Chemical alteration of fine-grained sedimentary rocks at Gale crater

N. Mangold, E. Dehouck, C. Fedo, O. Forni, C. Achilles, T. Bristow, R. T. Downs, J. Frydenvang, O. Gasnault, J. L'Haridon, L. Le Deit, S. Maurice, S. M. McLennan, P. Y. Meslin, S. Morrison, H. E. Newsom, E. Rampe, W. Rapin, F. Rivera-Hernandez, M. SalvatoreR. C. Wiens

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

From Sol 750 to 1550, the Curiosity rover documented>100 m thick stack of fine-grained sedimentary rocks making up part of the Murray formation, at the base of Mt Sharp, Gale crater. Here, we use data collected by the ChemCam instrument to estimate the level of chemical weathering in these sedimentary rocks. Both the Chemical Index of Alteration (CIA) and the Weathering Index Scale (WIS) indicate a progressive increase in alteration up section, reaching values of CIA of 63 and WIS of 25%. The increase in CIA and WIS values is coupled with a decrease in calcium abundance, suggesting partial dissolution of Ca-bearing minerals (clinopyroxene and plagioclase). Mineralogy from the CheMin X-ray diffraction instrument indicates a decrease in mafic minerals compared with previously analyzed strata and a significant proportion of phyllosilicates consistent with this interpretation. These observations suggest that the sediments were predominantly altered in an open system, before or during their emplacement, contrasting with the rock-dominated conditions inferred in sedimentary deposits analyzed at Yellowknife Bay.

Original languageEnglish (US)
Pages (from-to)619-631
Number of pages13
JournalIcarus
Volume321
DOIs
StatePublished - Mar 15 2019

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Mangold, N., Dehouck, E., Fedo, C., Forni, O., Achilles, C., Bristow, T., Downs, R. T., Frydenvang, J., Gasnault, O., L'Haridon, J., Le Deit, L., Maurice, S., McLennan, S. M., Meslin, P. Y., Morrison, S., Newsom, H. E., Rampe, E., Rapin, W., Rivera-Hernandez, F., ... Wiens, R. C. (2019). Chemical alteration of fine-grained sedimentary rocks at Gale crater. Icarus, 321, 619-631. https://doi.org/10.1016/j.icarus.2018.11.004