Planktonic foraminiferal biostratigraphy of the upper Cretaceous to mid-Paleocene of the Dababiya Quarry Corehole, Upper Nile Valley, Egypt

Abstract

Biostratigraphic studies of planktonic foraminifera on the Dababiya Quarry corehole suggest an eight-fold zonal subdivision of the lower (Dakhla Shale,Danian) and middle (uppermost Dakhla and Tarawan Chalk) Paleocene. Preliminary studies of the basal part of the hole (~137–140 m) and the uppermost Cretaceous (~80–81 m) indicate the presence of the lower Maastrichtian Globotruncana aegyptiaca and upper Maastrichtian Pseudoguembina palpebra Zones, respectively. It would appear that there is a short hiatus at the Cretaceous/Paleocene boundary (denoted by the P. palpebra/Parvulorugoglobigerina eugubina zonal boundary and apparent absence of the (uppermost Maastrichtian) Pseudoguembelina hantkeninoides Zone and the (basal Danian) Guembelitria cretacea (P0) Zone, which may be due to syn-sedimentary tectonic and/or inadequate sampling density. The Danian/Selandian (D/S) boundary is placed at the boundary between the Igorina albeari/Praemurica carinata (=lower part of Zone P3b) Zone and the Ig. albeari (=upper part of Zone P3b) Zone at a distinct phosphatic bed tentatively correlated with the Qreiya Bed (in the Qreiya section) and the “Neo-Duwi Event" at 44.5m. This bed is marked by the gradual disappearance of praemuricid taxa in general and the lowest occurrence of P. carinata in particular.