The Mineralogy and Cation Exchange of Sediments in Don Juan Pond, Antarctica Dry Valley: Implications for Mars

Located in the McMurdo Dry Valleys of Antarctica (MDV) is among of the saltiest bodies of water of Earth, Don Juan Pond (DJP)[1]. DJP pond waters are unique in that they contain nearly 40% salt by weight including 95% CaCl2 [1-5] and they never evaporate or freeze entirely due to the high hygroscopicity and low eutectic temperature of the CaCl2 brine (-52 ̊C) [6]. The source of DJP water is suggested to be due to groundwater upwelling through a weathered dolerite aquifer and/or near-surface runoff, including salt deliquescence in the pond’s watershed [7,8], however the source of water is still a topic of study. During the 2017-2018 field season, we collected soil samples and altered sediments on hillslopes and drainage basins near the pond (Fig. 1). Two drill bores were also acquired in Don Juan Pond sediments in a episodically flooded area of the pond basin. This study's objectives were to characterize the mineralogy of these soils and sediments to determine if there are mineralogical indicators and/or controls for the delivery of salts to DJP and understand the role of salts on Mars on these analog studies.