Decoding the Marine Biohistory of the Late Oligocene – Early Miocene Offshore Nile Delta: Planktonic Foraminiferal Biostratigraphy, Sequence Stratigraphy, and Paleoecology

This study presents an integrated analysis of planktonic foraminiferal biostratigraphy, paleoecology, and sequence stratigraphy from the offshore Nile Delta (Eastern Mediterranean). Based on 54 species identified in the PFDM-2R (BIS) well, eight biozones (O5–O7, M1–M5a) are established, providing a detailed chronostratigraphic framework. For the Miocene interval, biozones are correlated with both the global low-latitude zonation and the Mediterranean Neogene planktonic foraminiferal zonation, providing a regionally calibrated chronostratigraphic anchor for the eastern Mediterranean sub-basin. The Oligocene–Miocene (Chattian–Aquitanian) boundary is defined by the lowest occurrence (LO) of Paragloborotalia kugleri, which approximates the global Mi1 glaciation, anchoring this local stratigraphic transition within a broader narrative of Cenozoic climatic change. Paleoecological analysis indicates profound changes in upper water-column stratification and bioproductivity, likely linked to fluctuations in oceanic currents or Nile River input. Paleobathymetric reconstruction reveals three main transgressive-regressive cycles that show high synchronicity (∼85%) with global eustatic sea-level curves. Sequence stratigraphic interpretation delineates three third-order depositional sequences (DS1–DS3), each comprising transgressive and highstand systems tracts. These results demonstrate eustatic control on regional sedimentation and provide a robust analog for understanding past and future oceanographic changes in the Eastern Mediterranean. The refined sequence stratigraphic model also offers a predictive framework for identifying potential reservoir and seal units in this prolific hydrocarbon province.