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

南极洲的干谷拥有丰富的盐矿，这些盐矿集中在土壤剖面或蒸发湖的层中，也存在于鹅卵石的底部。这些鹅卵石分布在现代和古代的表面上，有些是由至少1500万年的沉积物掩埋和保存的。这项工作将：(1)研究这些盐及其形成和保存过程的可能性，可以通过Rb/Sr等时线方法直接确定年代；2)通过Sr（和Nd）同位素分析研究表面鹅卵石盐中阳离子的来源。如果能测定这些盐的年代，这项技术将提供一种测定古地表年代的新方法，有助于地层学、古生物学、地貌学和古气候学的解释。这些盐还可以用来测定风化和/或降水增加的时间，在这些时间里，盐形成了，因此盐被保存了下来。这种潜在的地球天文仪本身就对研究像南极洲这样的寒冷沙漠地区有很大的用处。根据Sr来源的不同，利用现代和古代地表盐的档案，从大气降水和/或南极洲的表面风化过程中获得1500多万年的Sr， Nd记录也存在很大的潜力。鉴于之前对这些盐和相关材料的Sr、Nd分析有限，而且通过Rb/Sr直接确定这些盐的年代的潜力尚未得到探索和评估，因此这项探索性工作的风险尤其高。更广泛的影响包括新的研究合作和研究生和本科生的教育，其中一名学生是女性。

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.