ICEBERG PRODUCTION, DEBRIS RAFTING, AND THE EXTENT AND THICKNESS OF HEINRICH LAYERS (H-1, H-2) IN NORTH-ATLANTIC SEDIMENTS

The pattern of Heinrich-layer distribution for the last two events (H- 1, similar to 14.5 and H-2, similar to 21.1 ka), mapped from magnetic susceptibility analysis of more than 50 North Atlantic Ocean cores, pr ovides the most detailed information to date on their extent and thick ness, An integrated spatial average thickness for the layers is 10-15 cm, and there is a strong distance decay eastward, The pattern of depo sition over the North Atlantic is similar for events H-1 and H-2, indi cating that icebergs followed similar drift tracks. Rates of iceberg p roduction and sediment flux from the Hudson Strait drainage basin of t he North American Laurentide ice sheet, the major iceberg source for t he events, were calculated by using a mass-balance approach, This prov ides an envelope of sedimentation rates and the prediction that it wou ld take between 50 and similar to 1250 yr of iceberg sediment delivery to accumulate a Heinrich layer averaging 10 cm thick over the North A tlantic, depending on the model assumptions used, The most likely dura tion of Heinrich events is 250-1250 yr.