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A > 200 ka U-Th based chronology from lacustrine evaporites, Searles Lake, CA
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  • Justin S. Stroup,
  • Kristian J. Olson,
  • Tim K. Lowenstein,
  • Adam B. Jost,
  • Hayley M. Mosher,
  • Mark D. Peaple,
  • Sarah J. Feakins,
  • Christine Y. Chen,
  • Steven P. Lund,
  • David McGee
Justin S. Stroup
State University of New York at Oswego, State University of New York at Oswego

Corresponding Author:[email protected]

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Kristian J. Olson
Binghamton University, Binghamton University
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Tim K. Lowenstein
Binghamton University, Binghamton University
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Adam B. Jost
Massachusetts Institute of Technology, Massachusetts Institute of Technology
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Hayley M. Mosher
SUNY Oswego, SUNY Oswego
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Mark D. Peaple
University of Southern California, University of Southern California
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Sarah J. Feakins
University of Southern California, University of Southern California
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Christine Y. Chen
Lawrence Livermore National Laboratory, Lawrence Livermore National Laboratory
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Steven P. Lund
University of Southern California, University of Southern California
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David McGee
MIT, MIT
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Abstract

Well-dated lacustrine records are essential to establish the timing and drivers of regional hydroclimate change. Searles Basin, California records the depositional history of a fluctuating saline-alkaline lake in the terminal basin of the Owens River system draining the eastern Sierra Nevada. Here we establish a U-Th chronology for the ~76-m-long SLAPP-SLRS17 core collected in 2017 based on dating of evaporite minerals. 98 dated samples comprising 9 different minerals were evaluated based on stratigraphic, mineralogic, textural, chemical and reproducibility criteria. After application of these criteria, a total of 37 dated samples remained as constraints for the age model. A lack of dateable minerals between 145 - 110 ka left the age model unconstrained over the penultimate glacial termination (Termination II). We thus established a tie point between plant wax δD values in the core and a nearby speleothem δ18O record at the beginning of the Last Interglacial. We construct a Bayesian age model allowing stratigraphy to inform sedimentation rate inflections. We find the >210 ka SLAPP-SRLS17 record contains five major units that correspond with prior work. The new dating is broadly consistent with previous efforts but provides more precise age estimates and a detailed evaluation of evaporite depositional history. We also offer a substantial revision of the age of the Bottom Mud-Mixed Layer contact, shifting it from ~130 ka to 178±3 ka. The new U-Th chronology documents the timing of mud and salt layers and lays the foundation for climate reconstructions.