Genesis And Prospecting Prediction Of Nb-Ta Rare Metal Granite Around Lingshan Pluton In North Jiangxi Province

Niobium and tantalum are important rare metal elements and strategic mineral resource,which have a wide range of applications in modern society and industry.Therefore,the mineralization genesis and exploration of niobium and tantalum ore are important tasks in recent years.South China is an important producing area of nonferrous metals and rare metal mineral(Nb-Ta)resources in China,in which the rare metals ores(niobium and tantalum)are mostly distributed in Cathaysia Block.The origin of the rare metals deposits(Nb-Ta),as previous revealed,are mainly related to the early Yanshanian peraluminous granites and mainly Ta-rich deposits.However,some Nb-rich rare metal(Nb-Ta)deposits were also found around Lingshan pluton in northeastern Jiangxi Province,southeastern margin of Yangtze Block.In this contribution,the geochemical data of river sediments and natural heavy mineral in the Lingshan pluton and its surrounding areas,as well as the deposit data of main niobium and tantalum deposits(Songshugang Nb-Ta ore and Huangshan Nb-Ta ore),are systematically collected.Based on detailed geochronological and geochemical analysis for the Lingshan granites,the following main results have been achieved:1.The results of LA-ICPMS zircon U-Pb dating show that the main biotite granitic facies of the Lingshan pluton was formed in the early Cretaceous(132 ±0.4).This age is consistent with the previous reported intermediate lithofacies age(? 132Ma)and the ore mineral(niobium-tantalite)U-Pb age(130Ma),which further indicates that the Lingshan pluton is closely related to rare metal mineralization.2.The results of mineralogical and petrogeochemical analysis show that the mineral assemblages of magmatic crystallization differentiation in Lingshan pluton are mainly plagioclase and accessory minerals such as rutile and sphene,but lack of potash feldspar and mica minerals,and have high Ga/Al ratio(> 2.6)and high Zr+Nb+Ce+Y content(388-1016ppm),indicating the characteristics of A1-type granite.The rare metal mineralized granites related to most of the S-type granites in South China are quite different,which may be the main reason why the rare metal deposits related to the Lingshan rock body are relatively rich in Nb and poor in Ta.3.The metallogenic model of rare metal(niobium and tantalum)deposits around Lingshan rock body is preliminarily established.combined with the comprehensive geochemical anomaly map of stream sediments and natural heavy sand in Lingshan rock body and its surrounding area,it is revealed that there are several superposition areas of stream sediment Nb-Y-Sn-W anomalies and natural heavy sand Nb-Ta mineral anomalies related to the mineralization of rare metal niobium-tantalum deposits around Lingshan rock body.It indicates that the development area of pegmatite veins in the related anomaly zone is an important prospect area for prospecting rare metal (niobium and tantalum) deposits.