Linking physical property records of quaternary sediments to Heinrich events

Ice rafted debris in high latitude ocean sediments represent a complex record of the changing paleoenvironment of the oceans and, in particular, of the growth and decay of ice sheets along the margins of high latitudes. Physical properties measured on sediment cores taken from the Rockall Plateau were examined to determine the distribution of ice rafted debris layers and Heinrich events in the northeastern North Atlantic. These sediment core records may provide one of the keys to reconstruct the iceberg flow between the northeastern Atlantic and the Norwegian Sea. Magnetic susceptibility (MS) and Gamma Ray Attenuation Porosity Evaluator (GRAPE) density changes of these cores revealed that since about 65 ka, dropstone layers are recorded in both MS and GRAPE data of Rockall Plateau sediments. Rockall Plateau sediments show peaks in physical properties that correlate with Heinrich events (H-1, H-2, H-4, H-5, H-6). Heinrich layer 3 was not observed. The stratigraphy and physical properties represent the Heinrich layers: H-1 = 14-15 ka (MS = 52 mu cgs, rho = 1.64 g/cm(3)), H-2 = 23 ka (MS = 64 mu gs, rho = 1.8 g/cm(3)), H-4 = 41 ka (MS = 53 mu cgs, rho = 1.75 g/cm(3)), H-5 = 50 ka (MS = 53 mu cgs, rho = 1.75 g/cm(3)), H-6 = 64 ka (MS = 100 mu cgs, rho = 1.69 g/cm(3)). Heinrich events at Rockall Plateau sites point to a northward flow of icebergs in the northeastern Atlantic which may indicate a flow pattern to regions north of 54 degrees N.