Metallogenic mechanism and prospecting direction of Songshugang granite-type niobium-tantalum deposit in Jiangxi Province
The Songshugang granite-type Nb-Ta deposit is located in the Geyuan Town,Shangrao City,Jiangxi Province.It is not only the largest granite-type tantalum deposit in South China,but also a reservoir of Nb,Rb,Li,W,and Sn.The Songshugang granite consists of quartz-vein type tungsten-tin at the surface,and the granite-type niobium-tantalum deposit is deeply buried.The granite body displays vertical zonation,with topaz albite granite as the main body of granite in the deep,and in the vertical sequence of greisenization granite,K-feldspar granite and pegmatite.All the granite are featured by typical"snowball texture"with quartz and K-feldspar as phenocryst.The accessory minerals include columbite group minerals(columbite,tantalite and wodginite),zircons,cassiterites and ferberite.The in situ columbite U-Pb dating result reveals the mineralization age is ca.130Ma.Nb-Ta oxides are intergrowth with zircons and cassiterite,and display evident core to rim zonation,where the core is classified as columbite-(Fe)and the rim consists of tantalite and wodginite.This zonation records the whole suite has experienced magmatic to hydrothermal process.The zinnwaldite is the dominant micas in the Songshugang granite,with the Li2O varying from 2.89％to 4.29％.In the main topaz albite granite,both the large zinnwaldite(Znw1)and fine-grained zinnwaldite(Znw2)is present.The former Znw1 exhibits the zonation texture resulting from the variation of Rb contents.The Rb2O is 0.9％to 1.16％at the core while the rim sharply increases to 4.08％.Fine-grained zinnwaldite(Znw2)distribute in the matrix associated with albite,and contain the highest Ta(110 × 10-6).In the greisen,the radiation(or clusters)zinnwaldite(Znw3)is featured as the highest Sn content(464 × 10-6).The core-rim texture of zinnwaldite in granite records the magmatic fractionation process and the zinnwaldite in greisen is of hydrothermal origin.All the mineralogical textures show the Songshugang granite is highly evolved.The quartz veins-type W-Sn at the surface and"snowball texture"in the granite are the vital index for these highly evolved deposits.The Songshugang pluton is located close to the Lingshan complex,and we propose the margin of Lingshan complex is still a great target for rare metal prospecting in the further.
万方数据
维普
