The Role of Hudson Strait Outlet in Younger Dryas Sedimentation in the Labrador Sea

Abstract

Abrupt Climate C Geophysical Mon Copyright 2011 b 10.1029/2010GM In the Younger Dryas (YD) the circum-North Atlantic region returned to near glacial conditions, widely attributed to the release of fresh water from the Laurentide Ice Sheet (LIS). Hudson Strait was a major outlet for fresh water, icebergs, and sediment from the LIS that deposited Heinrich (H) layers throughout the North Atlantic. Heinrich layer 0 (H0), the YD equivalent ice-rafting event, has been reported to be absent in deep water seaward of the mouth of Hudson Strait. We have identified meter-thick H0 carbonate-rich sediments of YD age seaward of Hudson Strait as nepheloid-flow deposits and as turbidites on the northeast Sohm Abyssal Plain. Otherwise, H0 is generally absent in cores from the Labrador Basin. The thick proximal H0 bed indicates an important supply of fresh water through the Hudson Strait outlet of the LIS during the YD. The sparse distal sediment distribution and values in the planktonic foraminiferal δO in the Labrador Sea, less depleted than during H1, were probably the result of the position of the ice margin, duration of freshwater discharge, and dilution of freshwater signature with the ambient seawater during H0. This change is interpreted to result from differences in the retreat of the ice margin at the mouth of Hudson Strait, resulting in different styles of sediment and freshwater transport during the H0 compared to earlier H events.