Title: Chemical alteration of fine-grained sedimentary rocks at Gale crater

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. Furthermore, 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.

Authors:

Mangold, Nicolas ^[1]; Dehouck, E.  ^[2];

• Search DOE PAGES for author "Dehouck, E."
• Search DOE PAGES for ORCID "0000-0002-1368-4494"

Fedo, C. ^[3]; Forni, O.  ^[4];

• Search DOE PAGES for author "Forni, O."
• Search DOE PAGES for ORCID "0000-0001-6772-9689"

Achilles, C. ^[5]; Bristow, T. ^[6]; Downs, R. T.  ^[5];

• Search DOE PAGES for author "Downs, R. T."
• Search DOE PAGES for ORCID "0000-0002-8380-7728"

Frydenvang, J.  ^[7];

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• Search DOE PAGES for ORCID "0000-0001-9294-1227"

Gasnault, O.  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-6979-9012"

L'Haridon, J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9323-1603"

Deit, L. Le ^[1]; Maurice, S. ^[4]; McLennan, S. M. ^[8]; Meslin, P. -Y. ^[4]; Morrison, S.  ^[5];

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• Search DOE PAGES for ORCID "0000-0002-1712-8057"

Newsom, H. E.  ^[9];

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• Search DOE PAGES for ORCID "0000-0002-4358-8161"

Rampe, E. ^[10]; Rapin, W. ^[11]; Rivera-Hernandez, F.  ^[12];

• Search DOE PAGES for author "Rivera-Hernandez, F."
• Search DOE PAGES for ORCID "0000-0003-1401-2259"

Salvatore, M. ^[13] more »; Wiens, R. C.  ^[14]

• Search DOE PAGES for author "Wiens, R. C."
• Search DOE PAGES for ORCID "0000-0002-3409-7344"

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+ Show Author Affiliations

1. Univ. de Nantes, Univ. d'Angers, Nantes (France)
2. Univ. Claude Bernard (France)
3. Univ. of Tennessee, Knoxville, TN (United States)
4. Univ. de Toulouse, Toulouse (France)
5. Univ. of Arizona, Tucson, AZ (United States)
6. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
7. Univ. of Copenhagen (Denmark)
8. Stony Brook Univ., Stony Brook, NY (United States)
9. Univ. of New Mexico, Albuquerque, NM (United States)
10. Aerodyne Industries, Houston, TX (United States)
11. UC Davis Earth and Planetary Science, Davis, CA (United States)
12. California Inst. of Technology (CalTech), Pasadena, CA (United States)
13. Northern Arizona Univ., Flagstaff, AZ (United States)
14. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Sat Nov 17 00:00:00 EST 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA); USDOE

OSTI Identifier:

1483549

Report Number(s):

LA-UR-18-29015
Journal ID: ISSN 0019-1035

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Icarus

Additional Journal Information:

Journal Volume: 321; Journal ID: ISSN 0019-1035

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Planetary Sciences