Coralline Red Algae and Microfacies studies as environmental indicators: A case study from the Gharamul formation, Gulf of Suez Region, Egypt

The systematic studies and taxonomic investigations carried out on the Early Miocene Gharamul Formation exposed in Gebel Abu Shaar El Qabili plateau, western side of the Gulf of Suez region, led to the recognition of twelve coralline algal species belonging mainly to five genera of three subfamilies (Mastrophoroideae, Lithophylloideae, and Melobesioideae) of Rhodophyta (Corallinaceae). The geniculate coralline algae are relatively scarce and represented by a single genus Corallina sp. The Mastophoroids (Neogonilithon and Spongites) and Lithophylloids (Lithophyllum) are more dominant coralline algal species and dominate the shallower coralline algal assemblages. On the other hand, Melobesioids (Mesophyllum and Lithothamnion) and sporolithales (Sporolithon) are the most abundant components and diverse in the deeper-water assemblages. The Gharamul Formation (Burdigalian) consists of a thick carbonateclastics succession. The lower part consists of a cyclic sequence of laminated, fossiliferous and argillaceous limestone intercalated with mudstone, and sandstones. It is documented that the clastic microfacies have good reservoir quality in the region due to the impacts of dissolution and fracturing diagenetic processes. The carbonate microfacies are impervious due to the effects of cementation, and micritization. The dominance of coralline algae and larger benthic foraminifera indicate deposition in the photic zone. Frequent oscillation of lower-energy (foraminiferal wackestones) with higher-energy (grain-supported grainstones, packstones and rudstone) suggest the likely incidence of cyclones/storms during the depositional time.