THE ROLE OF EXTREME FRACTIONATION IN THE FORMATION OF RARE METALS: A CASE STUDY FROM GABAL DARA GRANITE AND CO-GENETIC PEGMATITES, NORTH EASTERN DESERT, EGYPT | ||||
| Annals of the Geological Survey of Egypt | ||||
| Volume 39, Issue 39, 2022, Page 43-56 PDF (1.87 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/asge.2022.321083 | ||||
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| Author | ||||
A. A. Abdel Hamid 
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| Nuclear Materials Authority, Cairo, Egypt | ||||
| Abstract | ||||
| The granite of Gabal Dara, North Eastern Desert of Egypt, grades to the pegmatites along its boundaries, which are ranging from small pockets to large bodies with lenticular and irregular shapes in the concerned granite. Among them, three main pegmatite bodies display different degrees of enrichment in Zr, Nb, Th, U and REEs. The rare-metal mineralization is essentially composed of zircon and ishikawaite, while uranothorite and allanite-Ce are recorded as inclusions in them. A geochemical comparison among the Gabal Dara granite, barren and mineralized pegmatites indicated that they are exhibiting similar geochemical signatures; however, the mineralized pegmatites are more fractionated than the investigated granite. The Gabal Dara granite and pegmatites are highly fractionated rocks with pronounced alkaline affinity and extensive fractional crystallization. Extreme fractionation from granite to pegmatites is leading to the accumulation of the rare metals in some parts of the highly evolved pegmatites. | ||||
| Keywords | ||||
| Fractionation; Rare Elements; Gabal Dara Granite; Pegmatites; Alkaline Affinity | ||||
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