Abstract
Two upper Palaeocene – lower Eocene stratigraphic sequences at the Kharga Oasis (Umm El Ghanayim and Naqb Assiut sections) were studied biostratigraphically on the basis of their calcareous nannofossil content. The investigated interval includes the upper part of the Tarawan Formation, the Tarawan Chalk, and the Esna formations. A total number of sixty-seven different taxa have been identified. The lowest occurrence (LO) of Discoaster araneus was used to place the base of the NP9b Subzone (base of Eocene) at the Gabal Umm El Ghanayim section. The lowest occurrences (LOs) of Rhomboaster bitrifida, Discoaster araneus and D. anartios are used to define the NP9a/NP9b subzonal boundary at the Gabal Naqb Assiut section. In this section,the P/E boundary is marked by a minor lithologic hiatus as indicated by the absence of the basal part of the Dababiya Member.At the studied two sections, a major turnover in calcareous nannofossil assemblages across the P/E transition was documented. The abundance of warm water Ericsonia subpertusa, Fasculithusspp., Coccolithus eopelagicus, Discoaster spp., Rhomboaster bitrifida and Tribrachiatus bramlettei characterize the Palaeocene-Eocene transition and suggest global warming and the Palaeocene – Eocene Thermal Maximum (PETM).
Highlights
The late Palaeocene to early Eocene interval is considered to be one of the warmest time periods (THOMAS, 1998) known as the Palaeocene – Eocene Thermal Maximum (PETM) (KENNETT & STOTT, 1991) during which numerous events occurred
This interval is marked by the mass extinction of benthic foraminifera, with a global decrease in their diversity, which ranges from 30 to 50% (KENNETT & STOTT, 1991), be ing known as the Benthic Foraminiferal Extinction Event (BFEE) (THOMAS & SHACKLETON, 1996)
Calcareous Nannofossils Biostratigraphy The present manuscript concerns the biostratigraphy of calcare ous nannofossils from the upper part of the Tarawan Chalk and Esna formations at the Umm El Ghanayim and Naqb Assiut sections
Summary
The late Palaeocene to early Eocene interval is considered to be one of the warmest time periods (THOMAS, 1998) known as the Palaeocene – Eocene Thermal Maximum (PETM) (KENNETT & STOTT, 1991) during which numerous events occurred. Major changes in the terrestrial and marine biota occurred at the PETM. This interval is marked by the mass extinction of benthic foraminifera, with a global decrease in their diversity, which ranges from 30 to 50% (KENNETT & STOTT, 1991), be ing known as the Benthic Foraminiferal Extinction Event (BFEE) (THOMAS & SHACKLETON, 1996). The extreme environmen tal changes at the PETM caused those malformations of coccoliths (JIANG & WISE, 2006). The global Palaeocene/Eocene bound ary was defined at the Dababiya Quarry section, south of Luxor, in the Upper Nile Valley (DUPUIS et al, 2003)
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