Magmatic and hydrothermal evolution of highly-fractionated rare-metal granites at Gabal Nuweibi, Eastern Desert, Egypt

The Nuweibi intrusion was emplaced during the final tectono-magmatic stage of Arabian-Nubian Shield development (ANS). Two cogenetic phases can be recognized in field: early phase is represented by porphyritic albite granite and non-porphyritic granite. Mineralogically, both are essentially composed albite, quartz, K-feldspars with subordinate muscovite. Accessory minerals include fluorite, zircon, NbTa oxides, cassiterite, beryl, topaz, garnet. Geochemically, consists extensively fractionated rare-metal low contents TiO2, FeOt, CaO, MgO, P2O5, Sr, Ba contrast to elevated concentrations alkalis, Rb, Nb, Ta, Hf. Their peraluminous (molar Al2O3/[CaO + Na2O K2O] = 1.06–1.15) low-P (P2O5 < 0.008 wt%) character identify them as highly I-type granites. primary magma most likely generated partial melting juvenile crust ANS. We document numerous lines evidence that formed extensive fractional crystallization followed interaction magmatically-derived, F-rich hydrothermal solutions. REE patterns show marked negative Eu anomalies (Eu/Eu? 0.01–0.15) well prominent M-type tetrad effects (TE1,3 1.332–3.536), typically seen differentiated granites attributed exchange fluid. Anomalous ratios isovalent “twin” elements such Nb/Ta, Zr/Hf, Y/Ho likewise indicate accessory restricted Mn-rich part columbite-tantalite series; this manganoan trend characteristic Likewise, presence wodginite, a Sn-bearing mineral, unique fingerprint evolved Late-stage overprint mineralization preserved rims fluorcalciomicrolite partly replacing columbite-(Mn) tantalite-(Mn). Accumulation residual volatile-rich melt exsolved fluids upper chamber produced stockscheider pegmatite, greisen, quartz veins cut peripheries surrounding country rocks.