Deep basin record evolution of chemical weathering and physical erosion as response to the tectonic uplift of the South African Plateau during the upper Cretaceous

<p>During the upper Cretaceous the South African Plateau underwent an uneven uplift period that coincided with the onset of a long-term climate cooling. This uplift recorded two pulses, an early pulse during the Turonian that affected the eastern margin and a later pulse occurred during the Campanian affecting the western margin (van der Beek et al., 2002; Braun et al., 2014; Baby et al., 2020). We aim here to determine the response of physical erosion and chemical weathering to this tectonic event, that may have played a role in the long-term climate cooling by promoting silicate weathering and associated atmospheric CO<sub>2</sub> drawdown. In thi…

Hafnium-neodymium isotope evidence for enhanced weathering and tectonic-climate interactions during the Late Cretaceous

<p>Over million-year timescale the carbon cycle evolution is driven by mantle CO<sub>2</sub> degassing (source) and by continental weathering that drawdowns atmospheric CO<sub>2</sub> through silicate weathering reactions (sink). Based on a novel geochemical proxy of chemical weathering intensity (i.e. using measurements of Hf and Nd isotope ratios in clay-size fractions of sediments) and clay mineralogy, we discuss the links between tectonic, continental weathering and climate evolution during the late Cretaceous. That period records the very first step of the last greenhouse to icehouse transition and is concomitant to …

Conditions d'hydrolyse au cours du Lutétien-Bartonien dans le Bassin parisien : apport des forages d'Ussy-sur-Marne et du Tillet

L’évolution des conditions climatiques du Paléogène a donné lieu à plusieurs synthèses régionales et globales. Le Bassin parisien, qui est l’un des bassins historiques pour la connaissance des dépôts cénozoïques, a été paradoxalement peu étudié du point de vue des paléoclimats. Cela s’explique par des affleurements dispersés, combinés à une grande variation des environnements de dépôts alternant entre continental et marin ouvert, et un calage stratigraphique complexe. Si les reconstitutions de températures sont accessibles par les données floro-faunistiques et isotopiques (δ18O), l’évolution des conditions hydriques et leurs conséquences sur la production et le transport des sédiments terri…

Enregistrement du cycle du carbone à la transition Oxfordien inférieur-moyen dans l'est du Bassin de Paris