Fine-scale sedimentary architecture of the upper part of the Jezero western delta front

International audienceOrbital and rover observations of relict geomorphic features and stratigraphic architectures indicate Mars once had a warmer, wetter climate. Constraining the character, relative timing and persistence of ancient aqueous activity on Mars is possible through detailed interrogation of the stratal geometry of aqueously deposited sedimentary bodies. Such analyses inform interpretations of Martian climate evolution, potential habitability, and search strategies for rocks that might contain potential biosignatures. NASA’s Mars 2020 Perseverance rover mission is seeking signs of ancient life in Jezero crater and is collecting a cache of Martian rock and soil samples for planned return to Earth by a future mission.A prominent sedimentary fan deposit at the western margin of Jezero crater has been interpreted to be a riverdelta that built into an ancient lake basin during the Late Noachian-Early Hesperian epochs on Mars (~3.6-3.8Ga) [1, 2]. The Perseverance rover landed on 18 February 2021 ~2.2 km from the western fan. In March-April 2022, the rover conducted a rapid traverse along the eastern and southeastern side of Jezero fan onlyobtaining a few remote sensing observations along the way. In April 2022, the rover arrived at the base of theancient delta in the Three Forks region of the crater floor adjacent to the delta front (Fig. 1). During the ‘rapidtraverse’ and the exploration of two sections at the delta front - Cape Nukshak and Hawksbill Gap –Perseverance obtained striking images from the Mastcam-Z and SuperCam’s Remote Micro-Imagerinstruments of the stratigraphy exposed stratigraphically higher up in the fan’s erosional front [3]. Images providenew views of the stratigraphy exposed in the erosional front of the western Jezero delta; in particular, showingsections of the delta previously not visible from long distance observations and at much higher resolution.Here, we report its stratigraphy and sedimentology, which provide new constraints on the nature of the fandeposits, and therefore paleoenvironmental implications