Emplacement History of Lava Flows of the Máaz Formation on the Jezero Crater Floor: Geochronological Significance and Relationship with the Delta

The Mars 2020 Perseverance rover collected two unique samples from the Máaz formation on the floor of Jezero crater, which is interpreted as a series of ancient aqueously altered lava flows. Geochronological analyses of these samples back on Earth may thus provide critical constraints on the timing of events in Jezero crater. Here we tie MastcamZ and SuperCam data from Perseverance to CRISM and HiRISE orbital data to understand the emplacement history of the Máaz Formation and its relationship with the delta. We find that the rocks sampled within the Maaz formation correspond to distinct lava flows that can be mapped from orbit using morphological and spectral data. The uppermost units at the landing site, the Chtextquoterightal and Nataani members, exhibit the clearest lava morphologies and are strongly oxidized in MastcamZ data. From orbit, this corresponds to a distinct hummocky to smooth flow unit that exhibits CRISM spectra consistent with Febearing feldspar, which Perseverance data shows is due to coarse feldspar in a basaltic andesite flow. This unit retains craters and thus geochronology of samples from the Chtextquoterightal member may be used to better constrain the crater chronology of Mars, if their exhumation histories can be elucidated. These flows overlie the Rochette and Artuby members, basaltic outcrops with highCa pyroxene signatures in MastcamZ data that are interpreted as flows but with enigmatic cmscale layers that could reflect a more complex origin. From orbit, these lower units correspond to fractured blocks in smooth regolith that exhibit highCa pyroxene signatures in CRISM spectra. Spectrally and morphologically similar terrains appear to underlie the delta front from orbit, and RIMFAX radar profiles from Perseverancetextquoterights traverse up the delta front confirm that the delta front overlies this portion of the Máaz formation. Thus, geochronology of samples from the Rochette member may provide constraints on the timing of delta emplacement in Jezero.