T47 The Last Glacial–Interglacial Transition in Western North America: Paleoclimate Proxies, Environmental Responses, and Data-Model Comparisons

Sunday, 9 October 2022
1:30 PM - 5:30 PM
503

MODELLING CLIMATE CONSTRAINTS ON THE FORMATION OF PLUVIAL LAKE BONNEVILLE IN THE GREAT BASIN, UNITED STATES

Paper number: T47-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

Lake Bonneville was the forefather of the modern Great Salt Lake, expanding its footprint to cover roughly 50,000 km2, nearly 1/4 the size of Utah. Its immense size has long raised the question of what climatic conditions were required sustain such a large lake, and whether its high stand shorelines record a fundamentally wetter climate than today. This study addresses this question using a hydrologic balance model to estimate the range of precipitation and temperature (P‐T) conditions required to maintain Lake Bonneville at two lake levels during the late Pleistocene. By intersecting lake-derived P-T curves with P-T curves determined from glacial modelling in the Wasatch Mountains we are able to place tighter climatic constraints, which suggest gradually increasing wetness from ~21 to 15 ka. We propose that Lake Bonneville approached its highest level from ~21–20 ka under conditions roughly 9.5°C colder but only 7% wetter than modern. As the lake neared its pre-flood Bonneville level (~18.2–17.5 ka), we estimate that climate conditions were roughly 16% wetter and ~9°C colder than modern. Lake Bonneville ultimately abandoned the overflowing Provo level at ca. 15–14.8 ka, under conditions that were roughly 21% wetter and ~7°C cooler. These results suggest that regional LGM high stands were caused by a climatic optimum in which moderately wetter conditions combined with depressed temperatures to create a positive hydrologic budget. Later high stands of Lake Bonneville and nearby pluvial lakes were likely achieved under larger increases in precipitation, prior to a transition to drier conditions after ~15 ka.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-381445

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