Response of foraminiferal assemblages on the middle Eocene climatic optimum and following climatic transition in the shallow tropical sea (the south Fayoum area, Egypt)

Foraminiferal assemblages from 4 sections (totalling 158 samples) were quantitatively analysed to reconstruct paleoenvironmental changes in inner to outer shelf, tropical epicontinental sea of the southern Peritethys area around the middle Eocene climatic optimum. In comparison with bathyal oceanic sites, shelf assemblages from Fayoum area are strongly influenced by climatically forced sea-level oscillations and aridification in cooling post-MECO interval. Pre-MECO interval can be characterized by gradual deepening and hypoxic, eutrophic bottom water. The maximal deepening during the temperature peak was associated with destruction of hypoxic bottom water. Sea-level fall, nutrient decrease and salinity increase in marginal part of basin due to decreased continental runoff caused by aridification was suggested for post-MECO cooling interval. Clastic-carbonate system of the warming period and thermal maximum was changed to only carbonate system of cooling post-MECO period.