Upper Campanian-lower Maastrichtian integrated carbon isotope stratigraphy and calcareous microplankton biostratigraphy of North-central Tunisia

A comprehensive stratigraphic framework is presented for the upper Campanian-lower Maastrichtian succession of the Elles section in North-central Tunisia. This has been done by applying an integrated approach including calcareous nannofossil and planktonic foraminiferal biostratigraphy in conjunction with carbon isotope stratigraphy. The studied interval spans from the Uniplanarius sissinghii (CC21) to Reinhardtites levis (CC24) calcareous nannofossil zones and their coeval planktonic foraminiferal zones from the Contusotruncana plummerae Zone to Planoglobulina acervulinoides Zone. Seven positive and negative delta C-13 events have been recognized and considered for high-resolution global correlation. Isochroneity and diachroneity of the microplankton bioevents regarding the carbon isotope stratigraphy were assessed. Some discrepancies were reported, and some of them denote actual diachronism. However, the impact of the different taxonomic concepts and/or environmental issues cannot be totally excluded. The Campanian/Maastrichtian boundary has been precisely positioned within the lowermost part of the El Haria Formation at the base of the delta C-13 event CMBc (72.15 +/- 0.05 Ma). This level projects directly below the first occurrence of the planktonic foraminifer Gublerina cuvillieri and about 9.4 m below the last occurrence of the nannofossil Uniplanarius trifidus.