Early-Middle Eocene Nummulites and isotope stratigraphy from the Nile Valley and Bahariya Oasis, Egypt

A review of the Nummulites in collections from Eocene limestones in Egypt identifies eighteen distinct species. including four that are recognized here as new: Nummulitesminiaensis, N. benihassani, N. shurafaensis and N . niloticus. Sixteen of these species occur in early to middle Eocene (Ypresian to Lutetian) assemblages from the Minia and Samalut Formations in theNileValley sequence, assigned to the SBZ (shallow benthic zones) 10-12, while two occur in the Bartonian sequence of the Qazzun and El Hamra Formations of Bahariya Oasis, in SBZ 17-18. In order to develop a sound Eocene bio-chronostratigraphy based on accurately identified Nummulites, we correlate the units defined by the Nummulites species described here with standard microfossil biozones based on planktonic foraminifera and calcareous nannoplanoton. Also, in order to understand the time relationship of species in different lineages, the paleoecologic setting of each Nummulites occurrence is correlated with 18O and 13C stable isotope analysis.