Early Paleogene calcareous nannofossil and planktonic foraminiferal biostratigraphy in Central Egypt

The study of calcareous nannofossils and planktonic foraminifera in five Lower Paleogene stratigraphic successions: El-Shaghab, El-Homra El-Shanka (Esna area); El-Sheikh Eisa (East of Qena); Umel-Ghanayem, and Teir/Tarawan (Kharga Oasis) has proved to be a useful tool in biostratigraphic subdivisions. The zonal boundaries were determined and the recorded biostratigraphic zones are in harmony with those proposed by different authors. Meanwhile, the recognized biozones are, to a great extent, similar to those established in the stratotype sections. The Early Paleocene / Late Paleocene boundary is located at the first appearance datum (FAD) of Morozovella angulata especially at G. Umel-Ghanayem and within the nannofossil Zone Ellipsolithus macellus (NP4) at the other sections. The most important event during the Paleocene is the first appearance of the genera Fasciculithus and Sphenolithus in the upper NP4 Zone that, subsequently gave rise to Heliolithus and Discoaster. The Paleocene/Eocene transition is delineated at the base of the Tribrachiatus contortus Zone (NP 10) in the G. El-Homra EI Shanka and G. El-Shaghab sections, and in the top part of the Discoaster multiradiatus Zone (NP9) in the other sections. This boundary is also located at the extinction level of the foraminiferal species Morozovella velascoensis. An evolutionary sequence linking Tribrachiatus bramlettei, T. contortus and T. orthostylus is also demonstrated within the nannofossil Zone NP10. The abundance of discoasters, sphenoliths, and pontosphaers in the Upper Paleocene and Lower Eocene sediments may reflect some changes in climate and warming of the surface waters during this time.