipitation of tungsten,and the change of oxygen fugidity may be an important influencing factor for scheelite and sulfide precipitation mineralization in Zhuxi deposit.