Biostratigraphy and depositional environments of thePalaeocene–Eocenesuccession at Um El Huwaitat area, Eastern Desert, Egypt

Abstract

The Palaeocene-Eocene succession in southwest Safaga, Eastern Desert, Egypt has been studied to determine its lithostratigraphic units, biostratigraphic zonation, microfacies association, and depositional environments. The variation in lithofacies allows the subdivision of the Danian-Ypresian interval into four lithostratigraphic units that are arranged, from base to top, as the Dakhla Shale (only its upper part), Tarawan Chalk, Esna Shale, and Thebes Formation (only its lower part). Moreover, the Esna Shale is further subdivided into four members, arranged from base to top, as El Hanadi, Dababiya Quarry, El Mahmiya, and Abu Had. The depositional setting is interpreted to primarily reflect the relative sea-level changes. The planktonic/benthic (P/B) foraminiferal ratio is indicative of oscillations of depositional settings in normal open marine conditions, ranging from shallow inner to outer neritic environments. Biostratigraphically, the Palaeocene-Eocene succession in the studied area is subdivided into 12 biozones and subbiozones. These are correlated with the standard biozonation of the Palaeocene-Eocene. Deposition of the Palaeocene-Eocene succession in the studied area took place on a relatively stable shelf. Three lithofacies were recognized: shale, marl, and limestone. The shale lithofacies is differentiated into two sub-lithofacies; pure shale and calcareous foraminiferal shale, whereas marl lithofacies contains abundant planktonic foraminifera. The encountered carbonate rocks comprise eight microfacies types. In addition, the studied interval is correlated with the Global Standard Stratotype Section and Point in the Dababiya section, south of Luxor, Egypt.