The global Campanian-Maastrichtian stage boundary

The Campanian-Maastrichtian boundary has never been formally defined; in addition to a number of other less common uses two current practices exist: they consider the first occurrence (FO) of the boreal endemic key taxon Belemnella lanceolata (belemnite) and the last occurrence (LO) of the oceanic Radotruncana calcarata (planktonic foraminifera). Based on indirect correlation, the boreal FO is distinctly younger compared to the Tethyan LO. The Tethyan section near Dax (Tercis les Bains*, SW France) has been studied in detail for the last eight years by a Maastrichtian Working Group. Physicochemical data and biostratigraphical characterisation on 18 fossil groups have been established. The selected section is exceptionally well located in a key area allowing correlation between the Boreal and Tethyan Realms, western Europe and North America, the oceanic and platform environments, the marine and continental successions. Correlation with regard to historical stratotypes of Charente (France) and Limburg (Belgium and the Netherlands), key sections in the Boreal (mostly Kronsmoor, N. Germany) and Tethyan Realms (mostly Navarra, N. Spain and Gubbio, Apennines) have been studied and discussed. The here-presented boundary point is consistent with the content of historical stratotypes; a rather precise connection with the records in the Apennines and N Germany allows to locate the Tercis boundary in these two areas and, reversely, to correlate stratigraphical information from these areas to the Tercis section near Dax. The new definition was voted and ratified between 1999 and 2001.