Late Quaternary iceberg-rafted detritus events on the Denmark Strait–Southeast Greenland continental slope (∼65°N): related to North Atlantic Heinrich events?

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HU93030-007 LCF (65°01.39′N and 30°14.81′W) is a 4.5 m long, giant (11 cm diameter) piston core from 1800 m water depth on the continental slope, south of the Denmark Strait sill. The core sampled acoustically stratified sediments at a site below the Kangerlussuaq Trough. Nine AMS 14C dates on planktic foraminifera indicate that the core spans ∼14 to 28 14C ka. The sediments consists of two principal lithofacies: Lithofacies I (LI) comprises tan/ochre intervals with abundant ice-rafted sandstone/siltstone clasts larger than 2 mm and with an average thickness of 47 cm; it is also associated with peaks in carbonate content and TOC%. Lithofacies II (LII) consists of fine-grained, dark gray, hemipelagic sediment. There are three distinct intervals of LI dated between 14.3 and 15.5 (LIc), 20.1 and 21.9 (LIb), 24.7 and 25.8 (LIa) ka. The ages suggest that deposition of LI is approximately coeval with Heinrich events 1 and 2 in the North Atlantic, whereas LIa appears younger than H-3. Lithofacies I is derived from far-travelled ice bergs from an unknown source, but not from the northeastern Laurentide Ice Sheet. Stable isotope studies on Neogloboquadrina pachyderma sinistral show little evidence for significant meltwater events associated with LI, but surprisingly, light oxygen isotopic events are present in the benthic foraminiferal analyses ( Cibicidoides wuellerstorfi and Melonis zaandamae). The ages of the HU93030-007 iceberg-rafted detritus (IRD) events are similar to IRD peaks in cores north of Denmark Strait, on the East Greenland slope. HU87033-009 LCF (SE Baffin slope, 62°30.99′N and 59°26.82′W, 1437 m wd) is situated in a similar position to HU93030-007 but with respect to the Laurentide Ice Sheet; its δ 18O record on planktic foraminifera is virtually identical to that of HU93030-007. The timing of IRD events is similar in both these cores between 14 and 30 ka. H-3 may be present in HU87033-009 as an IRD event, but in contrast to H-1 and H-2, it is not evident as a discernible detrital carbonate event.