Combined petrographic and geochemical methods are utilized to investigate the provenance, tectonic setting, palaeo-weathering and climatic conditions of the Cambrian Araba clastic sediments of NE Egypt. The ~ 60 m thick Araba Formation consists predominantly of sandstone and mudstone interbedded with conglomerate. Petrographically the Araba sandstones are mostly sub-mature and classified as subarkoses with an average framework composition of Q₈₀F₁₄L₆. The framework components are dominated by monocrystalline quartz with subordinate K-feldspar, together with volcanic and granitic rock fragments. XRD analysis demonstrated that clay minerals comprise mixed-layer illite/smectite (I/S), illite and smectite, with minor kaolinite. Diagenetic features of the sandstone include mechanical infiltration of clay, mechanical and chemical compaction, cementation, dissolution and replacement of feldspars by carbonate cements and clays. The modal composition and geochemical parameters (e.g. Cr/V, Y/Ni, Th/Co and Cr/Th ratios) of the sandstones and mudstones indicate that they were derived from felsic source rocks, probably from the crystalline basement of the northern fringe of the Arabian–Nubian Shield. The study reveals a collisional tectonic setting for the sediments of the Araba Formation. Palaeo-weathering indices such as the chemical index of alteration (CIA), chemical index of weathering (CIW) and plagioclase index of alteration (PIA) of the clastic sediments suggest that the source area was moderately chemically weathered. On the northern margin of Gondwana, early Palaeozoic weathering occurred under fluctuating climatic conditions.

A geochemical analysis has been conducted on twenty-six sediment samples spanning the P–E boundary interval collected from the Esna Shale in three well-dated stratigraphic sections in west-central Sinai, Egypt to interpret paleoenvironmental changes associated with the P–E boundary events. The Esna Shale consists of hemipelagic marine shales and marls and it is subdivided stratigraphically into the uppermost Paleocene Hanadi Member unconformably overlain by the lowermost Eocene Dababiya Quarry Bed (DQB) and El-Mahmiya members. A variety of geochemical proxies including the Al-normalized elemental concentrations and redox-related elemental ratios and parameter (V/Cr, V/V + Ni and Mn*) and productivity indicators (P _org and Ba _bio ) were employed for paleoceanographic interpretations. Across the P–E transition, the concentrations of SiO ₂ , TiO ₂ , Al ₂ O ₃ Fe ₂ O ₃ , MgO, V, Cr, Ni, Cu, Rb, and Zr notably increased, whereas the concentrations of CaO, MnO, Sr, and Zn abruptly decreased. The variation in the elemental concentrations is attributed to the carbonate dissolution because of increased ocean acidification as well as a brief increase in the detrital influx associated with the brief humid interval at the base of the Eocene. The Al-normalized detrital-related elements (Ti, Zr, and Rb) values show a relatively homogeneous profile suggesting a uniform detrital input from an unchanged source rock. The simultaneous significant increase in the V/Cr and V/V + Ni ratios and enrichment of Ni, Cu, and Zn in the sediments of the DQB suggest that the depositional basin experienced dysoxic to slightly anoxic bottom conditions. The coeval increase in the P _org and Ba _bio in the sediments of the DQB suggests an increase in nutrients availability and consequently primary productivity possibly due to enhanced upwelling during early Eocene.