Clumped isotope constraints on changes in latest Pleistocene hydroclimate in the northwestern Great Basin: Lake Surprise, California

Journal Article · Mon May 04 00:00:00 EDT 2020 · Geological Society of America, Bulletin

DOI:https://doi.org/10.1130/b35484.1· OSTI ID:1851341

Santi, L. M. ^[1]; Arnold, A. J. ^[2]; Ibarra, D. E. ^[3]; Whicker, C. A. ^[4]; Mering, J. A. ^[5]; Lomarda, R. B. ^[6]; Lora, J. M. ^[5]; Tripati, A. ^[7]

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1. Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA; Center for Diverse Leadership in Science, University of California, Los Angeles, California 90095, USA; Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA; GSI Environmental Inc., 19200 Von Karman Avenue Suite 800, Irvine, California 92612, USA
2. Center for Diverse Leadership in Science, University of California, Los Angeles, California 90095, USA; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA
3. Department of Geological Sciences, Stanford University, Stanford, California 94305, USA
4. Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA
5. Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA
6. Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA; Center for Diverse Leadership in Science, University of California, Los Angeles, California 90095, USA
7. Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA; Center for Diverse Leadership in Science, University of California, Los Angeles, California 90095, USA; Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA

Abstract During the Last Glacial Maximum (LGM) and subsequent deglaciation, the Great Basin in the southwestern United States was covered by numerous extensive closed-basin lakes, in stark contrast with the predominately arid climate observed today. This transition from lakes in the Late Pleistocene to modern aridity implies large changes in the regional water balance. Whether these changes were driven by increased precipitation rates due to changes in atmospheric dynamics, decreased evaporation rates resulting from temperature depression and summer insolation changes, or some combination of the two remains uncertain. The factors contributing to these large-scale changes in hydroclimate are critical to resolve, given that this region is poised to undergo future anthropogenic-forced climate changes with large uncertainties in model simulations for the 21st century. Furthermore, there are ambiguous constraints on the magnitude and even the sign of changes in key hydroclimate variables between the Last Glacial Maximum and the present day in both proxy reconstructions and climate model analyses of the region. Here we report thermodynamically derived estimates of changes in temperature, precipitation, and evaporation rates, as well as the isotopic composition of lake water, using clumped isotope data from an ancient lake in the northwestern Great Basin, Lake Surprise (California). Compared to modern climate, mean annual air temperature at Lake Surprise was 4.7 °C lower during the Last Glacial Maximum, with decreased evaporation rates and similar precipitation rates to modern. During the mid-deglacial period, the growth of Lake Surprise implied that the lake hydrologic budget briefly departed from steady state. Our reconstructions indicate that this growth took place rapidly, while the subsequent lake regression took place over several thousand years. Using models for precipitation and evaporation constrained from clumped isotope results, we determine that the disappearance of Lake Surprise coincided with a moderate increase in lake temperature, along with increasing evaporation rates outpacing increasing precipitation rates. Concomitant analysis of proxy data and climate model simulations for the Last Glacial Maximum are used to provide a robust means to understand past climate change, and by extension, predict how current hydroclimates may respond to expected future climate forcings. We suggest that an expansion of this analysis to more basins across a larger spatial scale could provide valuable insight into proposed climate forcings, and aid in climate model process depiction. Ultimately, our analysis highlights the importance of temperature-driven evaporation as a mechanism for lake growth and retreat in this region.

• Research Organization: Univ. of California, Los Angeles, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: SC0010288
• OSTI ID: 1851341
• Journal Information: Geological Society of America, Bulletin, Vol. 132, Issue 11-12; ISSN 0016-7606
• Publisher: Geological Society of America
• Country of Publication: United States
• Language: English

Related Subjects

Geology