Deglaciation of the north American ice sheet complex in calendar years based on a comprehensive database of chronological data: NADI-1

• Published in: Quaternary Science Reviews
• Main Authors: Dalton, April S., Dulfer, Helen E., Margold, Martin, Heyman, Jakob, Clague, John J., Froese, Duane G., Gauthier, Michelle S., Hughes, Anna L.C., Jennings, Carrie E., Norris, Sophie L., Stoker, Benjamin J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: ResearchInstitutes_Networks_Beacons/MERI; name=Manchester Environmental Research Institute; Ice Sheet
• Online Access: https://research.manchester.ac.uk/en/publications/beb41c67-545f-4a41-9a15-258623b0de8e; https://doi.org/10.1016/j.quascirev.2023.108345; http://www.scopus.com/inward/record.url?scp=85176235571&partnerID=8YFLogxK; https://www.mendeley.com/catalogue/74d9f64b-7d02-3091-ba6e-d1c0b8e76c01/

The most recent deglaciation of the North American Ice Sheet Complex (NAISC: comprising the Innuitian, Cordilleran, and Laurentide ice sheets) offers a broad perspective from which to analyze the timing and rate of ice retreat, deglacial sea-level rise, and abrupt climate change events. Previous efforts to portray the retreat of the NAISC have been focused largely on minimum-limiting radiocarbon ages and ice margin location(s) tied to deglacial landforms that were not, for the most part, chronologically constrained. Here, we present the first version of North American Deglaciation Isochrones (NADI-1) spanning 25 to 1 ka in calendar years before present. Key new features of this work are (i) the incorporation of cosmogenic nuclide data, which offer a direct constraint on the timing of ice recession; (ii) presentation of all data and time-steps in calendar years; (iii) optimal, minimum, and maximum ice extents for each time-step that are designed to capture uncertainties in the ice margin position, and; (iv) extensive documentation and justification for the placement of each ice margin. Our data compilation includes 2229 measurements of 10 Be, 459 measurements of 26 Al and 35 measurements of 36 Cl from a variety of settings, including boulders, bedrock surfaces, cobbles, pebbles, and sediments. We also updated a previous radiocarbon dataset (n = 4947), assembled luminescence ages (n = 397) and gathered uranium-series data (n = 2). After scrutiny of the geochronological dataset, we consider >90% of data to be reliable or likely reliable. Key findings include (i) a highly asynchronous maximum glacial extent in North America, occurring as early as 27 ka to as late as 17 ka, within and between ice sheets. In most marine realms, extension of the ice margin to the continental shelf break at 25 ka is somewhat speculative because it is based on undated and spatially scattered ice stream and geomorphic evidence; (ii) detachment of the Laurentide and Cordilleran ice sheets took place gradually via southerly and northerly ...