Variations in Calcareous Nannofossil Assemblages and paleoenvironmental studies on the Danian – Selandian Succession at the Qreiya area, East Qena, Eastern Desert, Egypt

Abstract

Calcareous nannofossil biostratigrapgic and paleoenevironmental studies were carried out on a 20 m of the Paleocene Dakhla Formation at the Qreiya section (East Qena, Eastern Desert, Egypt). The Late Danian Event (LDE) bed was included in this study. Four zones (CNP4, CNP5, CNP6 and CNP7) and two subzones (CNP5a and CNP5b) were delineated according to the zonal scheme of Agnini et al. (2014). Several species were suggested as new ones that belong to genera Diantholitha, Lithoptychius, Pontosphaera and Lapideacassis. The biostratigraphic significances of Chiasmolithus edentulus, Sphenolithus primus, Diantholitha sp. Lithoptychius sp., Prinsius spp., Braarudosphaera bigelowii as well as radiative episodes of fasciculiths were discussed in this research. The Danian-Selandian boundary is tentatively traced within Zone CNP7. Calcareous nannofossil data suggest mesotrophic and cool-water conditions during most of the study interval. However, warm-water conditions prevailed the lower part of this interval as well as the basal part of the LDE interval.