Mapping and Characterizing the Northern Fan Deposits in Jezero Crater, Mars

The northern inlet channel to Jezero crater (Sava Vallis) terminates in a fan-shaped depositional feature, part of which blends into the separate well-known western fan delta that is the field site for the NASA Mars 2020 mission’s Perseverance rover. Jezero’s northern fan potentially represents either a second fan delta within the crater or a distal portion of the western fan. To constrain the fluvial and sedimentological history of Jezero and place the rover's in situ observations in proper geologic context, we photogeologically map the northern fan deposits at a lower mapping scale than previous studies, and using ground-based imaging from the Perseverance rover for context. Fifteen geologic units are subdivided based on HiRISE-based interpretations of sedimentary facies and associated depositional processes, as well as crosscutting age relationships. Mapped units are also defined based on orbital data from CRISM and THEMIS to assess their compositional signatures. We interpret the northern fan deposits as older than the uppermost blocky unit in the western fan delta. We also conclude that the eastern portion of the northern fan deposits show evidence of fluvial deposition from Sava Vallis, while part of its western side could represent a distal part of the western fan delta. We synthesize our observations and interpretations to present several scenarios for the deposition of the northern and western fans which can aid in characterizing the crater’s watersheds as well as placing this depositional activity into stratigraphic context within the broader Isidis Basin region.