Climate changes at the Jurassic/Cretaceous transition vs. supra-regional oceanographic processes: Insights from the Vocontian Basin (Clue de Taulanne section, SE France)

Herein are presented the results of a detailed stratigraphic calibration and palaeoenvironmental studies performed in the upper Tithonian–lowermost Valanginian deposits of the Vocontian Basin (SE France), with special attention being paid to the Clue de Taulanne section. Integration of calpionellid biostratigraphy , magnetostratigraphy and δ 13 C stratigraphy, supplemented with regional correlations, enables precise dating of the latest Jurassic–earliest Cretaceous climate and oceanographic perturbations. These are recognized based on sedimentologic (microfacies analyses, clay mineralogy) and geochemical (elemental geochemistry, TOC) investigations. This research confirms that the latest Tithonian–early Berriasian (Tintinnopsella remanei–mid Calpionella elliptica subzones) was marked by a phase of dry climate and elevated burial of micronutrients. Furthermore, the uppermost Tithonian (Remanei/Massutiniana subzonal transition) documents an important palaeoecologic turnover, that is the disappearance of Saccocoma and a switch from radiolarian- to calpionellid-dominated microfacies . The subsequent shift towards humid palaeoclimate conditions at the early/late Berriasian transition was relatively rapid (∼ 0.5 Ma), as evidenced by a significant increase in kaolinite proportion within the mid-Elliptica Subzone (mid M17r magnetozone; latest early Berriasian). Importantly, this major climate change was associated with lowered burial of nutrient-type elements, relative to lithogenic fraction. Collected data not only evidence the relation between the latest Jurassic–earliest Cretaceous climate and oceanographic processes, but also document biotic response to these perturbations. The regional significance of the above findings is evidenced by correlations between different sedimentary zones of the Vocontian Basin (Clue de Taulanne, Berrias, Montclus and Tré Maroua sections), while supra-regional context is provided by comparison with other Alpine Atlantic successions: Transdanubian Range and the Slovenian Basin. • A supra-regional record of J/K paleoenvironmental processes has been obtained. • A switch from arid to humid climate occurred during the late early Berriasian. • Cool and arid climate mode was associated with oceanographic perturbations. • Geochemical record corresponds with changes in microfossil composition.