Bottom current circulation during the Early Cenozoic in the Norwegian-Greenland Sea

Opening and closing of ocean gateways, generally controlled by plate tectonics and temporal changes in magmatism, have a profound impact on deep-water ocean circulation and may play a crucial role in global climate changes. The sediment record, in particular the presence of contourites, provides direct palaeoceanographic information that can be used to constrain the deep ocean paleoenvironments. Here, we present new evidence from seismic reflection and borehole data for two major contourite systems that document sustained bottom currents on the northern Vøring Plateau during the Early Eocene and along the western Barents Sea margin in the Oligocene. Our findings imply the presence of deep-water circulation in the Norwegian-Greenland Sea 15 Myr earlier than previously documented, before the opening of the Fram Strait and likely sustained inflow across the Greenland-Scotland Ridge. By compiling the main contourite occurrences and matching them to the tectonic events, seaways, and paleoclimate records within the Norwegian-Greenland Sea we revise its evolution and impact on the current climate, highlighting the temporal correlations between tectonic reorganizations, magmatism, onset of ocean circulation, and glaciations. Our findings suggest that periodic ocean circulation changes during the early Cenozoic were possibly governed by variations in mantle plume activity and magmatism, laying the basis for the Atlantic Meridional Overturning Circulation (AMOC) and thereby influencing climate in NW Europe.