PETROGENESIS AND MINERALIZATION OF THE ABU DABBAB ALBITE GRANITE: INSIGHTS INTO RARE METAL A TYPE GRANITES IN THE ARABIAN–NUBIAN SHIELD

The Arabian–Nubian Shield (ANS), spanning northeast Africa and the Arabian Peninsula, evolved during the Neoproterozoic collision of East and West Gondwana and the closure of the Mozambique Ocean. Following a significant post-collisional phase beginning around 620 Ma, the ANS stabilized by 540 Ma and witnessed intrusive events featuring rare-metal–enriched granitoids. Among these, the Abu Dabbab albite granites (ADG) in Egypt’s Central Eastern Desert stand out due to their high concentrations of Nb, Ta, Sn, Zr, and REEs, and their petrogenesis remains debated. Our integrated field, petrographic, mineralogical and geochemical investigations reveals that the ADG are peraluminous, high‑SiO₂, highly fractionated calc-alkaline plutons emplaced ANS’s transitional tectonic regime. ADG characterized by high Rb/Sr, elevated Nb–Ta–Sn–Hf contents and strong negative Eu anomalies aligning with muscovite-bearing, evolved A-type granite suites with substantiate a crustal source influenced by juvenile mantle-derived underplating. We propose a petrogenetic model where lithospheric thinning and magmatic underplating triggered hydration and melting of micas-rich crustal rocks. The resultant F-rich, peraluminous melts underwent prolonged fractional crystallization under magmatic–hydrothermal conditions, producing Ta–Nb–Sn mineralization and greisen–vein systems.