Despite widespread organic-rich accumulations in southern Tethyan basins during the Late Cretaceous greenhouse, the relative role of climate-derived weathering, redox regime, paleoproductivity, and regional tectonics in controlling organic matter enrichment and preservation remains poorly constrained. This work investigates how these interacting geological processes governed organic matter richness and redox evolution in Campanian-Maastrichtian strata of the Abu Tartur Plateau, Dakhla Basin (southern Western Desert, Egypt). The study combined bulk-rock elemental and organic geochemical and sedimentological data from phosphates, black and gray shales, limestones, and glauconites of the Phosphate, Liffiya Shale, and Maghrabi Shale members of the Duwi Formation and the overlying Dakhla Formation. Chemical index of alteration (CIA), C-value and other elemental proxies revealed deposition under predominant humid climates and intense continental weathering, interrupted by short-lived arid-semi-arid to semi-humid intervals, corresponding to the development of phosphorite and carbonate beds. These climatic and weathering trends coincide with coeval intervals from the Red Sea and Nile Valley, reflecting the regional geological processes at the near-equatorial southern Tethyan margin during the Campanian-Maastrichtian. Source rock characterization indicates poor to very good with a few intervals of excellent organic matter richness and kerogen Type III with minor Type II. The deposition of the Duwi and Dakhla formations was concurrent with episodic subsidence versus uplift of the Gilf El-Kebir spur and Nubian Swell, consistent with sea-level rise and increased accommodation space and induced upwelling in open shelf settings of the southern Tethys. These conditions governed O2 replenishment faster than consumption leading to oxic-suboxic environments dominated by organic-rich deposits via organic matter production under enhanced upwelling than persistent anoxia. Conversely, black shales of the Maghrabi Shale Member were deposited under anoxic settings accompanied by elevated biological productivity. Preferential Mo enrichments in black shales compared to limited enrichments of other redox-sensitive metals suggest the operation of a particulate shuttle during short-term redox fluctuations. The mechanism behind enhanced anoxia included episodes of relative sea-level fall and decreased accommodation space along with regional tectonic uplift of adjacent uplands, resulting in a semi-enclosed basin with restricted circulation that promoted nutrient supply and oxygen depletion, favorable for organic matter preservation. The Dakhla Formation was deposited in similar marine environmental conditions to the Liffiya Shale Member; however, intensified weathering and associated terrigenous supply versus limited biological productivity and well-ventilated water column resulted in a strong dilution of labile organic matter and deposition of organic carbon-lean shales.