Magnetic Fingerprints of Greenlandic and Icelandic Sediment Sources to the Eirik Drift through Five Glacial Terminations and Interglaciations

Analysis of the marine geological record provides a potential way to ground truth ice-sheet models aimed at constraining the size of the Greenland Ice Sheet (GIS). Sediment contributions to the Eirik Drift from Greenland and Iceland are modulated by the interplay of GIS meltwater runoff and the strength of ocean currents. Here we use grain-size specific magnetic properties to discriminate between Icelandic and Greenlandic sources of sediment to the Eirik Drift over the last 420 kyr. Sediment core MD99-2227 (58.12°N, 48.22°W, 3460m water depth) shows strong bulk magnetic susceptibility responses during glacial terminations and interglaciations, opposing the expected North Atlantic trend. Magnetic properties of both the source areas and the core's sediments possess strong particle size dependence with the silt fraction carrying much of the magnetic signal. All Icelandic fractions are dominated by fine pseudo-single domain (PSD) size magnetic grains. In contrast, Greenlandic samples possess greater variation in magnetic grain size with only fine silt and clay fractions possessing Icelandic-like PSD grains; Greenlandic silts and sands are dominated by coarser PSD and multi-domain grains. Differences in magnetic grain size of the clay and silt fractions of MD99-2227 during glacial terminations links the high silt fluxes to Greenlandic sources which reflects enhanced GIS ablation. Greenlandic sources are highest during TII (Marine Isotope Stages, MIS, 6-5e) and TV (MIS 12-11) which agree with sea-level data that suggest global ice volume minima during these periods. At the peak of MIS 11, Greenlandic signatures decrease 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.