Phase relationships of North Atlantic ice-rafted debris and surface-deep climate proxies during the last glacial period

We report stable isotope, core scanning XRF, and ice-rafted detritus (IRD) data in glacial-aged sediments from piston Core KN166-14-JPC-13 (hereafter referred to as JPC-13) retrieved at 53.1°N 33.5°W on the southern Gardar Drift, North Atlantic. A chronology was established by correlating millennial-scale features in the benthic δ18O record to Portuguese Margin Core MD95-2042. Once the alignment of benthic δ18O of JPC-13 to MD95-2042 is fixed, the relative timing of proxy variables is used to determine the phasing of changes in IRD and surface-deep hydrography. Each peak in North Atlantic IRD coincided with a decrease in benthic δ18O that, in turn, has been linked to warming in Antarctica (Events A1–A7). The IRD pulses are followed shortly thereafter by abrupt decreases in planktonic δ18O, indicating warming and increased heat transport to the subpolar North Atlantic associated with Greenland interstadials (GIS) 8, 12,14, and 16–17. Grain-size and elemental (K/Ti) variations indicate that Iceland–Scotland Overflow Water (ISOW) was stronger during these long, warm interstadial periods of Marine Isotope Stage (MIS) 3. The results are consistent with interhemispheric phase relationships inferred from Iberian Margin sediment cores and with methane synchronization of Greenland and Antarctic ice cores.