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Volume :15 Issue : 2 1988
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Depositional and diagenetic models of the Miocene evaporites on the Gulf of Suez coast, west-central Sinai, Egypt
Auther : EL SAYED A. A. YOUSSEF, G. PHILIP AND A. M. KAMEL
Department of Geology. Faculty of Science, Cairo University, Giza. Egypt
ABSTRACT
The Miocene evaporites on the Gulf of Suez coast between Wadi Sudr and Wadi Gharandal. west-central Sinai. are interpreted as coastal embayment deposits. Field, petrographical and mineralogical studies revealed that the evaporite sequence consists mainly of gypsum and anhydrite intercalated with fissile shale and massive bituminous limestone. The evaporates occur in three main forms: ( I ) nodular, mosaic and massive crystalline secondary gypsum characterized by porphyrotopic, alabastrine and granotopic textures; (2) swallow-tail and spicchiolino (mirror-like) gypsum; and (3) white dense powdery anhydrite composed of felted masses of anhydrite laths with minor amounts of porphyrotopic and satin-spar gypsum. The evaporite sequence overlies coral-algal limestone, representing coastal facies. near Wadi wardan, whereas a thin conglomerate layer and algal glauconitic intrapelsparite facies, representing a semirestricted lagoonal facies, is recognized at the base of the evaporite sequence at Wadi Gharandal. Bacterial action. dehydration of primary gypsum and subsequent transformation of the anhydrite into secondary gypsum are the main diagenetic processes affecting the evaporites.