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RESEARCH PRODUCT

Late Cretaceous changes in continental configuration: toward a better-ventilated ocean?

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International audience; Oceanic anoxic events (OAEs) are large-scale events of oxygen depletion in the deep ocean that happened dur-ing pre-Cenozoic periods of extreme warmth. Last global OAE occurred at the Cenomanian-Turonian boundary(OAE2) prior to the Late Cretaceous long term cooling. Ever since, and despite the occurrence of warming events,Earth no more experienced such large-scale anoxic conditions. Here we explore the role of major continentalconfiguration changes occurring during the Late Cretaceous on oceanic circulation modes through numerical sim-ulations using a General Circulation Model (GCM), that we confront to existing neodymium isotope data ("Nd).Except from a continuous deep-water production in the North Pacific, the simulations at 95 Ma and 70 Ma revealmajor differences marked by a shift in the southern deep-water production sites from South Pacific at 95Ma toSouth Atlantic and Indian oceans at 70Ma. Our modelling results support an intensification of southern Atlanticdeep-water production as well as a reversal of the deep-water fluxes through the Caribbean Seaway as the maincauses of the decrease in"Nd values recorded in the Atlantic and Indian deep waters during the Late Cretaceous.We conclude that the change from a sluggish to a much more active circulation depicted by the model in theAtlantic from 95Ma to 70Ma may have driven the disappearance of OAEs after the Late Cretaceous.