University of Delaware, United States

Baffin Bay was an extremely "glacial" ocean, surrounded by several ice sheets. The Quaternary sediments of Baffin Bay include detrital carbonate-rich (DC-) facies that represent the input of glacially-derived sediment from Paleozoic Basins. In the Labrador Sea, east of Hudson Strait, DC-events are coeval with Heinrich events (H-). The Baffin Bay DC- events are dolomitic in composition, whereas those from Hudson Strait are principally calcitic. We obtained 20 14C dates, mainly on planktic foraminifera , from 9 cores that form a N-S transect. We bracketed the basal age of the uppermost DC event and the top of a thick DC-event that occurs approximately 4 m core depth in several cores. Several other DC-events occur between these two dated intervals. Dates from ca. 1 m indicate an age for the uppermost DC-event < or =12.4 ka; whereas the age of the event at ca. 4 m core depth is > or =45 ka. For most of the records the average rate of sediment accumulation is 1+ or - m/10 ky--close to that estimated previously from ODP Leg 105, Site 645 in Baffin Bay. However, sedimentation rates increase markedly immediately north of the 600 m deep Davis Strait sill to approximately 10 m/10 ky. There are between 5 and 6 DC-events between our two bracketed events indicating a average periodicity of approximately 6 ky/cycle. At ODP 645 it had been previously speculated, after interpolation from the Brunhes/Matuyama paleomagnetic boundary, that the DC-events at that site had an average periodicity of ca. 7 ky!