Generation of hydrocarbons in the burial history of Silurian formations in the Libyan part of the Ghadames Basin

Burial history, temperature variations, and organic matter maturation in the sedimentary rocks in the Ghadames Basin were numerically reconstructed using the GALO system for basin modeling taking into account repeated tectonic (stretching) and thermal activation events in the basin lithosphere. The modeling improved the reconstruction of the thermal history of the basin and hydrocarbon generation potential compared with previous model estimates based on the assumption of a constant temperature gradient during the whole period of basin development. In particular, the results of modeling suggest that the amplitude of Cenozoic erosion was smaller than that proposed in previous studies. The central part of the Ghadames Basin, which was considered in this study, is the western part of the Libyan sector of the basin, which underwent intense subsidence reaching 4000 m already in the Carboniferous. Given the relatively active thermal history of the basin, the modeling suggests high degrees of organic maturity in the source rocks of the Lower Silurian in the modern section of the basin and confirms the high generation potential of liquid and gaseous hydrocarbons in these formations. Significant hydrocarbon generation has occurred there since the Late Carboniferous. On the other hand, the generation potential of the Late Devonian (Frasnian) sequences is limited and strongly dependent on burial depth. The main stage of hydrocarbon generation in these rocks coincided with the Cenozoic thermal activation of the basin lithosphere. In all the areas considered, the oil window overlaps a significant portion of the modern sedimentary section of the Ghadames Basin.