Eocene Stratigraphy, Facies, Sequenses and Depositional History in Shabraweet Area, North of Suez, Eastern Desert, Egypt

The Eocene rocks in Shabraweet area comprise the Lower, Middle and Upper Eocene stages. Each stage consists of only one rock unit; the Minia Formation, the Mokattam Formation and the Maadi Formation, respectively. The Minia Formation shows angular unconformity relationship with the underlying Cretaceous rocks and disconformity relationship with the overlying Mokattam Formation. The Maadi Formation is also unconformably overlying the Mokattam Formation and is separated from the underlying Oligocene sediments by a conglomeratic bed. Eighteen microfacies associations are recorded in the rocks units. Five constitute a clastic facies (polymictic conglomerates, calcareous quartzarenites, lithic quartzarenites, ferruginous quartzarenites and claystone), ten constitute a limestone facies(lime mudstone, sandy lime mudstone, alveolinid wackestone, ostracoda foraminifera wackestone, sandy Somalina wackestone, foraminiferal wackestone, sandy miliolidae packstone, dolomitic oyster packstone, miliolidae grainstone and algal miliolidae grainstone) and three constitute a dolostone facies(sandy dolostone, dolostone and sandy dedolostone). Two types of cycles are recorded in the study area; the first one is shallowing upward with several varieties (in pure clastic facies, in mixed clasticcarbonate and in pure carbonate facies). The other cycles are deepening upward in pure clastic facies, recorded only at the base of the Maadi Formation. Three depositional sequences are recognized in the study area. They are sequence1, sequence 2 and sequence3 represented the Lower Eocene, the Middle Eocene and the Upper Eocene, respectively. These sequences are separated by sequence boundaries represented by unconformity surfaces The Minia Formation was deposited in a shallow marine environment. The Mokattam Formation was deposited in shallow tropical and subtropical zones, with normal salinity water and fair high rate of sedimentation. The Upper Eocene was deposited in shallow agitated water with high influx of clastics. 1INTRODUCTION AND PREVIOUS WORK The Shabraweet region covers an area of about 300Km2. It is limited from the east by the IsmaliaSuez road and from the west by the tributaries of Wadi Abo Talh and by Gebel Um-Kathieb. It is bounded from the north and south by the plain of the Great Bitter Lake. It lies between Latitudes 30o15/ and 30o 21/N. and Longitudes 32o 13/ and 32o 20/E (Fig.1). The exposed rocks in the study area range from Lower Cretaceous to Recent. The regional stratigraphy of the Eocene of Sabraweet area has been studied by different authors (e.g. Barron, 1907; Blanckenhorn, 1921; Barthoux, 1922; Foly, 1941; Fawzi, 1959a; Faris and Abbass, 1961; Said, 1962; Barakat and Abu Khadra, 1971; Barakat and Aboul Ela, 1972; Al-Ahwani, 1982; Helal, 1990 and Mostafa & Hassan, 2004). The present study focuses on the Eocene rock stratigraphy, facies development, sequences and depositional history. Two stratigraphic sections of the Eocene sequence were measured, sampled and described reflecting coeval environments along east-north direction. More than one hundred thin sections were prepared and examined for their composition texture and microfossil assemblages. The petrographic description of the sandstones follows Pettijohn et al. (1973). The terminology of limestones and dolostones is based on the classification of Dunham (1962). Calcite was distinguished from dolomites by staining technique of Friedman, (1965). 2STRATIGRAPHY The Eocene rocks show the widest distribution in the north Eastern Desert of Egypt. These rocks are cropping out at the Southern and Northern Galala plateaux, Gebel Ataqa and Gebel Shabraweet which represents the extreme northern Eocene outcrops in the Eastern Desert. The Eocene succession in the study area is subdivided into two Lower Eocene, Middle Eocene and Upper Eocene rocks. 2.1. Lower Eocene rocks The Lower Eocene rocks in the Shabraweet area is represented by the Minia Formation.