Stratigraphy, Sedimentology and Depositional Environments of the Late Ordovician Succession in Al Kufrah Basin, SE Libya

Outcrops on the northern and south-eastern flanks of Al Kufrah Basin, Libya (Jabal Azbah and Jabal az Zalmah) help to improve understanding of the End-Ordovician (Hirnantian) glacial event in Gondwana. Several glacial erosion surfaces are identified, attributed to waxing and waning of ice sheets extending into the marine environment, and the sedimentary succession reveals an extensive glacial outwash fan apron deposited on a broad, shallow continental shelf. During deglaciation, fluvial and tidal cross-bedded sandstones were deposited in the southeast of Al Kufrah Basin and the entire region was overlain by Tanezzuft shales, siltstones and fine sandstones. Evidence from Al Kufrah Basin strongly suggests an extremely broad continental shelf setting during the Lower Palaeozoic, with implications for the morphology and dynamics of the ice sheet margin, and the availability of accommodation space during deglaciation. These implications must be considered when developing and refining depositional models for Lower Palaeozoic petroleum plays in the basin and elsewhere in Libya.