Caractères et évolution des plates-formes carbonatées périvocontiennes au Crétacé inférieur (France Sud-Est)

Abstract

The Valanginian to Lower Aptian of SE France is characterized by carbonate platforms referred to the Urgonian (N subalpine massifs, Ardèche and Gard, Provence) which girdle the Vocontian basin, western extension of the deep alpine sea. Facies analysis indicates progressive, though discontinuous, colonization of hemipelagic Vocontian areas from several sources: one of these existed in the Berriasian of Basse-Provence and another in Bas-Dauphiné and Jura. The first persisted throughout the Early Cretaceous while the second disappeared during the Hauterivian. Bioclastics accumulated in Early Barremian time in S Vercors and Ardèche; they initiated a vast extension of platform carbonates at the expense of the hemipelagic facies in the Vocontian region. The largely regressive sedimentary developments depended partly on the synsedimentary interactions of basement faulting; they were marked by short halts and retreats. Three of the discontinuities have regional stratigraphical significance in SE France. The rudist limestones (Urgonian s.str.) reached their maximum extent in the Early Aptian. The accumulation of detritic carbonates ceased with the disintegration of the platforms. Terminal Bedoulian and Gargasian marls were succeeded by a restricted platform environment in the Clansayesian with the accumulation of local bioclastic limestones (Provence) until Early Albian times.