Interprétations nouvelles sur les relations entre calcarénites et calcaires à rudistes du Barrémien inférieur dans le Vercors méridional (sud-est de la France)

This work is focused on the limestones with rudistids (Monopleuridae and Requienidae of the lower Barremian and the base of the upper Barremian, essentially) of southern Vercors. It is particularly focused on the relationships, which exist between this facies and the Barremian calcarenites of this area. The geological logs we have constructed, and our photographic panoramas show that the pattern of the deposits is repetitive and indicates, for the calcarenites, a decrease of the hydrodynamism, which can be interpreted as the result of an increase of the accommodation. The underlying rudistids limestones, which settle before marls, or argillaceous limestones, seem to be included in a transgressive context. It is also shown that: 1) these two deposits are synchronous since they follow each other; and 2) the rudistids limestones, in the studied area, are never protected by a barrier. So, the rudistid limestones of southern Vercors can be considered as deposits settling during a transgressive period.