Biostratigraphic implications of the Valanginian to Lower Hauterivian benthic foraminifers from the Vergol/La Charce composite Section (southeast France, Vocontian Basin)

Abstract

The well-exposed Valanginian to Lower Hauterivian sequences of the Vocontian Basin (South-East France) are revisited based on a micropalaeontological study of material collected in the Vergol and La Charce sections. A total of 528 tests of benthic foraminifers were recorded in good state of preservation. A biometric analysis of the species Dorothia hauteriviana is proposed in order to identify its morphotypes and their biostratigraphic significance. This study aims to identify benthic foraminiferal assemblages and to propose an integrated biostratigraphy along the Valanginian to Hauterivian sequence of the Vergol and La Charce sections (Vocontian Basin). Two foraminiferal assemblages have been recognized. The Lenticulina nodosa foraminiferal assemblage ranges from the lower Valanginian to the basis of the upper Valanginian Saynoceras verrucosum ammonite standard zones (StZ). The Lenticulina busnardoi foraminiferal assemblage is recorded from the second half of S. verrucosum to the top of Neocomites peregrinus StZ. The current study shows that the Vergol and La Charce composite section represents a complete segment of Valanginian to Lower Hauterivian foraminiferal assemblages, and records several changes in taxonomic biodiversity and dynamics of population for this interval.