Estimated Minimum Life Span of the Jezero Fluvial Delta (Mars)

Abstract

The paleo-lake floor at the edge of the Jezero delta has been selected as the NASA 2020 rover landing site. In this article, we demonstrate the sequences of lake filling and delta formation and constrain the minimum life span of the Jezero paleo-lake from sedimentological and hydrological analyses. Two main phases of delta evolution can be recognized by utilizing imagery provided by the High Resolution Imaging Science Experiment (NASA Mars Reconnaissance Orbiter) and High Resolution Stereo Camera (ESA Mars Express): (1) basin infilling before the breaching of the Jezero rim and (2) the delta formation itself. Our results suggest that delta formation occurred over a minimum period of 90-550 years of hydrological activity. Breaching of the Jezero rim occurred in at least three distinct episodes, which spanned a far longer time-period than overall delta formation. This evolutionary history implies that the Jezero-lake floor would have been a haven for fine-grained sediment accumulation and hosted an active environment of significant astrobiological importance.

Fluvial Regimes, Morphometry, and Age of Jezero Crater Paleolake Inlet Valleys and Their Exobiological Significance for the 2020 Rover Mission Landing Site

“…To provide conservative values, we use these lowest bounds to provide a channel height that is not overestimated in the three locations considered (rounded to the closest integer, results give 5 m at 200 m width and 10 m at 500 m width). These values are consistent with recent scaling relationships introduced by Konsoer et al (2018) and with the value measured from a terrace at the channel entrance into the Jezero crater by Salese et al (2019a), estimated to be 5 m depth for a width of 190 m.…”

“…We analyzed the morphometry of the valley networks, including transverse and longitudinal profiles, estimated discharge rates of observed channels, and analyzed their stratigraphic relationships with surrounding landforms and lithological units. These results provide new constraints on the formation of the fan-deltas in Jezero, including the age and timescale of the paleolake activity, whereas a new study focused on the delta formation will further estimate the minimum lifespan of the Jezero delta (Salese et al, 2019a(Salese et al, , 2020 by using hydrological models from the work of Kleinhans (2005Kleinhans ( , 2010. We conclude our study with a summary of the exobiological implications of our results for the Mars 2020 Perseverance rover's exploration in the Jezero crater.…”

“…In addition, no HiRISE stereo images are available in key locations where the elongated landforms interpreted as fluvial bars are observed, those being too small for the HRSC DEM resolution. A 5 m-high terrace was observed at the entrance into the Jezero crater (Salese et al, 2019a) that can act as a local height for the entrance channel. For the other locations, we base our estimations on empirical laws.…”

“…More in-depth modeling of the discharge rates using the channels at the entrance of Jezero crater has been done by Salese et al (2019aSalese et al ( , 2020. Results give durations of the hydrological activity leading to the formation of the fandelta in hundreds of years (90-550 years) with varying parameters.…”

“…This valley decreases in width with distance to its end. The outlet valley was not investigated in this work but has been included in a numerical model and an evolutionary scenario of Jezero basin (Salese et al, 2019a). This valley is generally interpreted as due to short-duration episode(s) related to the breach of the crater to the East and corresponding to short release(s) of water (<<100 years, Holo and Kite, 2017).…”