PETROGRAPHICAL AND GEOCHEMICAL CHARACTERISTICS OF SADAT FORMATION AND ITS DEPOSITIONAL ENVIRONMENT, SADAT AREA, WEST GULF OF SUEZ, EGYPT. ESMAT A. ABOU EL-ANWAR and AMR M. EL-GORARY Geological and Geophysical Scis. Dept., National Research Centre, Cairo. The depositional basin of the Sadat Formation is tectonically controlled by the intense rift movements which led to the formation of topographically low land (Sadat area) surrounded by the Eocene highs (Gebel Ataqa, Gebel EI-Galala El-Bahariya, etc). It is of Late Burdigalian age. Petrographically, the Sadat Formation consists mainly of two facies types: a) dolomitic calcareous sandstone facies (foreshore deposits) which is the basal horizon and represents the beginning of the Miocene transgression. b) reefal limestone facies (back reef deposits) which represents the maximum Miocene sea level. Diagenetically, the reefal carbonates of the Sadat Formation were subjected to three paragentic stages. Geochemically, the sediments of the Sadat Formation are of low Mg content relative to the basal horizon that shows a rather limited dolomitization process. The reefal carbonates of the Sadat Formation are impoverished in Na, K, Sr contents due to their suffering from the diagenetic processes in a less saline environment than seawater.