The existence of ancient fluvial systems on Mars is widely-accepted, but little is known about how quickly they formed, or what environmental conditions controlled their evolution. We analyzed a sequence of well-preserved inner-bank bar deposits within the meander bends of a multi-stacked sinuous fluvial ridge in Aeolis Dorsa, and compared them to similar features on Earth to establish the conditions required for their formation. Our results reveal that these Martian channels were highly aggradational, rising an order of magnitude higher than terrestrial rivers. This evolution occurred over very rapid timescales, with our estimates suggesting that some entire inner-bar set deposits, and therefore the aggradational channel, may have formed in less than a year, with upper bounds of a few decades. We suggest that this unique channel topography was created by a rapidly-rising downstream water body, triggered by a sequence of externally sourced megafloods (e.g., crater lake breaches).
Ahmed, J., Peakall, J., Balme, M., & Parsons, D. (2022). Rapid megaflood-triggered base-level rise on Mars. Geology, https://doi.org/10.1130/G50277.1