¹Briony Horgan et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007612]
¹Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West 19 Lafayette, IN 47906
Published by arrangement with John Wiley & Sons

The first samples collected by the Perseverance rover on the Mars 2020 mission were from 60 the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory 61 analysis of these samples back on Earth would provide important constraints on the petrologic 62 history, aqueous processes, and timing of key events in Jezero crater. However, interpreting 63 these samples requires a detailed understanding of the emplacement and modification history of 64 the Maaz formation. Here we synthesize rover and orbital remote sensing data to link outcrop-65 scale interpretations to the broader history of the crater, including Mastcam-Z mosaics and 66 multispectral images, SuperCam chemistry and reflectance point spectra, RIMFAX ground 67 penetrating radar, and orbital hyperspectral reflectance and high-resolution images. We show 68 that the Maaz formation is composed of a series of distinct members corresponding to basaltic to 69 basaltic-andesite lava flows. The members exhibit variable spectral signatures dominated by 70 high-Ca pyroxene, Fe-bearing feldspar, and hematite, which can be tied directly to igneous 71 grains and altered matrix in abrasion patches. Spectral variations correlate with morphological 72 variations, from recessive layers that produce a regolith lag in lower Maaz, to weathered 73 polygonally fractured paleosurfaces and crater-retaining massive blocky hummocks in upper 74 Maaz. The Maaz members were likely separated by one or more extended periods of time, and 75 were subjected to variable erosion, burial, exhumation, weathering, and tectonic modification. 76 The two unique samples from the Maaz formation are representative of this diversity, and 77 together will provide an important geochronological framework for the history of Jezero crater.