Facies analysis and interpretation

lithofacies types (LFT) were distinguished in the Miocene studied sections on the Cairo- Suez District (Tab. 2, Figs. 2, 3). The description and classification of these lithofacies types depend on the following: textures, mineralogy, rock color, grain size, sorting, components (skeletal or non skeletal), thickness of different rock unit, bedding style, sedimentary features, interpretation of depositional setting and the appearance according to lithofacies code (Fig. 4). In general, the studied sections are divided into two lithostratigraphic units namely, the Gharra Formation and the Genefe Formation in ascending order, according to Ghorab and Marzouk (1965).

The Gharra Formation rests unconformably on sediments of Oligocene age (sands and gravels) with silicified woods in both Gabal Gharra and Gabal Homeira sections, while in Gabal Geneifa one the base of the formation is unexposed. In all the three sections, the Gharra Formation is conformably overlained by the Genefe Formation, and consists mainly of clastics (shale, claystone, marl and sandstone) with sandy limestone interbeds. The limestones are low or moderate fossiliferous to highly fossiliferous, containing rich assemblages of macrofossils.

The Genefe Formation rests conformably on the sediments of Gharra Formation and its top is not covered in the three sections and it consists mainly of algal, reefal and chalky limestones with oyster banks, mudstone and calcareous shale intercalations. 98 The limestones and calcareous shales are low or moderate fossiliferous to highly fossiliferous with macrofossils assemblagaes.

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