Astrochronology of the Valanginian-Hauterivian stages (Early Cretaceous): chronological relationships between the Paraná-Etendeka large igneous province and the Weissert and the Faraoni events.

16 pagesInternational audienceThe Geological Time Scale shows large uncertainties on durations and ages of Berriasian to Albian stages (Early Cretaceous), which impact climate and paleoceanographic reconstructions. Here, we provide a new astrochronology of the Hauterivian Stage anchored on (1) recent biostratigraphically well-constrained published radio-isotopic dates, and (2) a previously published astrochronology of the Valanginian Stage. A new duration of the Hauterivian Stage is assessed here at 5.93 ± 0.41 myr. The retained age model, anchored on a latest CA-ID-TIMS U–Pb age from a tuff level in the Hauterivian of the Neuquén Basin (Argentina), dates the base of the Valanginian Stage at − 137.05 ± 1.0 Ma, the base of the Hauterivian Stage at − 131.96 ± 1.0 Ma, and the top of the Hauterivian Stage at − 126.02 ± 1.0 Ma. In addition, the onset of the mid-Valanginian Weissert Event is dated at − 135.22 ± 1.0 Ma and the onset of the Faraoni Event at − 126.73 ± 1.0 Ma. The duration of the mid-Valanginian carbon-isotope excursion, associated to the Weissert Event, is assessed at 5.85 myr, with a rapid phase of increasing δ13C values (0.60 myr), a phase of stable δ13C values (1.48 myr), and smooth decrease in δ13C values (3.77 myr). The calibration provided here highlights that the onset of the activity of the Paraná–Etendeka province and the start of the Weissert Event coincided, suggesting that the Paraná–Etendeka province may have played a major role on the climatic and oceanographic changes during the mid-Valanginian