Abstract DGP2026-75

The western delta in Jezero crater is well-known due to the ongoing NASA Mars 2020 Mission and Perseverance rover, which has been collecting samples from the delta and is now exploring the region further to the west. However, Jezero crater also hosts a second delta to the north, which is less explored but also relevant for understanding the hydrological evolution of the Jezero paleolake.

The appearance of the northern delta is not homogenous: the northern part, which is closer to the northern inlet, is eroded and full of local depressions with dark material, while the southern part is well-preserved and exposes prominent sedimentary layering. In our study, we analysed the morphology of the northern delta in order to determine the geological processes that have shaped its present appearance and to explain the morphological difference between its northern and southern parts. We conducted morphological mapping with 1:10000 scale using HiRISE data (McEwen et al., 2007). Eleven units were identified: 1) arealy extended features: eroded bright unit, layered bright unit, dark floor, light-toned floor, transverse aeolian ridge (TAR) fields, ripple fields; and 2) individual features: distinct layers, indistinct layers, lineaments, craters, buttes. Each mapped unit was first analyzed separately: we traced the origin of the dark material in TARs, observed gradual transformation and obliteration of the sedimentary layers from south to north, clarified the origin of the lineaments, and performed crater distribution analysis. Synthesizing these observations led to a scenario of the delta’s transformation. First, the fluvial sediment transport and water level fluctuations formed and defined the delta body configuration and sedimentary layering (including dark layers, which are presumably re-deposited volcanic ash from outside). After that, with the final lake regression, the surface was exposed to the atmosphere, allowing resurfacing by aeolian erosion (forming TARs, ripples and desiccation cracks) and impact cratering. Based on our analysis and previous studies (Ovchinnikova et al., 2025; Mangold et al., 2024; Horgan et al., 2020), we also identified three scenarios to explain the morphological difference between the northern and southern parts of the delta:

1) the southern part is covered by an erosion-resistant LCP (low calcium pyroxene) unit, which served as protection against degradation;

2) the southern part of the delta was exposed to the atmosphere later than the northern part, and was protected by the water level from aeolian erosion and impact cratering;

3) the southern part experienced weaker wind erosion than the northern part.

 

References:

Horgan, B. H. N., et al. (2020). The mineral diversity of Jezero crater: Evidence for possible lacustrine carbonates on Mars. Icarus, 339. https://doi.org/10.1016/j.icarus.2019.113526

Mangold, N., et al. (2024). Past variations of water level of Jezero paleolake. In: 55th Lunar and Planetary Science Conference

McEwen, A. S., et al. (2007). Mars reconnaissance orbiter’s high resolution imaging science experiment (HiRISE). Journal of Geophysical Research: Planets, 112(5). https://doi.org/10.1029/2005JE002605

Ovchinnikova, A., et al. (2026). Influence of the western inlet on the northern delta in Jezero crater, Mars: Topographic-compositional analysis and sediment transport modeling. Icarus, 445. https://doi.org/10.1016/j.icarus.2025.116840