Sharp-based shoreface sandstones in the Early Carboniferous sediments of the Awaynat Wanin area (western Libya)

The Awaynat Wanin exposure is the closest outcrop analogue for Palaeozoic strata deposited in the subsurface of the Ghadames basin. This study focuses on Lower Carboniferous strata, examined on the edge of the extensive Al Hammadah al Hamra plateau. The desert and rocky conditions of the area provide excellent exposures that are poorly documented. Our new dataset comprises 1500 m of sedimentary logs acquired along an 80 km transect. The results are present as a revised composite section for this exposure, which using integrated GPS and satellite data, re-assesses the maximum thickness of the Marar at 800 m. The excellent exposures also allow evaluation of lateral variability. Detailed facies analysis supports a dominantly marine environment of deposition, characterised by 45 sedimentary cycles that typically record transition from offshore mudstone to sandy shoreface facies and sometimes palaeosols. In the regional context of an inactive tectonic setting at deposition time in the Early Carboniferous, these numerous upward shallowing cycles are interpreted to record relative fluctuations of eustatic sea level. The Awaynat Wanin exposures therefore offers a valuable record to improve understanding of the Early Carboniferous variations of the sea level.