GROUND PENETRATING RADAR OBSERVATIONS REVEAL SEDIMENTARY STRUCTURES IN THE MG-CARBONATE BEARING MARGIN UNIT OF JEZERO CRATER, MARS

The Margin Unit in Jezero crater represents an intermediary area between the western fan front and the rim of Jezero crater that is identifiable by its orbital olivine-carbonate composition and rough terrain. Multiple hypotheses exist regarding its formation and evolution, and as it is a significant deposit of Fe-Mg-carbonate, it is likely to record valuable information about past atmospheric conditions, water-rock interactions, and possible signs of life. The NASA Perseverance rover has explored over 6 kilometers of the Margin Unit in ~250 sols with an instrument suite which includes the RIMFAX ground penetrating radar. RIMFAX provides continuous subsurface imaging that probes up to 35 meters below the rover within this geologic unit, which is more than 1.75 times deeper than in previous terrains. As Perseverance traversed the Margin Unit, RIMFAX revealed the presence of ubiquitous subsurface radar features, including layering ranging from sub-meter to hundred meter scales. We interpret the geometry and scale of these features to be most consistent with sedimentary structures, including prominent deltaic foresets which have undergone surficial erosion and later aeolian deposition. Overall, these results imply that the Margin Unit represents a broader fluvial-lacustrine system preserved at depth that was deposited prior to the Jezero western delta fan and may contain significant sedimentary records of possible ancient habitable conditions on Mars.