Paleoclimate and Depositional Controls on Organic Carbon Storage and Sustainable Unconventional Resource Potential of Late Cretaceous–Paleocene Black Shales, Dakhla Basin, Egypt

Abstract

The Dakhla Formation in the Western Desert of Egypt comprises a thick Cretaceous–Paleocene, ranging from light gray to dark gray, that represents an underexplored geological resource relevant to sustainable energy and environmental conditions. The present study integrates mineralogical and geochemical data based on samples collected from outcrop at Mut-Manflout and subsurface core samples from Abu Tartur (62–150 m depth) to evaluate depositional environments, paleoclimate, chemical weathering, and organic carbon accumulation. Major and trace element geochemistry, clay mineralogy, total organic carbon (TOC), Rock-Eval pyrolysis, and calorific values are used to assess hydrocarbon potential while minimizing exploration uncertainty. Mineralogical analyses indicate that smectite and kaolinite dominate the Mut-Manflout shales; in contrast, significant relationships among primary oxides and trace elements indicate a source from detrital materials, and elevated Chemical Alteration Index (CIA) values are indicative of intense chemical weathering under humid paleoclimatic conditions. The geochemical results show that Abu Tartur shale core samples contain higher TOC values (0.73–2.08 wt%) and oil-prone kerogen (types I–II to II–III), while Mut-Manflout outcrop samples exhibit lower TOC contents (0.23–1.15 wt%) and gas-prone kerogen (types III–IV). Both successions are thermally immature, with a strong relationship between TOC and S1 values indicating the presence of indigenous hydrocarbons. By comparing surface and subsurface shales, the present study highlights the importance of site-specific characterization in reducing environmental and economic risks associated with unconventional resource exploration. The results support sustainable resource planning by improving understanding of organic carbon storage, paleoclimate controls, and the responsible evaluation of black shale systems in arid regions such as the Western Desert of Egypt.