Planktonic Foraminiferal Evidence of Upper Cretaceous in the Well “A” (Gulf of Hammamet Area, Northeastern Offshore Tunisia)

Abstract

The gulf of Hammamet area, lying in the extreme northeastern offshore Tunisia, is characterized by several discontinuities through the Mesozoic and Cenozoic series. These discontinuities had affected the thickness distribution of deposited sequences in the area such as the El Haria Formation (Fm.), which is supposed in the literature to be locally, partially or totally eroded. A number of geological works based on geophysics, seismic and log data in the Gulf of Hammamet area consider the existent part of the El Haria Fm. as a whole sequence, attributed to the Palaeocene when it is partially eroded. Hence, the focus on the planktonic foraminiferal stratigraphic range in the present work revealed the existence of a Late Cretaceous unit of the El Haria Fm., spanning ~25 m of marls overlying the limestones of the chalky and fractured Abiod Fm. This does not exclude the existence of discontinuities that can affect the Abiod-El Haria interval but confirms the existence of a Late Campanian unit (First Downhole Occurrence of Radotruncana subspinosa) that can probably be unconformably overlaid by a Late Maastrichtian unit (First Downhole Occurrence of Late Maastrichtian foraminifera).