Abstract

We describe the planktonic foraminiferal biostratigraphy of the ~130m thick upper Paleocene-lower Eocene composite stratigraphic section at Dababiya, which contains the recently designated Global Standard Stratotype Section and Point (GSSP) of the Paleocene/Eocene boundary. The measured (composite) section extends from the Tarawan Chalk (Zone P4), through the Esna Shale (Zone P4c, P5-8) to the basal Thebes Limestone (Zone P8). Midway-type benthic foraminiferal faunas extend throughout the section and suggest deposition at mid-outer neritic depths with no indication of (significant) shallowing at the Esna/Thebes contact across which Zone P8 planktonic foraminiferal faunas continue. The Paleocene/Eocene boundary GSSP is located in the lowermost part of the Esna Shales at the base of a dark clayey horizon at ~1.6m above the base of section DBH (~5.7m above the top of the Tarawan Chalk). The level is firmly located in conjunction with the base of the carbon isotope excursion (CIE) and is immediately succeeded by ~3.75m of the lithologically distinct Dababiya Quarry Beds. The characteristic planktonic events that are associated with the CIE in oceanic sections are well represented throughout the 3.2m interval directly overlying the P/E GSSP (~5.7m to 8.9m above the base of the Esna Shales) within the Dababiya Quarry Beds. Acarinina sibaiyaensis is by far the most common of the planktonic foraminiferal excursion taxa (PFET) that appear slightly (75cm) above the base of the Dababiya Quarry Beds. The latter interval exhibits a phased pattern characterized by different lithologies, biota and faunal patterns that we interpret as reflecting progressive changes in temperature and content of dissolved oxygen as a result of global changes in climate and water circulation. The critical interval is generally bracketed (below) by the upward sequential lowest occurrences (LOs) of Acarinina esnaensis, Igorina broedermanni, Ac. angulosa and Ac. wilcoxensis, and (above) by the LO of Pseudohastigerina wilcoxensis.

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