North-eastern Laurentide, western Greenland and southern Innuitian ice stream dynamics during the last glacial cycle



Precise relationships between high-frequency ice sheet dynamics and late Quaternary climate variability are still poorly understood, notably with regard to their relative timing and causal mechanisms. Baffin Bay is of particular interest in this regard due to the influence of ice streaming activities from the north-eastern Laurentide, southern Innuitian and western Greenland ice margins on its sedimentary regimes during glacial times. Here we document such ice margin dynamics using a sedimentological analysis performed on a piston core from central Baffin Bay and spanning the last 115 ka. Lithofacies analysis and mineralogical assemblages are used to reconstruct sediment sources (using the SedUnMix program) and depositional mechanisms. Coarse detrital carbonate (DC, dolomite-rich) layers are attributed either to north-eastern Laurentide and Innuitian ice stream surges or to pervasive ice rafted debris delivery processes at distinct periods. Out-of-phase fine-grained glaciomarine sediments with a mineralogical signature from western Greenland, linked to Uummannaq ice streaming activity, are interbedded with the coarse DC layers. The new results suggest that during the last glacial cycle, the north-eastern Laurentide and southern Innuitian ice streams were sensitive to high-frequency climate fluctuations, such as the Dansgaard–Oeschger events, while the western Greenland margins were more sensitive to large-scale climatic/oceanic reorganizations, such as relative sea-level changes and/or advection of warmer Atlantic waters into the bay.