Finescale Sedimentary Architecture of the Upper Part of the Jezero Western Delta Front

Orbital 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 river delta that built into an ancient lake basin during the Late NoachianEarly Hesperian epochs on Mars (~3.63.8 Ga) [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 only obtaining a few remote sensing observations along the way. In April 2022, the rover arrived at the base of the ancient delta in the Three Forks region of the crater floor adjacent to the delta front (Fig. 1). During the ‘rapid traverse’ and the exploration of two sections at the delta front Cape Nukshak and Hawksbill Gap – Perseverance obtained striking images from the MastcamZ and SuperCam’s Remote MicroImager instruments of the stratigraphy exposed stratigraphically higher up in the fan’s erosional front [3]. Images provide new views of the stratigraphy exposed in the erosional front of the western Jezero delta; in particular, showing sections 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 fan deposits, and therefore paleoenvironmental implications.