Rare metals bearing pegmatites in the Nubian Shield: A case study of Ras Al-Baroud area, Eastern Desert of Egypt

Document Type : Original papers

Authors

1 Geology Department, Faculty of Science, New Valley University, 72511 El-Kharga, Egypt

2 Geological Sciences Department, National Research Centre, 12622 Dokki, Cairo, Egypt

Abstract

Abstract
This study documents the geochemical evolution of rare-metal mineralized granitic pegmatite of Ras Al-Baroud using mineral chemistry and whole rock chemistry. Pegmatite occurs as sheet-like bodies, pockets along the edges of the Ras Al-Baroud post-collisional granite, or within fault zones. Pegmatites at the outer margins of Ras Al-Baroud granites show gradational boundaries. In a few outcrops, the Ras Al-Baroud pegmatites are affected by intense metasomatic-hydrothermal alteration resulting in albitization and greisenization: especially close to the contact with the host rocks. Nb-Ta oxides are the most important rare metals in the Ras Al-Baroud pegmatite and are represented mainly by columbite and less amount of tantalite. They are commonly zoned, exhibiting a wide range of chemical compositions and are characterized by partial digestion and late-stage overgrowth due to the effecting of magmatic and hydrothermal processes in the granite-pegmatite system. Ras Al-Baroud pegmatite is considered to mainly crystallize late from a pegmatite-forming melt that resulted from a combination of magmatic and hydrothermal processes. Extended fractional crystallization in Ras Al-Baroud granites eventually produced saturated, late-magmatic magmatic fluids. These fluids migrated towards the apex of the magma chamber, reacting with still-hot but subsolidus granite and becoming increasingly focused into distinct channels and veins. This upward and outward mode of fluid migration led to pegmatites with gradational boundaries.

Keywords

Main Subjects

Files

Share

How to cite

Statistics