WORKING TOWARD A NEW GENERATION OF NORTH AMERICAN DEGLACIATION MAPS

The North American Ice Sheet Complex (NAISC) consisted of the Laurentide, Cordilleran and Innuitian ice sheets that coalesced at the Last Glacial Maximum (LGM) during Oxygen Isotope Stage 2. As the largest ice mass of the Northern Hemisphere, the NAISC played a critical role in the evolution of the Quaternary climate, Earth rheology and sea level. Currently, our knowledge of the deglaciation of the NAISC is based largely on radiocarbon-based reconstructions of the former ice margin (notably, Dyke et al., 2003 and Dalton et al. 2020), which may lack precision because of the limiting nature of radiocarbon ages. Our project will produce a new generation of deglaciation maps independent of all previous efforts and utilizing both radiocarbon and non-radiocarbon data (e.g. cosmogenic ages, optically stimulated luminescence ages) to obtain a more precise estimate of ice margin positions through the deglaciation. We will detail our progress on this multi-year project, including the integration of all available geochronological data types, our methods for ranking each data type, min/max criteria for each isochrone and mapping of geomorphic features. We will also show preliminary maps that compare our new interpretations to the previous radiocarbon work. When complete, this new generation of deglaciation maps will put the NAISC on par with recent progress on the Eurasian Ice Sheet (integration of all geochronological data types and development of min/max/best isochrones; Hughes et al., 2016). Furthermore, the new deglaciation chronology will be of use for refining new iterations of numerical ice sheet models and thus improving our understanding of the last glaciation of the Northern Hemisphere.