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.