A >200 ka U-Th Based Chronology From Lacustrine Evaporites, Searles Lake, CA
Journal Article
·
· Geochemistry, Geophysics, Geosystems
- State Univ. of New York (SUNY), Oswego, NY (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- State Univ. of New York (SUNY), Binghamton, NY (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- State Univ. of New York (SUNY), Oswego, NY (United States)
- Univ. of Southern California, Los Angeles, CA (United States)
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
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. Ninety-eight dated samples comprising nine different minerals were evaluated based on stratigraphic, mineralogic, textural, chemical, and reproducibility criteria. After the application of these criteria, a total of 37 dated samples remained as constraints for the age model. A lack of dateable minerals between 145 and 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 that 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 enables 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.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 2007291
- Report Number(s):
- LLNL--JRNL-839563; 1060556
- Journal Information:
- Geochemistry, Geophysics, Geosystems, Journal Name: Geochemistry, Geophysics, Geosystems Journal Issue: 3 Vol. 24; ISSN 1525-2027
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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