Depositional Evolution Of The Eocene Sediments, Fayum Area, Egypt

The Middle-Upper Eocene sediments of the Fayum District are represented by Gehannam, Birket Qarun and Qasr El-Sagha formations. Both field studies and laboratory analyses on the concerned sediments have enabled to distinguish six lithofacies. These lithofacies proved that the present sediments were deposited in transitional paralic environment of active northward - prograding deltaic subenvironments contemporaneous with rabid but gradual sea - level drop. It is started with the delta front silt-shale (Gehannam Formation) of 20 m thick, followed by distributary mouth bars of cross-bedded sandstone (Birket Qarun Formation, of 50 m thick). Both the lower and upper delta plains attain thicknesses of 99 m and 38 m prospectively and are represented by the lower part of Qasr El-Sagha Formation. The deltaic sequence is topped with 45 m thick of aeolian sands representing the upper part of Qasr El-Sagha Formation. This unit represents an extensive desertification phase closes the depositional history of the succession examined.