CAN THE ICE-SHEET CHRONOLOGY IN WESTERN NEW YORK BE IMPROVED WITH INFRARED STIMULATED LUMINESCENCE DATING?

Western New York hosts a detailed geomorphic record of ice-margin positions spanning the last deglaciation. Landforms along a condensed flowline between Lake Ontario and the Pennsylvania state line span from the LGM to ~13 ka, although the existing chronology is largely via correlation with landforms dated elsewhere (e.g., Ohio, eastern New York). Within this timeframe are moraines that mark dozens of ice-margin positions, many of which have associated outwash plains and deltas. Organic remains associated with landforms are sparse, moraine instability has been shown to limit the usefulness of basal radiocarbon ages from kettles, and quartz-bearing erratic boulders are absent for cosmogenic-nuclide dating. As a first test to assess the potential for infrared stimulated luminescence (IRSL) dating to systematically date the ice-margin sequence preserved in western New York, we obtained nine IRSL ages from deposits (glaciofluvial, deltaic, loess) of four different ages. From these ages we conclude the following: (1) Despite local bedrock geology consisting of quartz- and feldspar-poor lithologies, sufficient grains are present for IRSL dating of K-feldspar single grains. (2) Single-grain populations are positively skewed (as expected in poorly bleached glacial depositional settings), but minimum age models produce meaningful ages. (3) The ages are broadly consistent with the inferred glacial history, but with only 1-2 samples per site, scatter is currently too high to add much new precision to ice sheet history. Future dating of multiple samples per site across a range of features (outwash, deltas, kames) could improve precision.