An additional Heinrich ice-rafting event is identified between Heinrich events 5 and 6 in eight cores from the Labrador Sea and the northwest Atlantic Ocean. It is characterized by sediment rich in detrital carbonate (40% CaCO3) with high concentration of floating dropstones, high coarse-fraction (% > 150 µm) content, and has a sharp contact with the underlying but grades into the overlying hemipelagic sediment. It also shows lighter d18ONpl values, indicating freshening due to iceberg rafting and/or meltwater discharge. This event is correlated with Dansgaard-Oeschger event 14 and interpreted as an additional Heinrich event, H5a. The thickness of H5a in the Labrador Sea reaches up to 220 cm. This additional Heinrich event has also been reported in cores PS2644 and SO82-5 from the northern North Atlantic. With the recognition of H5a the temporal spacing between Heinrich events 1 to 6 becomes more uniform (~7 ka).

Radiocarbon convention age, -450 years for surface ocean reservoir age, is corrected according to Bard (1988) back to 20 ka (Bard et al., 1993) and back to 50 ka according to the scheme of Laj et al. (2000). Ages marked with * appear too young to be considered real and were discarded. Radiocarbon dates younger than 24 ka are converted to calendar age according to the CALIB4.3 program (Stuiver et al., 1998) and ages between 24 and 40 ka BP are calibrated according to the scheme of Beck et al. (2001), respectively.

Supplement to: Rashid, Harunur; Hesse, Reinhard; Piper, David J W (2003): Evidence for an additional Heinrich event between H5 and H6 in the Labrador Sea. Paleoceanography, 18(4), 1077