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

南极洲干燥的山谷蕴藏着丰富的盐矿，集中在土壤剖面或蒸发湖泊内的各层中，也位于鹅卵石的底部。这些鹅卵石躺在现代和古代的地表上，其中一些被至少1500万年前的沉积物掩埋和保存。这项工作将1)研究这些盐类及其形成和保存过程的可能性，可以用Rb/Sr等时线方法直接测定其年龄；2)用锶(和钕)同位素分析方法研究表层鹅卵石盐类中阳离子的来源(S)。如果可以确定这些盐的年代，这项技术将提供一种新的方法来测定古地表的年龄，以帮助进行地层学、古生物学、地貌学和古气候学解释。盐类还可用于测定盐类形成和保存期间风化和/或降水增加的脉冲时间。这种潜在的地质计时器本身就对研究南极洲等寒冷的沙漠地区非常有用。根据锶的来源，也有很大的潜力利用现代和古代地表盐类档案，从南极大气降水和/或地表风化过程中产生1500多万年的锶、钕记录。鉴于以前对这些盐和相关材料进行的锶、钕分析有限，这项探索性工作的风险特别高，而且还没有探索和评估利用Rb/锶直接确定这些盐的年代的可能性。更广泛的影响包括新的研究合作以及对研究生和本科生的教育，其中一名是女性。

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.