الفهرس 
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Abstract
This work aims to shed light on the lithostratigraphy, depositional environment and sedimentological history of the Eocene carbonates exposed in Eastern Desert of Egypt, beside the nature of contact between Thebes and Esna formations. The validity of the carbonate sequence in the study area as raw material in cement industry also has been discussed.
To achieve these objects, an area of about 150 km along the Red Sea coast, in Eastern Desert, between Latitude 25º 30”, 28º 00” North, and Longitude 33º 00”, 35º 00” East, was studied. Four stratigraphic sections were measured, sampled, and described in detail. These sections are distributed from south to north as follows; Gebel Hamadat, Wadi Syatin, Gebel Wasif and Wadi Malha sections. Total 226 representative field samples were collected. About 150 microscopic thin sections were made and examined under the microscope. Detailed petrographic analysis and water energy index were carried out. And staining technique was followed to differentiate the dolomites in the samples.
Stratigraphically: the lower Paleogene sequence in Eastern Desert of Egypt is represented by the upper part of Esna Formation overlain by Thebes Formation.
The studied part of Esna Formation is of lower Eocene age while the late Paleocene part is not represented. It is represented by dark grey to green calcareous shale flooded by small foraminifera at the base of studied sections. It’s thickness range between 5 and 10 m.
In the study area, Thebes Formation records maximum thickness at Hamadat section (105 m thickness), while Syatin, Wasif and Wadi Malha sections recorded thinner successions (70, 72, 65 m thickness) in order. This variation in thickness may be related to differences in sedimentation rates or post-depositional erosion related to tectonic.
Thebes Formation composed mainly of laminated to thinly bedded fine-grained limestone, dolomitized limestones and chalk. Scattered nodules, concretions or bands of chert (flint) is represented through the succession but became more common in the upper portion.
Thebes Formation unconformably overlies Esna Formation at the studied sections with sharp or gradational contact.
Sedimentologically: based on field observation and petrographic analysis; four main facies belts are identified. These facies belts in brief are:
Tidal flat facies belt is detected overall the study area. It is considered as the main building facies of Thebes Formation. It’s thickness range between about 60 m at Wasif and Hamadat sections, and about 35 m at Syatin and Wadi Malha sections.
The prevailing rock types are white thin laminated to papery lime mudstone with scattered chert nodules (2-20 cm diameter) and bands. This lime mudstone facies ranges from pure to dolomitized lime mud and may be silicified at certain horizons especially at the upper parts. Both vertical and horizontal bioturbation is recorded within the sediments of this facies. At the upper part of this facies, the papery limestone grades into concretionary limestone with more flint nodules.
In thin section, two types of dolomite rhombos can be identified. The first type is fine-grained rhombs ranging from 10 to 50 µm. The second type is less abundant. The allochemes are mainly fragmented parts of echinoderms, gastropoda and foraminiferal chambers. Sometimes,