Pliocene–Pleistocene bioevents, sequence biostratigraphy and paleoenvironment of the Mediterranean North Delta Basin, Egypt

Integrated high-resolution biostratigraphic approach including foraminifera, nannoplankton and palynomorphs as well as logging data are the main contribution to delineate the age assessment and hydrocarbon reservoirs of the Pliocene–Pleistocene succession of the offshore Delta Basin. The palynological data adds considerable further justifications for positioning sequence elements and interpreting the depositional environment. Three dinoflagellate cyst assembelages are identified and chronstratigraphically calibrated with the foraminiferal fingerprints. Six foraminiferal bioevents are recognized: Acme Sphaeroidinellopsis and last occurrences (LOs) of Globoturborotalita nepenthes, Globorotalia margaritae, Globorotalia puncticulata, Sphaeroidinellopsis, Globigerinoides extremus and first occurrence (FO) of Hyalinea balthica. With the use of the new constrained chronostratigraphic architecture and high-resolution biostratigraphic data, unconformities and system tracts throughout the basin may be more accurately described and correlated. Seven cycles in the stratigraphic architecture were identified, which helps to better describe the reservoir heterogeneity. Facies distribution and development were controlled by global eustatic change, being accompanied by local tectonics. Benthic biofacies, foraminiferal diversity, dinoflagellate assemblage and nannoplankton paleoecological markers indicate a deepening of the basin, interrupted by slope channels during the early Pliocene. The turnover in the abundance of nannoplankton and foraminiferal markers shows sea-level drop during the late Pliocene and Pleistocene epoch.