The early Valanginian and the Barremian-Aptian boundary time intervals

With this project, we perform research on two key intervals of environmental change in the shallow-water platform succession of the northern Tethyan helvetic realm, during which the predominantly photozoan carbonate-producing community changed towards a heterozoan carbonate-producing community. These intervals are dated as early Valanginian and the Barremian-Aptian boundary time interval. The early Valanginian is characterized by important paleoenvironmental and paleoceanographic change, which is amongst others expressed by a pronounced positive carbon isotope excursion, whereas the Barremian-Aptian boundary time interval distinguished by a negative excursion in stable carbon isotopes. We analyze a representative selection of key sections in the helvetic realm, which are complemented with well-preserved sections in SE France. The sections will be analyzed with regards to their mineralogy, facies and microfacies, sedimentology, sequence stratigraphy, geochemistry, and paleontology. The geochemical analyses will consists in stable carbon and strontium isotope analyses, redox-sensitive trace-metal concentrations, phosphorus contents, and organic carbon contents.