Tectonic and Chronological Implications of Zircon U-Pb Dating on the Arabian–Nubian Shield, the Gabal Mukattab, Sinai, Egypt

The granitic and metamorphic rocks at the Gabal Mukattab area represent the north termination of the Arabian–Nubian Shield in Sinai, which, in turn, represents the northern part of the East African Orogeny. The geochronological dynamics of the magmatism that constructed the Arabian–Nubian Shield are critical in understanding these orogenies. Our study involved dating three metamorphic rocks (846 ± 4 Ma to 818 ± 5 Ma), five calc-alkaline granitic rocks (728 ± 6 Ma to 609 ± 5 Ma), and eleven alkaline granitic rocks (678 ± 7 Ma to 555 ± 3 Ma). In the studied region, the island-arc phase of magmatism activated between 846 ± 4 Ma and 818 ± 5 Ma. The consequent syn-collisional magmatism initiated from 728 ± 6 Ma to 668 ± 5 Ma, demonstrating the temporal domination of the subduction-related compressional regime. The post-collisional magmatism started at 610 ± 5 Ma, marking the shifting of the tectonic setting from a compressional to an extensional regime. The phase of magmatism dominated until 555 ± 3 Ma in the studied region, suggesting extending the ANS magmatic activity until the Phanerozoic edge. These findings challenge the classical distinction between older magmatism, characterized by calc-alkaline granitoids, and younger magmatism, characterized by alkaline granitoids. The pre-Neoproterozoic (pre-ANS) 16 zircon xenocrystals with ages ranging between 2084 ± 9 Ma and 1094 ± 8 Ma were yielded, which might support a reworked ancient magmatic source. Seven Phanerozoic zircons showed ages between 495 ± 3 Ma and 374 ± 4 Ma, hinting at potential Ordovician–Devonian magmatic events in the region.