Brine-driven destruction of clay minerals in Gale crater, Mars

Creators: Bristow, T. F.; Grotzinger, J. P.; Rampe, E. B.; Cuadros, J.; Chipera, S. J.; Downs, G. W.; Fedo, C. M.; Frydenvang, J.; McAdam, A. C.; Morris, R. V.; Achilles, C. N.; Blake, D. F.; Castle, N.; Craig, P.; Des Marais, D. J.; Downs, R. T.; Hazen, R. M.; Ming, D. W.; Morrison, S. M.; Thorpe, M. T.; Treiman, A. H.; Tu, V.; Vaniman, D. T.; Yen, A. S.; Gellert, R.; Mahaffy, P. R.; Wiens, R. C.; Bryk, A. B.; Bennett, K. A.; Fox, V. K.; Millken, R. E.; Fraeman, A. A.; Vasavada, A. R.

Abstract

Mars' sedimentary rock record preserves information on geological (and potential astrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars. A traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago. We report spatial differences in the mineralogy of time-equivalent sedimentary rocks <400 meters apart. These differences indicate localized infiltration of silica-poor brines, generated during deposition of overlying magnesium sulfate–bearing strata. We propose that destabilization of silicate minerals driven by silica-poor brines (rarely observed on Earth) was widespread on ancient Mars, because sulfate deposits are globally distributed.

Additional Information

© 2021 American Association for the Advancement of Science. This is an article distributed under the terms of the Science Journals Default License. Received 24 January 2021; accepted 28 May 2021. We thank R. Kleeberg for help developing the CheMin instrument profile model for BGMN and A. Derkowski for informative discussion. J. C. Corona kindly provided XRD data from Fe talc, and P. De Deckker shared knowledge of Australian lakes. We thank J. Bishop and two anonymous reviewers for helping improve the manuscript. We acknowledge the support of the Jet Propulsion Lab engineering and management teams and MSL science team members who participated in tactical and strategic operations, without whom the data presented here could not have been collected. Some of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). A.A.F., A.C.M., and C.M.F. acknowledge funding by the MSL Participating Scientist Program, NASA solicitation NNH15ZDA001N. J.F. acknowledges support from the Carlsberg Foundation. J.P.G. received additional funding from the Simons Collaboration for the Origin of Life. Author contributions: T.F.B. wrote the manuscript, with corrections, discussions, and/or revised text from coauthors. J.C. led one-dimensional modeling of clay minerals. S.J.C. quantified the abundances of clay minerals and the x-ray amorphous phase from CheMin XRD data. G.W.D. led efforts to identify the 9.22-Å phase from XRD data. C.M.F. led efforts to establish the relationships between rock strata exposed at VRR and GT, capturing them in Figs. 1 and 2. J.F. analyzed ChemCam Li data and helped produce Fig. 2. A.C.M. led the interpretation of SAM EGA data and helped produce Fig. 4 and fig. S4. A.S.Y. compiled the bulk geochemical data from the Alpha Particle X-ray Spectrometer shown in table S1 and used to generate fig. S5. R.V.M. compiled the XRD data used to determine the angular resolution of the CheMin instrument (fig. S2). R.E.M. led comparisons of orbital and ground-based mineral data. C.N.A., T.F.B., D.W.M., S.M.M., E.B.R., M.T.T., V.T., and D.T.V. determined the abundances of crystalline phases in GT samples from XRD data. D.F.B., A.B.B., K.A.B., A.A.F., V.K.F., R.G., J.P.G., P.R.M., E.B.R., D.T.V., R.C.W., and A.R.V. designed the rover instruments and guided the mission. All authors performed operational roles in data collection. Competing interests: V.K.F. is also affiliated with the Department of Physics and Astronomy, Carleton College, Northfield, MN 55057, USA. Data and materials availability: All Curiosity data presented in this paper are archived in NASA's Planetary Data System; the URLs and file identifications are listed in table S5. The software written by the authors of this paper and files needed to replicate the analyses are publicly available at Dryad (51).

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