The results of previous research carried out by the members of the team throughout the Lower Cretaceous led to the proposal of new objectives and scientific challenges in relation to the multidisciplinary study of the interval between the upper part of the Lower Barremian and the Lower Aptian. The main objectives of this project have not been addressed so far by any other international research team
PY20_00783 Research Project
Events around the Barremian / Aptian boundary
The problematic around the Barremian/Aptian boundary
Currently, the boundary between the Barremian and Aptian Stages (standard chronostratigraphic units) is provisionally located at the base of the CM0r magnetochron, as agreed at the Second International Symposium on Cretacous Stage Boundaries (Brussels, 1995). This designation was made on the basis of the supposed proximity of the lower boundary of CM0r to the first appearance of deshayesitid ammonites (Prodeshayesites), which is considered as the base of the Aptian by ammonite specialists (e.g., Reboulet et al., 2018) . Subsequent investigations have shown that the CM0r base is located within the upper Barremian, being quite below the first appearance of deshayesitids. In addition, the magnetostraigraphic record is very poor in the hemipelagic sections where ammonite stratigraphy has been established, preventing their direct correlation. At this time, it is being discussed by the Aptian Working Group (AWG) of the International Subcommission on Cretaceous Stratigraphy which may be the best event to be used as Barremian / Aptian boundary at a global scale. Several researchers of our team are members of the AWG, hence one of the objectives of the current project is the accurate determination of the events (biological and geochemical) along the upper part of the Barremian and the lower part of the Aptian. This knowlledge will provide the scientific community with the information needed for choosing the most appropriate event to be used as the Barremian / Aptian boundary.