Fingerprints of Greenlandic and Icelandic Sediment Sources to the North Atlantic through Five Glacial Terminations and Interglacials

Ice sheet models vary substantially in their predictions of the size of the Greenland Ice Sheet (GIS) during previous interglacials. This uncertainty makes it difficult to constrain the sensitivity of the GIS to projected climate warming and asses the role of the GIS in future sea level rise. The geological record provides an alternative method to ground truth the relative extent of the GIS during previous interglacials. Ocean cores from the Eirik Drift contain a record of exported terrestrial sediments with variations in their properties linked to the size and nature of the GIS. The silt fraction (3-63 μm) is a significant product of glacial erosion, has limited distal transport potential and forms a major component of Erik Drift sediments. Therefore properties of the silt fraction are most useful to estimate relative fluxes from different source areas and potentially relate the source of erosion to the size of the GIS. Here we construct and compare particle-sized magnetic 'fingerprints' of Greenlandic and Icelandic terrestrial sources to the particle sized magnetic record of MD99-2227 and HU90-013-013 through glacial terminations I - V and subsequent interglacials, spanning 420kyrs. The magnetic properties of both the source areas and the core sediments possess strong particle size dependence with the silt fraction carrying much of the magnetic signal. Magnetic hysteresis measurements show the five terminations to be relatively similar and homogeneous compared to other time periods; possibly reflecting a strong Greenlandic terrestrial source. Although Icelandic (basaltic) sediment sources dominate the record (similar to the findings of Colville et al., 2011), Precambrian Greenlandic contributions increase during terminations, which are linked to ablation of the GIS. Greenlandic sources are highest during TII (Marine Isotope Stages, MIS, 6-5e) and TV (MIS 12-11) concurrent with benthic δ18O data (e.g. Lisiecki and Raymo, 2005) suggesting minimum global ice volume during these periods. At the peak of MIS 11, Greenlandic signatures decrease to be replaced by Icelandic contributions reflecting either greater distal transport of sediment or reduced connectivity to the core site resulting from greatest retreat of the GIS in the last 420 kyrs.