Compositionally and density stratified igneous terrain in Jezero crater, Mars

Before Perseverance, Jezero crater's floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification.The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which also express olivine disequilibrium. Alteration materials including carbonates, sulfates, perchlorates, hydrated silicates, and iron oxides are pervasive but low in abundance, suggesting relatively brief lacustrine conditions. Orbital observations link the Jezero floor lithology to the broader Nili-Syrtis region, suggesting that density-driven compositional stratification is a regional characteristic. Funding was provided by the following sources: NASA's Mars exploration program, including contracts NNH15AZ24I and NNH13ZDA018O to LANL. LANL LDRD code XWHW contributed to calibrations. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). NASA RSSPS grants supported J.I.S., grantnumber 80NSSC20K0239 supported L. Hausrath, grant number 80NSSC20K0240 supported L. Mayhew, and grant number 80NSSC21K0330 supported A.U. CNRS and CNES supported the work in France. DLR supported S.Sc. and D.S.V. The Swedish National Space Agency (contracts 137/19 and 2021-00092) supported S.Si. The Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canadian Space Agency (CSA) supported E.C., S.C., and N.T. The Ministry of Economy and Competitiveness (MINECO, SPAIN) grant PID2019-107442RB-C31 supported F.R., G.L.R., J.A.M., and M.