Occurrences of possible hydrated sulfates in the southern high latitudes of Mars

• Results expand known areas exhibiting hydration in the southern high latitudes.
• Strongest spectral features located on putative volcanoes indicate Ca-sulfates.
• Hydrates found in all study regions showing a ubiquitous process for formation.
• Hydrates appear where the shallow subsurface is exposed through periglacial processes.

Hydrated sulfate minerals record the history of water and habitable environments on Mars, yet prior studies of them have neglected a vast region surrounding the planet’s south pole. Some of the few sulfates reported there are localized to putative ancient volcanoes that may have erupted under an ice sheet, possibly forming sulfates via hydrothermal alteration. Alternatively, sulfates may have formed more recently from sunlight causing minor melting of polar ices and the weathering of embedded dust particles, a process thought to explain the sulfates found near Mars’ north pole. To test these hypotheses, we searched for southern high-latitude sulfates using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO), focusing on regions that include putative volcanoes or geologically similar landforms. In 217 targeted images, we used spectral parameters to identify regions of interest from which we extracted spectra. The spectra were then visually compared to laboratory spectra to identify possible hydrated mineral constituents. In this paper, we present spectra from 16 of the images and statistics derived from the full set of 217, along with spectra from one mapping tile. We find that hydrated sulfates are found throughout the southern high latitudes suggesting a ubiquitous process for hydrated mineral formation and/or the relocation of hydrated minerals due to a long history of impacts, aeolian transport, weathering and periglacial processes.