SGER: Sr, Nd Isotopic Investigation of the Source and Age of Antarctic Surface Salts

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Antarctica's Dry Valleys host abundant salt deposits concentrated in layers within soil profiles or in evaporative lakes, and also on the undersides of cobbles. These cobbles rest on modern and ancient surfaces, some buried and preserved by deposits at least 15 million years old. This work will 1) investigate the possibility that these salts, and the processes responsible for their formation and preservation, may be directly dated by the Rb/Sr isochron method; and 2) investigate the source(s) of the cations specifically in surface cobble salts by means of Sr (and Nd) isotopic analysis. If these salts can be dated, the technique will provide a new means of dating paleo-surfaces to aid in stratigraphic, paleontologic, geomorphic, and paleo-climatologic interpretations. The salts could also be used to date pulses of increased weathering and/or precipitation during which the salts were formed, and since which the salts were preserved. This potential geochronometer alone would be of great utility to studies of cold desert regions like Antarctica. Depending on the Sr source, there also exists great potential to exploit the archive of modern and ancient surface salts to produce a 15+ million year record of Sr, Nd from atmospheric precipitation and/or from surface weathering processes in Antarctica. This exploratory work is particularly high risk given the limited previous Sr, Nd analysis of these salts and related materials, and because the potential to directly date these salts by Rb/Sr has yet to be explored and evaluated. The broader impacts include new research collaborations and education of graduate and undergraduate students, one of whom is a woman.