Towards aGSSP proposal for the base of the Albian Stage at Col de Pré-Guittard (Vocontina Basin, southeast France)

A detailed study across the Niveau Kilian black shale in the Col de Pré-Guittard section (Vocontian Basin, southeast France) well documents an abrupt planktonic foraminiferal turnover and a negative δ13C shift across the Aptian–Albian transition. Stratigraphically ordered events relative to the base of the Niveau Kilian include: (1) appearance of the calcareous nannofossil Praediscosphaera columnata (circular form) and Helicolithus trabeculatus at -8 m; (2) extinction of Paraticinella eubejaouaensis at -2.25 m and of all late Aptian planktonic foraminifera species between -3.0 and -0.2m; (3) appearance of the small planktonic foraminifera Microhedbergella miniglobularis at -2.0 m; (4) onset of a 1‰ negative δ13C excursion at -1 m; (5) minimum δ13C values between +0.3 and +0.6 m; and (6) appearance of the small planktonic foraminifera Microhedbergella renilaevis at +0.4 m. The succession falls within the upper part of the ammonite Hypocanthoplites jacobi Zone. Reports of the same sequence of planktonic foraminifera and δ13C events from deep-sea sites in the North and South Atlantic and Indian Oceans demonstrate that they can be globally correlated. We propose that the GSSP for the base of the Albian Stage be defined at the lowest occurrence of Microhedbergella renilaevis where δ13C values are at their minimum.