Sedimentary
Environments and Depositional Characters of the Middle-Upper Eocene Succession
in the Fayum Depression, Egypt
Abdel-Fattah, Zaki A.1, Murray, K. Gingras1,
Michael, W. Caldwell1, S. George Pemberton1 (1) Alberta University, Edmonton, AB
Eocene strata in Egypt are extremely fossiliferous and have good reservoir potential. Two
middle-upper Eocene successions exposed in outcrop in the Wadi
El-Hitan (Whale Valley) and Qasr
El-Sagha areas of the Fayum
depression were examined, Egypt. Based on sedimentological
and ichnological data, six facies
associations (FA) are identified. The middle Eocene Gehannam
Formation is represented by a stacked facies
succession of thoroughly-burrowed sandstones, bedded mudstones, and muddy
sandstones with mangrove roots of FA (1a, 2a, 2b), respectively. Highly
burrowed sandstones and sandstones with coquina of FA (1b, 3) comprise the
entire middle-upper Eocene Birket Qarun
Formation. The interbedded sandstones and coquina of
FA 4a and the carbonaceous sandy shale of FA 4b represent the lower Temple Member. Finally, the
cross-bedded sandstones of FA 5 and the sandstones/mudstones of FA6a-f form the
upper Dir Abu Lifa Member of the upper Eocene Qasr El-Sagha Formation. Both
tectonics and relative sea-level fluctuations play an important role in the
distribution of these facies associations and their
corresponding depositional environments. The defined facies
associations record a gradual shallowing. The overall
receding of the Tethys from south to north resulted
in an upward transition of the depositional environment from a large open
marine bay or gulf covering the southern and central Fayum
(during the middle Eocene), to marginal-marine environments that prevailed in
the central and northern Fayum areas (during the late
Eocene). Facies Association 1 records a distal open
marine bay or gulf that is succeeded by a bay-margin environment (FA2) and is
topped by a costal/ravinement setting (FA3). Upwards,
marginal-marine lagoonal/bay parasequences
(FA4) are followed by regressive, deltaic distributary
channels (FA5). The capping unit, Facies Association
6, records an estuarine-channel depositional environment.