Sequence stratigraphy and biozonation of the Upper Eocene Anqabiya Formation, Gebel Anqabiya, Egypt

Few studies on bio-sequence stratigraphy of the late Eocene succession in the study area have published so far. Accordingly, an exposed section of the Anqabiya Formation at Gebel Anqabiya along Cairo-Suez district of Egypt, was examined in detail to determine its foraminiferal and nannoplankton assemblages and to produce a sequence stratigraphic classification. We reveal that in this section, foraminifera and calcareous nannoplankton are generally rare, with relatively poor to moderate preservation, and restricted to certain horizons. Nineteen species of planktonic foraminifera and 24 species of calcareous nannoplankton were identified, leading to the classification of two planktonic foraminiferal zones (Globigerinatheka semiinvoluta Zone E14 and Globigerinatheka index Zone E15) and one calcareous nannoplankton zone (NP19-20). Forty-seven species of benthic foraminifera were identified and quantitatively analyzed to determine changes in paleo-water depth. Three local benthic biofacies, the Elphidium biofacies, the Cibicides biofacies and the Uvigerina biofacies, were recognized, and six microfacies types were distinguished. These analyses indicate that the studied succession was deposited under shallow marine environmental conditions representing a single 3rd-order depositional sequence. The interpreted sea-level curve can be correlated with the global curves during the late Eocene, and the correlation suggests a sea-level rise during E14 Zone, followed by a sea-level fall in E15 zone.