Dansgaard-Oeschger events: is there a signal off the Hudson Strait Ice Stream?

It is generally accepted that the dramatic Heinrich (H-) events were principally sourced from the major Hudson Strait drainage basin of the Laurentide Ice Sheet, but it is not known whether the higher frequency Dansgaard-Oeschger (D-O) events have an imprint on sediments deposited during the inter-H intervals in ice-proximal slope sediments. This paper examines this question by an analysis of data from cores on the SE Baffin slope. Because the proxies for Heinrich events are so massive in scale, we removed the major H- events (H-1, H-2 and H-4) from the records so as to better examine the structure of data in the intervening hemipelagic sediments. The period of interest extends between similar to 15 and 40 cal ka (interstadial events 2-8); resolution varies with the proxy to between 210 and 700 yrs per sample. In HU87033-009 from the lower slope, a total of twelve variables (for example, delta(18)O, mass magnetic susceptibility, calcite/dolomite ratio, number of IRD > 2 mm), show a variety of multi-millennial oscillations, although not all of the same amplitude nor frequency; several parameters show little correlation with the GISP2 delta(18)O record. However, a comparison of CIE* sediment color (L) from HU87033-009 and HU97048-007 (from the upper slope) with the GISP2 oxygen isotope record, suggests that a substantial correlation exists between the records. Such changes might be associated with either detrital carbonate content or foraminiferal concentrations. Analysis suggests, however, that the first possibility is correct, hence suggestive of a glaciological response of the Hudson Strait Ice Stream with D-O events. In the NW Labrador Sea, the sediment records from around H-3 time (similar to 30 cal ka) show excursions which might be correlative within this event, but its amplitude is not unusual compared to events both before and after. This reaffirms the argument that H-3 represents a different glaciological response. A significant issue discussed in this paper is the inherent ambiguity of correlating records whose errors in the time domain approach that of a dominating periodicity, in this case ca. 1.5 kyr. (C) 2001 Published by Elsevier Science Ltd.