Author:

Keywords:

Egypt, excursion, Leuven, Sea level, Geochemistry & Geophysics

Abstract:

A study on Danian to Selandian foraminifera (planktic/benthic ratios, benthic assemblages) in 23 sections on a N-S transect in eastern Egypt documents a transient biotic excursion associated with sea-level fluctuation at ∼60.5 Ma (Subbiochron P3a). In southern areas, the inner to middle neritic (30–70 m) Neoeponides duwi assemblage expanded into deeper parts of the shelf (∼70–250 m), temporarily replacing the Anomalinoides umboniferus and Angulogavelinella avnimelechi assemblages. In the deeper parts of the basin (∼400–600 m) in the northern part of the transect, the Gavelinella beccariiformis assemblage appears to have been persistent throughout the studied time interval. Biofacial and sedimentologic data suggest a relative sea-level fluctuation, possibly with an amplitude of 50–100 m, which may correlate with a eustatic sea-level cycle during the Danian-Selandian transition. During early sea-level rise, total organic carbon–enriched, partially laminated sediments, containing abundant fish-remains and planktic foraminifera (>99.5% planktics), were deposited, reflecting oxygen deficiency at the seafloor. The patterns of biotic and sea-level change at the Danian-Selandian transition strongly resemble those across the Paleocene-Eocene Thermal Maximum in the same basin, suggesting similar operative processes. Considering the close coincidence with a recently postulated brief period of oceanic warming at 60.5 Ma, the question arises whether the observed patterns in Egypt could in part be related to a global warming event, similar to the Paleocene-Eocene Thermal Maximum.