Upper Paleocene-lower Eocene planktonic foraminiferal biostrati
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摘要

We describe the lithostratigraphy and planktonic foraminiferal biostratigraphy of the upper Paleocene- lowermost Eocene (Zones P4a-P5c) stratigraphic section exposed in a neritic/shelf carbonate setting at Wadi Abu Ghurra in the southern part of the Upper Nile Valley. The 2.5cm thick PETM-correlative interval lacks the phosphatic-coprolitic horizon(s) typical of the Dababiya Quarry Beds to the north, but does contain elements (Acarinina africana, Ac. sibaiyaensis and M. allisonensis) of the planktonic foraminifera excursion taxa (PFET). The PETM-correlative interval is bracketed (below) by the LO of Acarinina esnaensis, Igorina broedermanni, Ac. angulosa and Ac. wilcoxensis and (above) the LO of Pseudohastigerina wilcoxensis. The top of the inferred PETM-interval coincides with the Garra / Dungul formational contact and is marked by an abrupt enrichment in planktonic foraminifera together with a low-diversity benthic foraminiferal association, comparable to those of the calcarenites which terminate the Dababiya Quarry Beds in deeper water sections in the north. Angulogavelinella avnimelechi, together with several long-ranging Paleocene benthic forms, have their HO at the base of the PETM-interval, whereas dimorphic larger foraminifera (Discocyclina, Operculina, primitive Nummulites) have their LO at its top.

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