High-resolution ostracode records of the paleocene/eocene transition in the South Eastern Desert of Egypt — Taxonomy, biostratigraphy, paleoecology and paleobiogeography

Abstract

Two high-resolution records (Gebel Duwi and Gebel Aweina, southern part of the Eastern Desert, Egypt) across the Paleocene/Eocene boundary were investigated for their ostracode contents. We particularly focused on the taxonomy, biostratigraphy, paleoecology and paleobiogeography of the ostracode assemblages and on the question whether there was a relationship between faunal and environmental changes associated with the Paleocene/Eocene thermal maximum (PETM). The two sections yielded a total of 29 different taxa, 19 in Duwi and 17 in Aweina, respectively. Four species,Cytherella aegyptopunctata, “Bairdia” malzi, Alocopocythere schmitzi andAegyptiana duwiensis are newly described. The ostracode fauna recorded in Aweina reflects outer neritic deposition, whereas the fauna at Duwi represents a middle neritic environment. Among the many taxa first appearing close to the Paleocene/Eocene boundary in Aweina and/or Duwi, onlyLeguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata andCytherella aegyptopunctata were not observed below the interval of the PETM in Egyptian sediments. During the latest Paleocene, some of these taxa migrated from West African basins, possibly through the Trans-Saharan Seaway. Just a few taxa disappeared during the PETM:Reticulina lamellata, Alocopocythere schmitzi andAegyptiana duwiensis. The Paleocene/Eocene boundary interval is also marked by enhanced aggradation and degradation inParacosta species, possibly resulting from lowered oxygen and/or enhanced food levels. These faunal and environmental shifts were controlled by a complex interplay between oceanographic, climatic, and sea-level changes.