Calcareous nannofossil biostratigraphy and paleoecology of the Maastrichtian– Paleocene deposits in southern Tethys: “a case study from the upper Nile Valley (NE Africa)”

Abstract

The current study focuses on the biostratigraphy and paleoecology of calcareous nannofossils within the Maastrichtian–Paleocene sequences of southern Tethys, specifically in three land sections of the upper Nile Valley of Egypt (NE Africa). The sections (from north to south) are Gabal El-Borga, Gabal El Sharawna, and Gabal El Nezzi sections. The sequence was represented by the Dakhla, Kurkur, Tarawan, Garra, and Esna formations. The main goal is the biostratigraphy and Paleoecology of calcareous nannofossils within the Maastrichtian - Paleocene of southern Tethys, specifically in three land sections of the upper Nile. Examination of calcareous nannofossils resulted in the identification of 40 species of 30 distinct genera. The biostratigraphic analysis of the calcareous nannofossils was summarized as follow: CC23, CC24, CC25 (Maastrichtian) and NP2, NP3, NP4, NP5, NP6, NP7/8, NP9 (Paleocene). The NP4 Zone was divided into six zones and subzones (NTp6, NTp7A, NTp7B, NTp8A, NTp8B, and NTp8C). Absences of CC26 and NP1 biozones refer to a hiatus between the Cretaceous/Paleogene (K/Pg) interval. The Danian–Selandian boundary is characterized by the appearance of Lithoptychius ulii, L. pileatus, and L. janii, which marks the second radiation of Fasciculithus. Maastrichtian in the study area was characterized by tropical flora, which indicates low surface water fertility. Taxa from warm-water oligotrophic habitats were prevalent in the Paleocene stratigraphic sequences of the research region.