Abstract
The Silurian "hot shale" is the principal Paleozoic source rock in the Ghadames Basin and has played a fundamental role in the generation of hydrocarbons across North Africa. This study investigates the occurrence and regional distribution of organofacies, thermal maturation, and petroleum generation history of the Silurian hot shale through an integrated interpretation of organic geochemical, petrological, and basin modeling datasets. Source rock quality was evaluated using total organic carbon (TOC), Rock-Eval pyrolysis, hydrogen index (HI), kerogen typing, and biomarker analyses, while thermal maturity was constrained using vitrinite reflectance equivalent (Ro), Tmax, and calibrated burial and thermal history models. The results indicate significant lateral variations in organic facies controlled by depositional environment, paleogeography, and post-depositional burial evolution. Organic-rich intervals are dominated by marine Type II kerogen, with localized Type II/III mixtures reflecting changes in sediment influx and oxygenation conditions. Thermal maturity increases progressively from basin margins toward the depocenters (up to 2.4 VRo), where the source rock has reached the peak to late oil generation window and locally entered the wet gas stage. One-dimensional basin models suggest that petroleum generation commenced during the Late Paleozoic following deep burial associated with Hercynian tectonism and accelerated through subsequent Mesozoic subsidence. Hydrocarbon expulsion occurred predominantly during the Triassic to Jurassic, coinciding with maximum burial and favorable migration conditions. These findings provide new insights into the regional petroleum system evolution of the Ghadames Basin by linking organofacies variability with maturation history and hydrocarbon generation timing. The integrated workflow enhances the understanding of source rock behavior and contributes to reducing exploration risk and improving conventional and unconventional hydrocarbon resource assessments across the basin.