Remote sensing, petrogenesis and tectono-magmatic evolution of the Wadi Queh-Wadi Abu Shigeili area: a window into the transitional history of the central Egyptian-Nubian Shield from pre-plate collision to post-collision magmatism

The Wadi Queh–Wadi Abu Shigeili area in the Central Eastern Desert of Egypt provides a comprehensive geological record of the Arabian-Nubian Shield, particularly during the Neoproterozoic Pan-African Orogeny. An integrated approach combining remote sensing, field mapping, petrography, and geochemical analyses was conducted to elucidate the transition from pre-collision island arc magmatism (~ 820–700 Ma) to post-tectonic extensional setting (~ 616–542 Ma). Remote sensing using Landsat-8 OLI data, processed through principal component analysis and band rationing, effectively distinguishes diverse lithological units, including the immature island arc metavolcanics, continental margin Dokhan volcanics, collision-related gabbros, and post-collision granites. The metavolcanics (~ 746 Ma) exhibit tholeiitic to calc-alkaline affinities, characterized by depletion in high-field strength elements (HFSE; Nb, Ta) and enrichment in large-ion lithophile elements (LILE; Rb, Ba), indicating a subduction-modified mantle source. The Dokhan volcanics (~ 659–598 Ma) show calc-alkaline characteristics, evident in their elevated SiO₂ content alongside an enrichment in LILE (Rb, Sr) and depletion in HFSE (Nb, Ta), reflecting arc-continent collision. The transition from tholeiitic to calc-alkaline compositions signifies increasing crustal assimilation and fractional crystallization of mantle-derived magmas, which is characteristic of a maturing arc system. Collision-related gabbros (~ 634–599 Ma) are compositionally intermediate, displaying enrichment in LILE (Rb, Sr) and depletion in HFSE (Nb, Ta), consistent with a metasomatized mantle source influenced by subduction processes. Post-collision granites display A-type geochemical signatures, marked by high-K and elevated Nb, Zr, and Y, suggesting derivation from crustal melting under extensional conditions during orogenic collapse. The molasse-type Hammamat sedimentary rocks in the Queh and Abu Shigeili basins document syn and post-collision depositional environments, capturing the transition from compressional to extensional tectonics. These rocks exhibit geochemical features indicative of mixed felsic to mafic igneous sources, aligning with the region’s complex magmatic evolution. This study delves into the dynamic interplay between compressional and extensional forces and their role in the evolution of the Central Eastern Desert.