Late Paleocene-Early Eocene nannofossil bioevents at Gebel El Aguz, Northern Kharga Oasis, Western Desert, Egypt

Abstract

The calcareous nannofossil biostratigraphy of the Paleocene/Eocene (P/E) interval in six sections (NA, NB, NC, NF, NK2, and NK3), in the El Aguz area, Northern Kharga Oasis was carried out and documented for the first time in detail. The studied successions encompass the upper part of Tarawan Formation and the Esna Formation. The Esna Formation is subdivided into four members. These members, from base to top, are the El Hanadi, El Aguz Limestone, El Mahmiya, and Abu Had members. Sixty-six nannofossil species were identified from the Paleocene/Eocene succession in the studied sections which includes nannofossil zones NP9 to NP11. The early Eocene (NP9b) is identified based on the first occurrences of (FO) Discoaster araneus and D. anartios in section NA; the FO of D. araneus in sections NB and NF; the FOs of D. araneus and Rhomboaster spineus in section NC; the FOs of D. araneus, and R. cuspis in section NK2; and the FOs of D. anartios and Rhomboaster bitrifida in section NK3. The Paleocene/Eocene boundary is placed tentatively within the El Aguz Limestone. Extinction and evolution events across the boundary are documented. At section NB, only subzones NP10a and NP10b are recorded within the upper part of the Esna Shale, and the NP11 Zone rests unconformably on Subzone NP10b. The presence of Ericsonia subpertusa, Fasculithus and Sphenolithus taxa suggests that a warm-water environment could have prevailed throughout the P/E transition in the study area.