Chemical Composition of Aqueous Sedimentary Rocks at Gale Crater, Mars

• Main Authors: Mangold, Nicolas, Cousin, Agnès, Dehouck, Erwin, Forni, Olivier, Fraeman, Abigael, Frydenvang, Jens, Gasnault, Olivier, Johnson, Jeffrey, Le Deit, Laetitia, L'Haridon, Jonas, Le Mouélic, Stéphane, Maurice, Sylvestre, Mclennan, Scott, Meslin, Pierre-Yves, Newsom, Horton E., Rapin, William, Rivera-Hernandez, Frances, Salvatore, Mark, Schwenzer, Susanne, Wiens, Roger
• Other Authors: Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement Lyon (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University Applied Physics Laboratory Laurel, MD (APL), Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Meteoritics Albuquerque (IOM), The University of New Mexico Albuquerque, Los Alamos National Laboratory (LANL)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; Rubin; Yellowknife; Yellowknife Bay
• Online Access: https://hal.archives-ouvertes.fr/hal-02411438

International audience The Curiosity rover has traversed 20 km from its landing to the layered rocks of Mt. Sharp (formally named Aeolis Mons), spending >2270 sols (Martian days) at the surface of Mars. In this overview, we provide a summary of the chemical composition along the Murray formation, a >300 m-thick pile of sedimentary rocks present at the base of Mt. Sharp, and dominated by mudstones and fine-grained sandstones interpreted as predominantly lacustrine deposits (Grotzinger et al., Science, 2015). The ChemCam instrument is a laser ablation spectrometer capable of measuring local chemistry (scale of 0.5 mm). Bulk chemistry is derived from the average of several observation points of a given target (after removal of points on soils and diagenetic features). ChemCam is also powerful for identifying the composition of diagenetic features (veins, nodules, concretions, etc.). Along the Murray section, especially the Karasburg and Sutton Island members (sols 1350-1650), the bulk chemistry of Murray Formation presents a low abundance of CaO of 1-2 wt.%, well below the average Mars crust (7-8 wt.%). The Chemical Index of Alteration (CIA) ranges from 50 to 63, suggesting a substantial weathering (as is the case for CIA>50), in agreement with the presence of di-octahedral smectites indicative of surface conditions (from CheMin data, Bristow et al., Science Advances, 2018). These observations indicate weathering in an open system, at or near the surface, contrasting with the results at Yellowknife Bay where mudstones formed in closed system (McLennan et al., Science, 2014). On sol 1750, Curiosity reached the Vera Rubin Ridge (VRR), which is associated with "red hematite" in orbital spectral data (Fraeman et al., JGR, 2013). At this location, ChemCam did not identify a significant enhancement in bulk FeOT abundance. ChemCam detects anomalously high iron abundances (>40 wt.% FeOT) on dark-toned nodules/veins/crystals, locally associated with light-toned Ca-sulfate veins, highlighting their diagenetic ...