Rare Metal Distribution and Mineralization Potentiality of Pegmatites in Gabal El Fereyid Granite, South Eastern Desert, Egypt

Abstract

Gabal El Fereyid area, represents a promising area for monzogranite and pegmatites hosted rare-metal mineralization. Microscopically, monzogranite and pegmatites consist of K-feldspar, albite, and quartz with few biotite +/– hornblende. The radiometric studies of anomalous pegmatite samples show that their eU-contents reached up to 149 ppm while their eTh-contents reached up to 375 ppm, in contrast the eU and eTh contents of monzogranite range from 1 to 5.7 ppm and from 4.2 to 29.1 ppm, respectively. This indicates strong post-magmatic U-enrichment in the pegmatitic melt, due to the presence of radioactive minerals as thorite, uranothorite, fergusonite, samarskite and ishikawit. U and Th mineralization in pegmatites are discriminated as hydrothermal and magmatic types. Pegmatites show enrichment of large ion lithophile elements (LILE; Pb and Rb,), high field strength elements (HFSE; Y, Zr, Th, U, Nb and Ta) and rare earth elements but depleted in K, P, Sr, Cs, Ba and Ti. Pegmatites indicate moderate to large negative Eu anomaly and show clear W-type tetrad effect of the REE.