Sea-level fluctuations during the Danian-Selandian interval in Sinai, Egypt: Insights from benthic foraminiferal biofacies analysis

Abstract

The Paleocene hemipelagic deposits of the Dakhla Formation in Sinai offer an ideal setting to investigate paleoenvironmental fluctuations using benthic foraminifera. This study examined a Danian-Selandian sedimentary succession at Themed, Sinai using quantitative foraminiferal analysis within a sequence stratigraphic framework. Quantitative multivariate analyses, including R-mode clustering and non-metric multidimensional scaling (NMDS) ordination of biofacies trends and diversity parameters, indicate considerable paleoenvironmental and paleobathymetric changes throughout the studied succession. Five transgressive-regressive (T-R) sequences were identified based primarily on benthic foraminiferal biofacies trends. The sequence boundaries correlated well with major global sea-level lowstands. Benthic foraminiferal assemblages elucidated paleobathymetry fluctuations between upper bathyal and middle-outer neritic settings across the sequences. The identified sequences strongly correlate to global eustatic cycles, with subtle disparities suggesting a subordinate role for regional tectonics overprinting the dominant sea level control. The Latest Danian Event (LDE) interval coincides with the regressive phase of the fourth T-R sequence, as revealed from the biostratigraphic-constrained isotopic signature. It showed pronounced peaks in the relative abundance of the eutrophic buliminids, likely reflecting enhanced export productivity. Overall, benthic foraminifera provided vital paleoenvironmental insights, enabling sequence stratigraphic interpretation in the monotonous hemipelagites and highlighting possible coupled dynamics of both the carbon cycle and sea level.