35-3 Landscape Legacy –– Cosmogenic Isotopic Insight into the Erosion and Sediment Transport Efficacy of the Laurentide Ice Sheet in East Central North America

Session: Ice sheets, glaciers, and landscapes, oh my! (Posters)

Poster Booth No.: 36

Presenting Author:

Isabelle Larson

Authors:

Larson, Isabelle ¹, Bierman, Paul², Schmidt, Amanda ³, Corbett, Lee⁴, Hulbert, Josh⁵, Faust, Kira⁶, Thompson, Beck ⁷, Caffee, Marc⁸, Valachovics, Thomas⁹, Esch, John¹⁰, Bridges, Aether¹¹, Cohen, Julia¹², Erber, Nathan¹³

(1) Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, , (2) Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, , (3) Geosciences, Oberlin College, Oberlin, , (4) Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, , (5) Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, , (6) Geosceinces, Oberlin College, Oberlin, , (7) Geosciences, Oberlin College, Oberlin, , (8) Physics, Purdue University, West Lafayette, , (9) Michigan Geological Survey, Western Michigan University, Kalamazoo, , (10) Michigan Geological Survey, Western Michigan University, Kalamazoo, , (11) Geosciences, Oberlin College, Oberlin, , (12) Geosciences, Oberlin College, Oberlin, , (13) Western Michigan University, Kalamzoo, ,

Abstract:

During the last several million years, ice sheets intermittently covered much of the Northern Hemisphere; yet the degree to which they erode bedrock and transport sediment remains poorly constrained. Here, we determine the erosivity and sediment transport efficacy of repeated Laurentide Ice Sheet glaciations in Michigan using in-situ produced cosmogenic nuclides. We measured concentrations of ¹⁰Be (with ²⁶Al analyses forthcoming) in quartz isolated from 17 samples of glacially deposited sediment recovered from two deep sediment cores (C1: 76 m; C2: 134 m) collected along the eastern shore of Lake Michigan in Muskegon County. Core stratigraphy records alternating glacial lacustrine sediments and subglacial tills, providing a framework to evaluate ice sheet behavior through time. Sediment in these cores includes glacial and post glacial deposits associated with the Lake Michigan Lobe. The oldest glacial sediments above Paleozoic bedrock likely predate the LGM and are capped by glaciolacustrine sediments associated with Glacial Lake Milwaukee. Younger till, overlain by lacustrine sediment,is  found closer to the surface. We purified quartz and extracted nuclides at the University of Vermont; isotope ratios were measured at PRIME Laboratory, Purdue University. Using depth-production rates and estimated deglacial ages, we applied minimal corrections for late-glacial and Holocene exposure at depth. Upper core sections composed of interbedded sand, silt, clay, and diamict exhibit similar average ¹⁰Be concentrations (C1: 1.29 × 10⁴ atoms g⁻¹, n=4; C2: 1.34 × 10⁴ atoms g⁻¹, n=6). Lower core sections display variable average ¹⁰Be concentrations (C1: 1.14 × 10⁴ atoms g⁻¹, n=3; C2: 3.90 × 10⁴ atoms g⁻¹, n=5). Sandstone at the base of each core shows markedly different ¹⁰Be concentrations (C1: 6.0±4.0 × 10² atoms g⁻¹, C2: 3.42±0.19 × 10⁴ atoms g⁻¹). The presence of non-zero ¹⁰Be concentrations mandates inheritance from prior periods of near-surface exposure, suggesting limited subglacial erosion and inefficient glacial sediment transport. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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