Sedimentation on the Feni Drift and late Glacial bottom water production in the northern Rockall Trough

Abstract

Between the Last Glacial Maximum (18 ka) and the present day, a variety of contrasting oceanographic conditions, including changes in surface and bottom water circulation patterns have existed in the North Atlantic. Evidence for the presence of bottom currents in winnowed silt horizons in the Feni Drift suggests that deep water may have been produced in this region during glacial—deglacial intervals. Current activity, and thus perhaps deep water production, was apparently intermittent, and may have been controlled by a process analogous to the formation of Labrador Sea Water. This involves cooling and deep ocean convection during winter months. Physical factors controlling this production would be temperature and salinity of upper waters which would govern the density, and wind stress necessary for vertical overturn coupled with absence of ice cover. Evidence of bottom current activity suggests that deep water production occurred in the Rockall Trough throughout Termination 1A which closely corresponds to Fairbanks (1989) meltwater pulse 1a (mwp 1a). Production of deep water in this region apparently ceased shortly after the decline in influence of the meltwater influx.