Formation-Scale Lithostratigraphic Subdivision of the Nubian Sandstone Succession Along the Quseir–Qift Road, Eastern Desert, Egypt

The Nubian Sandstone succession exposed along the Quseir–Qift Road, Eastern Desert, Egypt, has commonly been treated as a broad sandstone-dominated interval, limiting local stratigraphic resolution. This study establishes a formation-scale lithostratigraphic subdivision of that succession. Field control comprises 18 Global Positioning System (GPS)-referenced localities—15 within the Quseir–Qift corridor and three comparison localities at Wadi Hammamat. Principal measured-section controls, contact localities, and lateral checks were organized into eight composite logs within a 1:25,000 mapping framework. From base to top, the succession comprises the Araba, Abu Thora, Abu Durba, Malha, Bahariya, and Taref formations, with recorded thicknesses of 77.5–84.5 m, 68–72 m, approximately 24 m, approximately 78 m, 37–60 m, and 7–37 m, respectively. Formation boundaries were distinguished from ordinary facies changes by persistent package-scale shifts in lithological association and vertical organization, reproducible stratigraphic position, and traceable contact or marker relationships where exposure allowed. Regional correlation was evaluated only after local differentiation. The observed facies associations are consistent mainly with fluvial systems, with local tidal or shallow-water influence in Araba and Abu Thora and a restricted evaporitic setting in Abu Durba. Because no independent local biostratigraphic or geochronologic ages were obtained, formation ages remain regional, correlation-based assignments and may be diachronous. The framework improves local stratigraphic resolution without proposing new formal units or a definitive regional solution for the Nubian Sandstone.