CALCAREOUS NANNOPLANKTON AND DIATOMS FROM THE EOCENE PLIOCENE SEDIMENTS, FAYOUM DEPRESSION, EGYPT

Different assemblages of calcareous nannofossil and diatom taxa are detected in samples collected from sections at Shaqluf, Siela and Qaret El Faras in the Fayoum area. Five calcareous nannoplankton biozones are recorded: the Middle Eocene Discoaster tanii nodifer Zone, the Discoaster saipanensis Zone; the early, Late Eocene Chiasmolithus oamaruensis Zone; the Late Eocene Isthmolithus recurous Zone and the Early Pliocene Reticulofenestra pseudoumbilicus Zone. Diatoms are recorded for the first time in the sections studied. The gradual changes in diatom composition from marine to brackish, ending with a well-developed, freshwater flora at the top of the Pliocene Shaqluf section, indicate changes in the palaeoecological conditions in the area during that time. In the Pliocene Siela and Qaret El Faras sections, all the identified diatom taxa belong to the freshwater assemblage together with some brackish water forms. The predominance of freshwater diatoms suggests that these taxa were introduced to the area with the sediments of the Palaeonile river during the Late Pliocene.