123-1 Paleoenvironmental investigation of Jackson Lake (Grand Teton National Park, USA) leveraging high resolution CHIRP seismic reflection data and radiocarbon-dated sediment cores

Session: Quaternary Research to Characterize Environmental and Geological Hazards

Presenting Author:

John Dilworth

Authors:

Dilworth, John¹, Johnson, Sarah E², McGlue, Michael M.³, Whitehead, Sam⁴, Thigpen, Ryan⁵, Cortese, Callia⁶, Brown, Summer⁷, Woolery, Edward W.⁸, Yeager, Kevin M.⁹, Matocha, Christopher J.¹⁰

(1) Earth and Environmental Sciences, University of Kentucky, Toledo, OH, USA, (2) Earth and Environmental Sciences, University of Kentucky, Lexington, Kentucky, USA, (3) University of Kentucky Earth and Environmental Sciences, Lexington, KY, USA; Kentucky Geological Survey, Kentucky Geological Survey (State Geologist and Director), Lexington, Kentucky, USA, (4) Dept. of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA, (5) Earth and Environmental Sciences, University of Kentucky, Lexington, KY, USA, (6) Earth and Environmental Sciences, University of Kentucky, Lexington, Kentucky, USA, (7) Earth and Environmental Sciences, University of Kentucky, University of Kentucky, Kentucky, USA, (8) Earth and Environmental Sciences, University of Kentucky, Lexington, Kentucky, USA, (9) Dept. of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA, (10) Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA,

Abstract:

Seismic and sedimentary records from Jackson Lake (Grand Teton National Park, Wyoming, USA) provided new insights into the Late Quaternary tectonic and hydroclimatic history of a region known to have considerable earthquake hazard potential. Here, we present a new paleoenvironmental reconstruction for Jackson Lake using high-resolution compressed high-intensity radar pulse (CHIRP) seismic reflection data and sediment cores from Moran Bay, located adjacent to the active Teton fault. Three seismic units (SU) are present and interpreted as: SU-1, the acoustic basement; SU-2, prograding clinoforms in a fluvio-deltaic and shallow lacustrine environment; and SU-3, a shallow water environment. To support seismic interpretations a radiocarbon-dated sediment core (13.8 m - refusal) was collected. Radiocarbon ages indicate that the core spans ~10.4 cal ka BP to present. The stacking patterns of deltaic clinoforms are best explained by increased accommodation in Moran Bay around 10 ka, consistent with a major earthquake and subsidence along the Teton fault. Two turbidites identified in the strata are temporally aligned (10.3 ± 0.4, and 8.3 ± 0.3 cal ka BP) with earthquakes on the Teton fault that have been previously identified in terrestrial and lacustrine paleoseismic records. From ~10.4–6.6 cal ka BP core sediments were relatively rich in clay with highly variable magnetic susceptibility and organic carbon concentrations. Deposition was likely influenced by evolving stream networks and a relatively dry paleoclimate during this period. From ~6.6–2.7 cal ka BP core sediments have higher sand and organic carbon concentrations, suggesting variable fluvial discharge and climate instability. The youngest core records produced an increase in sedimentation rate, sand and organic carbon concentrations, coinciding with greater effective moisture, higher lake levels, and increased watershed vegetation density. Based on clinoform rollover position, water levels at ~2,042 (pre ~ 10.4 cal ka BP), ~2,049 and 2053 m asl (10.4 cal ka BP – 1908 CE) characterized Moran Bay during the Holocene. Together, the seismic and core data records indicate a complex and dynamic Holocene lake evolution controlled by fault motion and water level changes.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10093

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