PP046-0014
Reduced evaporation rates primarily led to growth of glacial Lake Bonneville

Wednesday, 16 December 2020
Poster
Alexandrea Jay Arnold1, John Arthur Mering2,3, Lilian Chou4, Audrey Brown4, Victoria A Petryshyn1,5, Juan Manuel Lora1,6, Daniel Enrique Ibarra7, Charles G Oviatt8 and Aradhna E. Tripati2, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)University of California, Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (3)University of Waikato, Hamilton, New Zealand, (4)University of California Los Angeles, Los Angeles, United States, (5)University of Southern California, Environmental Studies Program, Los Angeles, CA, United States, (6)Yale University, Department of Earth and Planetary Sciences, New Haven, CT, United States, (7)University of California Berkeley, Berkeley, CA, United States, (8)Kansas State Univ, Manhattan, KS, United States
Abstract:
During the latest Pleistocene, Lake Bonneville was the largest pluvial lake within the Great Basin. After the Last Glacial Maximum (21 ka), the lake transgressed to reach a maximum surface area of roughly 50,000 km2, and exists in smaller remnants today as the modern Great Salt Lake. The hydrologic factors associated with Lake Bonneville’s transgression and subsequent disappearance are not fully understood. Given the size of Lake Bonneville at its maximum extent, previous work has hypothesized that the lake system was self-sustaining at this time, however, a surplus in the basin’s moisture budget is required to increase lake levels in an inward-draining basin. In addition, most proxy systems used to quantify change in hydroclimate can only provide estimates of effective moisture and cannot resolve precipitation separately from evaporation.


Here, we use carbonate clumped isotope thermometry and mass balance modeling to define paleohydrologic parameters including temperature, evaporation, precipitation, and water δ18O. We show that localized lake-effect precipitation allowed Lake Bonneville to be self-sustaining, but attribute growth of the lake system to decreased evaporation rates. These novel results not only help to reshape our understanding of the conditions associated with major hydroclimate shifts in the Southwest, but also represent a new methodology that can be applied to other basins and regions.

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