Dynamics of North Atlantic deep water masses during the Holocene

High resolution flow speed reconstructions of two core sites located on Gardar Drift in the North East Atlantic Basin and Orphan Knoll in the North West Atlantic Basin reveal a long-term decrease in flow speed of North East Atlantic Deep Water (NEADW) after 6,500 years. Benthic foraminiferal oxygen isotopes of sites currently bathed in NEADW show a 0.2‰ depletion after 6,500 years, shortly after the start of the development of a carbon isotope gradient between NEADW and Norwegian Sea Deep Water. We consider these changes in near-bottom flow vigour and benthic foraminiferal isotopic records to mark a significant reorganization of the Holocene deep ocean circulation, and attribute the changes to a weakening of NEADW flow during the mid to late Holocene that allowed the shoaling of Lower Deep Water and deeper eastward advection of Labrador Sea Water into the North East Atlantic Basin