Paleoglaciological insights from the age and morphology of the Jesse moraine belt, western Canadian Arctic

The Jesse moraine belt (350 km-long) was deposited by the northwest Laurentide Ice Sheet on Banks and Victoria islands in the western Canadian Arctic Archipelago during the last deglaciation. The moraine belt is composed of (ice-cored) controlled moraines that contrast markedly with adjacent glacial sediments deposited during preceding ice sheet retreat. More than 80 radiocarbon ages from fossil molluscs illustrate that deposition of the moraine belt was brief, occurring between 13.75 and 12.75 cal ka BP. The chronology demonstrates that moraine deposition was coeval with ice sheet drawdown and ice streaming on adjacent Victoria Island. Detailed geomorphic mapping demonstrates that the moraine belt is the product of a regional change in ice-marginal processes. This involved a predominantly cold-based ice margin giving way to polythermal bed conditions, which were conducive to widespread deposition of controlled moraines and ice stream bedforms. The expansion of warm-based thermal regimes in the northwest Laurentide Ice Sheet followed widespread ice sheet withdrawal from M'Clure Strait and western Amundsen Gulf. This suggests a re-equilibration of regional ice divides in response to rapidly changing ice sheet margins and surface gradients. The reconstructed dynamical behavior of the northwest Laurentide Ice Sheet provides new insights regarding ice sheet responses to late-glacial climate and relative sea level change, among other variables.

► Fieldwork documents the former dynamics of the NW Laurentide Ice Sheet.
► >80 radiocarbon ages constrain ice dynamics between 14 and 12.75 ka BP.
► Onset of polythermal ice margins is recorded by widespread controlled moraines.
► Controlled moraine deposition followed rapid ice retreat from marine channels.
► Rapid oscillations of marine-based glaciers pervade the geological record.