Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Planets. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]Properties of the Nili Fossae Olivine-clay-carbonate lithology: orbital and in situ at SéítahAuthorsAdrian JonBrowniDLinda CKahLuciaMandoniDRoger C.WiensPatrick C.PinetiDEliseClavéStephaneLe MoueliciDAryaUdryiDPatrick JGasdaClementRoyeriDKeyronHickman-LewisAgnèsCousinJustin ISimonEdwardCloutisiDThierryFouchetiDAlbertoFairenStephanieConnellDavid TimothyFlanneryBriony Heather NoelleHorganiDLisaMayhewAllan H.TreimaniDJorge I.NúñezBrittan ValhallaWogslandHans E. F.AmundsenCathyQuantin-NatafKevin PeterHandVincianeDebailleAriEssunfeldPierreBeckNicholasToscaiDJuan ManuelMadariagaiDEleni MariaRavanisKarimBenzeraraJadeComellasOlivierForniSee all authors Adrian Jon BrowniDCorresponding Author• Submitting AuthorPlancius ResearchiDhttps://orcid.org/0000-0002-9352-6989view email addressThe email was not providedcopy email addressLinda C KahUniversity of Tennessee at Knoxvilleview email addressThe email was not providedcopy email addressLucia MandoniDLaboratoire de Géologie de LyoniDhttps://orcid.org/0000-0002-9310-0742view email addressThe email was not providedcopy email addressRoger C. WiensLos Alamos National Laboratory (DOE)view email addressThe email was not providedcopy email addressPatrick C. PinetiDUniv. de Toulouse / CNRSiDhttps://orcid.org/0000-0002-1933-5631view email addressThe email was not providedcopy email addressElise ClavéUniversity of Bordeauxview email addressThe email was not providedcopy email addressStephane Le MoueliciDLPGNiDhttps://orcid.org/0000-0001-5260-1367view email addressThe email was not providedcopy email addressArya UdryiDDepartment of Geoscience, University of Nevada, Las VegasiDhttps://orcid.org/0000-0002-0074-8110view email addressThe email was not providedcopy email addressPatrick J GasdaLos Alamos National Laboratory (DOE)view email addressThe email was not providedcopy email addressClement RoyeriD4LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris,iDhttps://orcid.org/0000-0002-5472-7235view email addressThe email was not providedcopy email addressKeyron Hickman-LewisThe Natural History Museumview email addressThe email was not providedcopy email addressAgnès CousinInstitut de Recherche en Astrophysique et Planétologie - IRAPview email addressThe email was not providedcopy email addressJustin I SimonNational Aeronautics and Space Administration (NASA)view email addressThe email was not providedcopy email addressEdward CloutisiDUniversity of WinnepegiDhttps://orcid.org/0000-0001-7301-0929view email addressThe email was not providedcopy email addressThierry FouchetiDObservatoire de ParisiDhttps://orcid.org/0000-0001-9040-8285view email addressThe email was not providedcopy email addressAlberto FairenCentro de Astrobiologiaview email addressThe email was not providedcopy email addressStephanie ConnellPurdue Universityview email addressThe email was not providedcopy email addressDavid Timothy FlanneryScience and Engineering Faculty, Queensland University of Technologyview email addressThe email was not providedcopy email addressBriony Heather Noelle HorganiDPurdue UniversityiDhttps://orcid.org/0000-0001-6314-9724view email addressThe email was not providedcopy email addressLisa MayhewUniversity of Colorado Boulderview email addressThe email was not providedcopy email addressAllan H. TreimaniDLunar and Planetary InstituteiDhttps://orcid.org/0000-0002-8073-2839view email addressThe email was not providedcopy email addressJorge I. NúñezJohns Hopkins University Applied Physics Laboratoryview email addressThe email was not providedcopy email addressBrittan Valhalla WogslandUniversity of Tennesseeview email addressThe email was not providedcopy email addressHans E. F. AmundsenEarth and Planetary Exploration Servicesview email addressThe email was not providedcopy email addressCathy Quantin-Nataflaboratoire de Géologie de Lyonview email addressThe email was not providedcopy email addressKevin Peter HandJet Propulsion Laboratoryview email addressThe email was not providedcopy email addressVinciane DebailleUniversité Libre de Bruxellesview email addressThe email was not providedcopy email addressAri EssunfeldLos Alamos National Laboratoryview email addressThe email was not providedcopy email addressPierre BeckInstitut de Planétologie et d'Astrophysique de Grenoble, Université Joseph Fourier, Grenoble, Franceview email addressThe email was not providedcopy email addressNicholas ToscaiDUniversity of CambridgeiDhttps://orcid.org/0000-0003-4415-4231view email addressThe email was not providedcopy email addressJuan Manuel MadariagaiDUniversity of the Basque CountryiDhttps://orcid.org/0000-0002-1685-6335view email addressThe email was not providedcopy email addressEleni Maria RavanisDepartment of Earth Sciences, University of Hawai'i, Honolulu, HI, USAview email addressThe email was not providedcopy email addressKarim BenzeraraInstitut de Minéralogie, Physique des Matériaux et Cosmochimie, CNRSview email addressThe email was not providedcopy email addressJade ComellasUniversity of Hawai'i at Mānoaview email addressThe email was not providedcopy email addressOlivier ForniInstitut de Recherche en Astrophysique et Planétologie (IRAP) - CNRSview email addressThe email was not providedcopy email address
Abstract The first samples collected by the Perseverance rover on the Mars 2020 mission were from the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory analysis of these samples back on Earth would provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero crater. However, interpreting these samples requires a detailed understanding of the emplacement and modification history of the Maaz formation. Here we synthesize rover and orbital remote sensing data to link outcrop‐scale interpretations to the broader history of the crater, including Mastcam‐Z mosaics and multispectral images, SuperCam chemistry and reflectance point spectra, Radar Imager for Mars' subsurface eXperiment ground penetrating radar, and orbital hyperspectral reflectance and high‐resolution images. We show that the Maaz formation is composed of a series of distinct members corresponding to basaltic to basaltic‐andesite lava flows. The members exhibit variable spectral signatures dominated by high‐Ca pyroxene, Fe‐bearing feldspar, and hematite, which can be tied directly to igneous grains and altered matrix in abrasion patches. Spectral variations correlate with morphological variations, from recessive layers that produce a regolith lag in lower Maaz, to weathered polygonally fractured paleosurfaces and crater‐retaining massive blocky hummocks in upper Maaz. The Maaz members were likely separated by one or more extended periods of time, and were subjected to variable erosion, burial, exhumation, weathering, and tectonic modification. The two unique samples from the Maaz formation are representative of this diversity, and together will provide an important geochronological framework for the history of Jezero crater.
Refined calibrations of CRISM images are enabling identification of smaller deposits of unique aqueous materials on Mars that reveal changing environmental conditions at the region surrounding Mawrth Vallis. Through characterization of these clay-sulfate assemblages and their association with the layered, phyllosilicate units of this region, more details of the aqueous geochemical history can be gleaned. A stratigraphy including five distinct mineral horizons is mapped using compositional data from CRISM over CTX and HRSC imagery across 100s of km and from CRISM over HiRISE imagery across 100s of meters. Transitions in mineralogic units were characterized using visible/near-infrared (VNIR) spectral properties and surface morphology. We identified and characterized complex "doublet" type spectral signatures with two bands between 2.2 and 2.3 μm at one stratigraphic horizon. Based on comparisons with terrestrial sites, the spectral "doublet" unit described here may reflect the remnants of a salty, evaporative period that existed on Mars during the transition from formation of Fe-rich phyllosilicates to Al-rich phyllosilicates. Layered outcrops observed at Mawrth Vallis are thicker than in other altered regions of Mars, but may represent processes that were more widespread in wet regions of the planet during its early history. The aqueous geochemical environments supporting the outcrops observed here include: (i) the formation of Fe3+-rich smectites in a warm and wet environment, (ii) overlain by a thin ferrous-bearing clay unit that could be associated with heating or reducing conditions, (iii) followed by a transition to salty and/or acidic alteration phases and sulfates (characterized by the spectral "doublet" shape) in an evaporative setting, (iv) formation of Al-rich phyllosilicates through pedogenesis or acid leaching, and (v) finally persistence of poorly crystalline aluminosilicates marking the end of the warm climate on early Mars. The "doublet" type units described here are likely composed of clay-sulfate assemblages formed in saline, acidic evaporative environments similar to those found in Western Australia and the Atacama desert. Despite the chemically extreme and variable waters present at these terrestrial, saline lake environments, active ecosystems are present; thus, these "doublet" type units may mark exciting areas for continued exploration important to astrobiology on Mars.
