Ocean current intensification during the Cretaceous oceanic anoxic event 2-evidence from the northern Tethys

Mesozoic Oceanic Anoxic Events (OAEs) are expressions of major physical oceanographic changes at times of perturbation of the global carbon cycle. A northern Tethyan record of OAE2 is preserved in expanded Cenomanian-Turonian pelagic limestone sections (Seewen Formation) in Eastern Switzerland. The new carbonate carbon-isotope stratigraphy extracted from these limestones demonstrates that the OAE2 is condensed in all the studied successions and only the onset of the C-13 excursion (5.0 parts per thousand) is present. The condensed interval is characterized by dissolution features, which are filled by a glauconite quartz sandstone. This bed is overlain by a well-sorted sandstone with intercalated limestone pebbles (Gotzis Member), which can be compared with palimpsest sands forming today along current-swept shelves. The wide distribution of this thin sandstone layer within OAE2 indicates that an intense, erosive, east-west trending shelf current was active during the highest sea level and most extreme carbon-cycle perturbation of the OAE2.