Abstract EANA2025-128

Chloride-bearing terrains on Mars, particularly those identified in Icaria Planum, are key indicators of past liquid water activity and thus crucial to understanding the planet’s potential for past habitability. These deposits, which likely formed during late-stage aqueous processes, have prompted the search for terrestrial analogs that might offer insights into their formation mechanisms and astrobiological significance.

In this study, we compare the chloride deposits in Icaria Planum with those of the Uyuni Salt Flat in Bolivia, the world's largest salt flat. Despite superficial morphological similarities, such as polygonal fractures and evaporitic crusts, our analysis reveals important differences in depositional context, topography, and hydrological processes. Martian chlorides form in sloped regions associated with episodic surface runoff and shallow perched brines. In contrast, Uyuni’s chloride deposits result from long-term surface and groundwater accumulation within a closed endorheic basin, where inflows from surrounding highlands converge and evaporate under arid conditions in an exceptionally flat terrain.

These differences suggest that Uyuni may not represent a direct analog for the genesis of Martian chlorides. However, its extreme environmental conditions, high UV radiation, hypersalinity, and aridity still make it a valuable terrestrial site for studying microbial survival in conditions relevant to Mars. This comparative approach highlights the importance of critically assessing analog sites not only for geomorphological similarity but also for the processes that shaped them when evaluating the past habitability of Martian environments.