Integration of subsurface and outcrop data to evaluate the mineralogy, geochemistry, and hydrocarbon potentiality of Duwi black shale Formation at Kharga and Dakhla depressions, Western Desert, Egypt

Abstract

The black shale successions in Egypt remain insufficiently investigated, particularly with respect to their geochemical and mineralogical properties. Accordingly, this study presents a comprehensive evaluation of the Cretaceous Duwi Formation in the Kharga and Dakhla depressions of Egypt’s Western Desert through an integrated geological, mineralogical, and geochemical approach. This work is based on several geochemical analyses, such as XRD, XRF, total (sulfur, organic carbon, and carbon), Rock Eval Pyrolysis (RE-P), and Pyrolysis Gas Chromatography that were undertaken on the collected black shale samples. Mineralogical results confirm that smectite and kaolinite are the primary clay components in Mut-Manflout. A strong correlation between major oxides and common trace elements reveals a detrital provenance; by contrast, the elevated chemical index of alteration reflects an intensive degree of weathering within outcrop samples. Geochemical outcomes reveal that the core and outcrop samples remain thermally immature, with TOC fluctuating between 0.19 and 1.59 wt.%, a limit of poor potential within outcrop samples, whereas it ranges from 0.27 to 3.57 wt.%, a limit of excellent potential within core samples. The studied core samples are classified as Type I–II to Type II–III kerogen, representing the reliable limit of the oil-gas-prone area, while the outcrop samples are classified as Type III–IV kerogen, indicating a gas-prone limit. A notable association between TOC level and S 1 +S 2 value indicates good generation potential for primary core shale samples; however, reflects a poor category for the outcrop shale samples at the selected sections. Collectively, the findings highlight the Duwi Formation black shales as an underexplored unconventional resource with variable hydrocarbon potential across the Kharga and Dakhla depressions.