DEPOSITIONAL, DIAGENETIC, AND HABITABILITY CLUES FROM PETROGRAPHY OF SULFATE-RICH CLASTIC ROCKS AT JEZERO CRATER, MARS

The Mars 2020 Perseverance rover has analyzed and sampled siltstones and fine sandstones that contain multiple phases of sulfate minerals. The Hogwallow Flats Member and Yori Pass outcrop, both part of the middle Shenandoah formation of the Jezero crater western fan front, are clastic rocks enriched in several types of sulfate minerals, including anhydrite, hydrated Ca-sulfate, Mg-Fe sulfates, and ferric sulfates. It is likely that some silt and sand grains are reworked sulfate crystals, which may have been eroded, transported, and deposited by physical subaqueous and/or subaerial processes. Images of abraded patches Berry Hollow (of Hogwallow Flats member) and Uganik Island (of Yori Pass outcrop) show diagenetic features including intergranular, overgrowth, vein, and vug cements. Phyllosilicates and Fe-oxide concretions, as well as possible chloride and carbonate, have also been detected in these rocks. Fluorescence signals associated with the sulfates are suggestive of organic matter or trace amounts of cerium in the sulfate minerals. These rocks had multiple saline fluid flow events. We propose that samples from Hogwallow Flats and Yori Pass, if brought to Earth in the future by the Mars Return Sample mission, should be further investigated with petrography, as well as chemical and biological methods, to refine understanding of potential habitability and to search for biosignatures.