The position of the Montian Stage and related facies within the stratigraphic-palaeogeographic framework of NW Europe during the Danian

A revision of the status of the Danian and Montian Stages based on available biostratigraphic data for their stratotypes, shows that the Montian is the age-equivalent of part of the Danian and should consequently not appear on the standard global stratigraphic chart. The Early Palaeocene of the Paris Basin is characterised by two diachronous units, viz. the Mont Aimé-Vertus Formation of Early Danian age, and outcrops exposing the ’Calcaire pisolithique’, at e.g. Vigny, Laversines, Meudon, which are coeval with the stratotypical Montian, and of Middle Danian age. Two successive Danian transgressions are distinguished in the Paris Basin. The biohermal and bioclastic sediments were deposited in marine environments of shallow (a few metres, 30 m at the most) and warm (+18 to +20°C for the coolest month) water and distributed along the pattern of a carbonate ramp.