Diagenesis and clay mineral formationat Gale Crater, Mars

• Published in: Journal of Geophysical Research: Planets
• Main Authors: Bridges, J.C., Schwenzer, S.P., Leveille, Richard, Westall, Frances, Wiens, R. C., Mangold, N., Bristow, T., Edwards, P., Berger, G.
• Other Authors: Space Research Centre Leicester, University of Leicester, Dept. of Physical Sciences, The Open University Milton Keynes (OU), Department of Earth and Planetary Sciences Montréal (EPS), McGill University = Université McGill Montréal, Canada, Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS), Space Remote Sensing Group (ISR-2), Los Alamos National Laboratory (LANL), 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), Exobiology Branch Moffett Field, NASA Ames Research Center (ARC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [CHIM]Chemical Sciences; [SDU]Sciences of the Universe [physics]; Yellowknife; Yellowknife Bay
• Online Access: https://insu.hal.science/insu-01205518; https://insu.hal.science/insu-01205518/document; https://insu.hal.science/insu-01205518/file/jgre20347.pdf; https://doi.org/10.1002/2014JE004757

International audience The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition andalteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of theobserved host rock and alteration minerals, we present results of equilibrium thermochemical modeling ofthe Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondarymineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratoryteam, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formedby the reaction of a CO2-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open systemwith the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rockreacted with the starting fluid) of 100–1000, pH of ~7.5–12. Model alteration assemblages predominantlycontain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that ofsaponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhliteMartian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneousdissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolvingcomposition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.