Depositional record of the Bonneville Salt Flats in the past 40 thousand years
–Jeremiah A. Bernau, Brenda B. Bowen
I am a PhD candidate working with Dr. Brenda Bowen on the Bonneville Salt Flats. My research focuses on water movement on diurnal to millennial timescales in arid settings. I hope to use my research to inform resource and landscape management decisions as water resources change with climate change.
The Bonneville Salt Flats (BSF) is a valued and rapidly changing landscape. Much remains unknown about its age and the conditions it formed under. We aim to inform landscape management decisions and provide context for modern saline pan changes by determining its depositional history. We test two hypotheses. Hypothesis 1, which is the prevailing depositional model, is that BSF formed from the desiccation of Lake Bonneville with a climatic shift from moist to arid. Hypothesis 2 is that BSF formed after climate shifted from highly arid to cool and moist. After examining cores for evidence of Lake Bonneville sediments and dating core material, we concluded that hypothesis 2 is correct. Before Lake Bonneville, there was a shallow saline lake at BSF (>40 to 28 ka). Lake Bonneville was a deep, extensive lake from 28 to 15 ka. Because lake Bonneville sediments are absent in cores, we infer widespread deflation from ~10 to 5 ka. Multiple paleoenvironmental records indicate this was an extremely arid period. We found the oldest halite layer at BSF to <5 ka old. These results suggest that as the modern BSF becomes increasingly arid, there is potential for increased dust production and reduced crust extent.