A NOVEL HIGH-RESOLUTION HOLOCENE RECORD OF ENVIRONMENTAL CHANGE FROM GRAND TETON NATIONAL PARK, WYOMING

Water resources in the American West are vital to the nation's economy and sustain millions of livelihoods, particularly in semi-arid mountainous states such as Wyoming and Idaho. However, climate change poses an increasing threat to water availability in these areas. Pairing climate models with high-resolution sedimentary records offers critical insights into hydroclimate dynamics, yet geological archives of environmental change in the region remain limited.

This study analyzes a newly available Holocene sedimentary archive—a 30-meter-long sediment core extracted from Jackson Lake in Grand Teton National Park, Wyoming. This core provides a unique opportunity to develop high-resolution geochemical proxies for reconstructing hydroclimate variability across the Holocene. Jackson Lake's water balance is dominated by the Snake River, which enters the lake from the north and exits through the Jackson Lake dam on the southeastern shoreline. The Snake River is the largest tributary of the Columbia River and is critical to valuable downstream agricultural and ranching activities. Understanding the Snake River system's response to climatic shifts over the Holocene will yield valuable insights for water resource management and conservation. An age-depth model produced using radiocarbon and tephra layers indicates that the core spans the entirety of the Holocene (~12,000 years-present). We seek to test the hypothesis that Snake River discharge controls Jackson Lake levels in the Late Quaternary, and we predict changes in deepwater lithofacies and geochemistry will follow water levels. Preliminary observations of the core show packages of laminated muds punctuated by thick beds of structureless or internally deformed muds and sands. Laminated muds vary along the length of the core with respect to color and chemical composition, hinting at evolving limnological conditions over the Holocene. Deformed muds correlate with seismic evidence of slope failure and mass transport, potentially driven by earthquakes. Further findings will be presented based upon ongoing analysis of XRF data, physical properties, and lithofacies characteristics.