Sequence stratigraphy of the Paleocene succession in the Kharga Oasis, Western Desert, Egypt: insights from microplankton biostratigraphy and benthic foraminifer paleoenvironments

Abstract

The present work provides a comprehensive stratigraphic consideration for the Paleocene (Danian–early Thanetian) succession in the Gebel El-Teir section, Kharga Oasis, Western Desert. The study incorporates calcareous nannofossils, foraminifers (planktic and benthic), and microfacies analyses to deduce fluctuations in the relative sea level and construct a sequence stratigraphic framework. In terms of the microplankton biostratigraphy, five planktic foraminifer (P2, P3a, P4a, P4b, and P4c) and four calcareous nannofossil (NP4–NP6 and NP8) zones have been recognized. Moreover, three biostratigraphic hiatuses were recognized based on the integration between the calcareous nannofossil and planktic foraminifer bioevents. These hiatuses aided in subdividing the studied interval into four 3rd order depositional sequences (D-DS1, S-DS2, S/Th-DS3, and Th-DS4). The paleo-water-depth variations deduced from the foraminiferal and sedimentological proxies facilitate the establishment of a relative sea-level curve and, subsequently, the systems tracts of each depositional sequence were readily recognized. The shallowest water conditions (middle neritic setting) occurred during the deposition of the Danian interval. However, a much deeper paleoenvironment (deep outer neritic-upper bathyal settings) marks the Selandian/Thanetian (S/Th) transition interval. The proposed sequence stratigraphic model and the presence of some extended hiatuses attribute the primary cause for accommodation destruction/creation to the regional tectonic uplift/subsidence. However, once the basin had been formed, the relative sea level within the individual depositional sequence behaved in a manner consistent with the contemporaneous eustatic 3rd-order transgression and regression events.