Paleoclimate Evaluation, Paleodiversity and Paleobiogeography of the Middle-Upper Eocene Foraminifera from north-west Fayum Area, Egypt.

Abstract

This study deals with the investigation of the benthic foraminiferal assemblage from the Middle–Upper Eocene succession that is exposed in the northwest of Fayoum area, Egypt. The studied section is lithostratigraphically described and subdivided into three rock units named from base to top as follow: The Gehannam Formation (Bartonian), the Birket Qarun and the Qasr El-Sagha formations (Priabonian). The examination of fifty rock samples yielded 104 benthic foraminifera species which belong to 31 genera, 23 families, 13 superfamilies and 4 suborders.  The recorded planktonic foraminifera showed rare and scattered occurrences through the studied succession, therefore it does not allow a precise biostratigraphic correlation. The Eocene age of the studied section is assigned based on the co-occurrence of the index small sized planktonic and benthic foraminiferal species. The recorded benthic foraminifers were subjected to cluster analysis to gain insights into the relation between the distribution of the benthicforaminiferal communities and the prevailing paleoenvironmnetal conditions. The observed low Total Organic Carbon (TOC) values of the studied samples could be attributed to either significant high sediment influx or the dominance of high oxygenated conditions. X-ray diffraction (XRD) results show that kaolinite is the dominant clay minerals in the analyzed samples, indicating high chemical weathering during warm and humid greenhouse climatic conditions. The identified species displayed significant resemblances to adjacent regions in the southern Tethys, like Libya, indicating potential migration through the trans-Sahara seaway. However, there were only slight similarities with species found in the northwestern Tethys and the North Atlantic regions. This can be attributed to the benthic nature of these species, limiting their ability to migrate over long distances. Furthermore, it is associated with cooler, latitudinal zoned climatic conditions prevailing along the northwestern Tethys, which did not align with their specific biological requirements.