Sea-level changes in the Paleocene (Danian–Thanetian) succession at the Dakhla Oasis, Western Desert, Egypt: implications from benthic foraminifera

Abstract

The Danian–Thanetian benthic foraminiferal assemblages at the Gharb El-Mawohb section in the Dakhla Oasis of Western Desert (Egypt) are inferred in combination with characteristic species, genera distribution, Benthic Foraminifera Numbers (BFN), species diversity, and abundance of high flux-species to infer prevailing paleoenvironment, paleoproductivity and paleobathymetry vis-à-vis sequence stratigraphy, regional tectonics, climate and changes in sea-level. The response of benthic foraminiferal assemblages to sea-level changes during boundary successions, namely the Danian/Selandian (D/S) and the Selandian/Thanetian (S/Th) is also analyzed. Data suggests a remarkably highly equitable environment throughout the studied interval. Eighty eight percent of the data plot in the restricted littoral environment (mostly in brackish and some in normal lagoons) suggesting that the fauna are not stressed despite a largely shallow depositional setting (middle to outer neritic, at places upper bathyal). The dominance of calcareous taxa indicates a largely open marine condition, in a largely oxic and oligotrophic environment, except in the late Paleocene where high-organic-flux species suggest increased paleoproductivity possibly due to local upwelling. The end of Zone P2 marks the deepest part of the studied section (outer neritic to upper bathyal) followed by gradual shallowing across the section (inner to middle neritic), with intermittent deepening in the middle of Zone P3a and P3b (middle neritic). There is shallowing at the transitions of Zones P3a, P3b and P4 (inner neritic). The changes in the vertical facies and benthic foraminiferal assemblage at the D/S and S/Th boundaries are analyzed.