Foraminiferal biostratigraphy and paleoenvironments of the Danian-Selandian succession at the Kharga Oasis, Western Desert, Egypt

Abstract

The present work deals with the foraminiferal investigations and analyses of the Danian-Selandian (D-S) succession at Naqb El-Rufuf and Umm El-Ghanayim sections in the Kharga Oasis. Five planktonic foraminiferal zones and subzones (P1c, P2, P3a, P3b, and P4a) were recognized within the studied sections. The D/S stage boundary is characterized by a faunal break at the P3/P4 zonal boundary owing to completely or partially absence of the P3b subzone. This hiatus reveals the dual signature of both the eustatic sea-level changes and the regional tectonic event of the Syrian Arc System. The studied interval is subdivided into three transgressive-regressive sequences bounded by three sequence boundaries at the Cretaceous-Paleogene (K/Pg.) boundary, the boundary between P3a/P3b subzones and the D/S boundary, respectively. The D/S transition is associated with substantial changes in the structure and composition of the foraminiferal assemblages point to extensive paleoenvironmental turnover. The latest Danian sediments were deposited under deep inner-shallow middle neritic environments with oxygen-depleted bottom water conditions and increased trophic level, where an outer neritic environment with meso-oligotrophic and well-oxygenated bottom water conditions prevailed during the deposition of the Selandian deposits.