MAPPING AND INTERPRETING THE NORTHERN FAN DEPOSITS IN JEZERO CRATER, MARS

Jezero crater is a ~50 km Noachian-aged ancient crater lake basin and the landing site for NASA’s Mars 2020 Perseverance rover mission. As such, it is useful to compare the information collected using orbital data with the rover’s in situ observations in order to build a robust understanding of the history of geological processes that occurred in this region. The northern fan deposit within Jezero crater is of particular interest because it is unclear whether it is its own system connected with the northern watershed or related to the western delta (the rover's main target). Previous maps constructed at a lower scale than this study’s map supported the latter interpretation (Goudge et al., 2015; Sun and Stack, 2020). CRISM data show that both the northern fan deposit and the western delta exhibit similar mineral signatures, but the northern fan deposit lacks the low-calcium pyroxene and smectite signatures observed on the top surface of the western fan (Horgan et al., 2020).

To better characterize the history and evolution of fluvio-deltaic processes within Jezero, we are constructing a photogeological map at a 1:3000 digital map scale using ArcMap and HiRISE images. Units are mapped based on morphologic characteristics, such as relative brightness, tone, and surface texture. We also incorporate "ground-truth" for mapped units using images obtained from the Perseverance rover to correlate geologic units identified through ground-based mapping with those in the Jezero landing site map (e.g., Stack et al., 2020). In addition, we use CRISM and THEMIS data to distinguish geological and/or mineralogical differences from the effects of illumination and dust cover variations. Our initial results are consistent with the westernmost part of the northern fan deposit being an extension of the western Jezero delta, although our mapped units grow more morphologically distinct and appear to have more variability towards the east. Our preliminary observations suggest that the northern fan deposits could record the interaction between the furthest reaches of the western delta and a depositional system sourced from the northern channel, rather than being isolated to only one of these two watersheds. However, more detailed study is necessary to further constrain this relationship and to continue to test this hypothesis.

References:

[1] Goudge et al. (2015) JGR, 120, 775-808. [2] Sun and Stack (2020) USGS SIM 3464. [3] Horgan et al. (2020) Icarus, 339, 1-34. [4] Stack et al. (2020) Space Sci. Reviews, 216, 1-47.