Study On Fluid Characteristics And Metallogenic Temperature And Pressure Conditions Of Renli Deposit In Mufushan Area

The Renli deposit is an ultra-large granitic pegmatite-type rare metal deposit newly discovered in China in recent years.It is one of the top ten geological prospecting achievements of the geological society of China in 2017.The Renli nb-ta deposit is located in the fault-uplift belt of the middle part of the neoproterozoic orogenic belt in the southeastern margin of the Yangtze plate and the transition area between the Yangtze plate and the cathaysia landmass.The nb-ta resources in vein 5 of Renli deposit account for 69%of the total resources of the ore section,and it is the pegmatite dike with the most complete zoning,the lowest degree of denudation and the largest scale.I experiment 5 series of ore deposits in the samples taken from the kernel,through the fluid inclusions microscopic methods of temperature measurement,lithium mica crystal experiment,ore deposit geological characteristics of combining previous research results,analysis of the geological features of ore-forming fluid,explore the kernel in the deposit ore-forming temperature pressure condition,to learn about other granite pegmatite type rare metal deposits has reference significance.The main conclusions of this paper are as follows:(1)Albitization occurs obviously in vein 5 of Renli deposit in microcline albite belt and Muscovite albite belt.From the lateral zone to the medial zone,lithium mica and fluorine-lithium mica gradually appear.The content of Li and F in crystalline medium increases,while the content of Cs in Muscovite decreases first and then increases,which is the result of late fluid action.In the core of lithium mica quartz,Nb-Ta minerals are mainly fine grained stone,no band,and coexist with recrystallized quartz,indicating that they have not undergone obvious changes in material composition and physical and chemical conditions,indicating their enrichment in the fluid phase.The mica-quartz mica type assemblage and the local enrichment of irregular disseminated tantalum-niobium ore reflect the hydrothermal characteristics.(2)Fluid inclusions in vein No.5 were captured during quartz recrystallization or lithium mica crystallization,and were samples of late Li,Na,F and Cl-rich ore-forming fluids.The homogenization temperature of inclusions ranges from 174.4 to 304.2~oC,and salinity ranges from 1.06 to 11.22%.The higher salinity fluid in Renli deposit is the Nb-Ta mineralization fluid occurring in the internal structural belt of vein 5 pegmatite.(3)The formation pressure of lithium mica quartz core is 310-450MPa and the temperature is 550-630~oC,showing a trend of decreasing crystal ization temperature with the decrease of pressure.The ore-forming temperature and pressure range is at the stable boundary of spodumene and lithium-permeable feldspar.Renli deposit has a certain potential for exploiting lithium-permeable feldspar resources.