EGU23-6593, updated on 09 Jan 2024
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Applying Brillouin thermometry as a novel tool for reconstructing temperatures, depths, and seasonal biases of Holocene/Pleistocene Searles Lake, California

Kristian Olson1, Emmanuel Guillerm2, Mark Peaple3, Tim Lowenstein1, Véronique Gardien2, Frédéric Caupin2, Sarah Feakins3, Jessica Tierney4, Justin Stroup5, Steve Lund3, and David McGee6
Kristian Olson et al.
  • 1Binghamton University, Binghamton, NY, USA
  • 2Université de Lyon, Villeurbanne, France
  • 3University of Southern California, Los Angeles, CA, USA
  • 4University of Arizona, Tucson, AZ, USA
  • 5SUNY Oswego, Oswego, NY, USA
  • 6Massachusetts Institute of Technology, Cambridge, MA, USA

Paleoclimate records from lakes of the southwestern USA have been limited by a lack of independent paleothermometers, resulting in conflicting characterizations of millennial-scale variability in temperature and moisture. Here a novel method called Brillouin thermometry is applied to halite-bearing dry intervals of the late Pleistocene/Holocene (45–0 ka) core record of Searles Lake, California. Halite from the sediment-water interface records lake bottom temperatures during dry, high salinity periods. Analysis of modern saline lakes of various chemistries, depths, climate zones, and mixing regimes shows that: 1) average bottom water temperature is approximately equal to mean annual air temperature, and 2) annual range of bottom water temperature is inversely proportional to lake depth. Brillouin temperatures for eight halite intervals 30.6 ka to 8.5 ka range from 11.8 ± 3.6 to 22.4 ± 3.2 °C. Bottom water temperature variability indicates paleolake depths of ~10 m during halite precipitation. Brillouin thermometric results are then assessed in comparison with two additional temperature proxy records from the same Searles Lake sediment core: 1) branched glycerol dialkyl glycerol tetraethers (brGDGTs) extracted from wet mud intervals, and 2) thermodynamic constraints from evaporite minerals and mineral sequences. Temperatures from brGDGTs for mud intervals 44.7 ka to 3.6 ka range from 13.4 ± 2.8 to 23.9 ± 3.0 °C. Comparisons of Brillouin/brGDGT temperatures with predicted equilibrium temperatures of salt crystallization indicate intervals where seasonal temperature variability forced the dissolution and/or recrystallization of existing temperature-sensitive evaporites. The multiproxy temperature record of Searles Lake agrees with other regional records at glacial/interglacial timescales but displays a wider degree of millennial-scale variability, with temperatures during the last glacial ranging from 8.3 °C below modern mean annual temperatures to 3.8 °C above.

How to cite: Olson, K., Guillerm, E., Peaple, M., Lowenstein, T., Gardien, V., Caupin, F., Feakins, S., Tierney, J., Stroup, J., Lund, S., and McGee, D.: Applying Brillouin thermometry as a novel tool for reconstructing temperatures, depths, and seasonal biases of Holocene/Pleistocene Searles Lake, California, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6593,, 2023.