Title: Composition of conglomerates analyzed by the Curiosity rover: Implications for Gale Crater crust and sediment sources

Abstract

The Curiosity rover has analyzed various detrital sedimentary rocks at Gale Crater, among which fluvial and lacustrine rocks are predominant. Conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration, enabling us to link their chemistry to that of source rocks on the Gale Crater rims. Here, we report the results of six conglomerate targets analyzed by Alpha-Particle X-ray Spectrometer and 40 analyzed by ChemCam. The bulk chemistry derived by both instruments suggests two distinct end-members for the conglomerate compositions. The first group (Darwin type) is typical of conglomerates analyzed before sol 540; it has a felsic alkali-rich composition, with a Na₂O/K₂O > 5. The second group (Kimberley type) is typical of conglomerates analyzed between sols 540 and 670 in the vicinity of the Kimberley waypoint; it has an alkali-rich potassic composition with Na₂O/K₂O < 2. The variety of chemistry and igneous textures (when identifiable) of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks. Conglomerate compositions are in agreement with most of the felsic alkali-rich float rock compositions analyzed in the hummocky plains. The average composition of conglomerates can be taken as a proxy of the average igneous crustmore » composition at Gale Crater. Finally, the differences between the composition of conglomerates and that of finer-grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes (especially for Mg enrichments in fine-grained rocks), physical sorting, and mixing with finer-grained material of different composition.« less

Authors:

Mangold, N. ^[1]; Thompson, L. M. ^[2]; Forni, O. ^[3]; Williams, A. J. ^[4]; Fabre, C. ^[5]; Le Deit, L. ^[1]; Wiens, R. C.  ^[6];

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

Williams, R. ^[7]; Anderson, R. B. ^[8]; Blaney, D. L. ^[9]; Calef, F. ^[9]; Cousin, A. ^[3]; Clegg, S. M.  ^[6];

• Search DOE PAGES for author "Clegg, S. M."
• Search DOE PAGES for ORCID "0000-0002-0338-0948"

Dromart, G. ^[10]; Dietrich, W. E. ^[11]; Edgett, K. S. ^[12]; Fisk, M. R. ^[13]; Gasnault, O. ^[3]; Gellert, R. ^[14]; Grotzinger, J. P. ^[15] more »; Kah, L. ^[16]; Le Mouélic, S. ^[1]; McLennan, S. M. ^[17]; Maurice, S. ^[3]; Meslin, P. -Y. ^[3]; Newsom, H. E. ^[18]; Palucis, M. C. ^[11]; Rapin, W. ^[3]; Sautter, V. ^[19]; Siebach, K. L. ^[15]; Stack, K. ^[9]; Sumner, D. ^[20]; Yingst, A. ^[21] « less

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+ Show Author Affiliations

1. Univ. of Nantes (France). National Centre for Scientific Research (CNRS), Lab. of Planetology and Geodynamics
2. Univ. of New Brunswick, Fredericton NB (Canada). Planetary and Space Science Centre, Dept. of Earth Sciences
3. Univ. of Toulouse (France). National Centre for Scientific Research (CNRS). Inst. for Research in Astrophysics and Planetology
4. Towson Univ., MD (United States). Dept. of Physics, Astronomy, and Geosciences
5. Univ. of Lorraine, Nancy (France). GeoRessources
6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
7. Planetary Science Inst., Tucson Arizona (United States)
8. U.S. Geological Survey, Flagstaff, AZ (United States)
9. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
10. Univ. of Lyon (France). Lyon Geology Lab.
11. Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science
12. Malin Space Science Systems, San Diego, CA (United States)
13. Oregon State Univ., Corvallis, OR (United States). Colege of Earth, Ocean and Atmospheric Sciences
14. Univ. of Guelph, ON (Canada). Dept. of Physics
15. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Geological and Planetary Sciences
16. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Earth and Planetary Sciences
17. State Univ. of New York (SUNY), Stony Brook, NY (United States). Dept. of Geosciences
18. Inst. of Meteoritics, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences
19. Museum National d'Histoire Naturelle de Paris, (France). Inst. of Mineralogy, Materials Physics and Cosmochemistry
20. Univ. of California, Davis, CA (United States). Dept. of Earth and Planetary Sciences
21. Planetary Science Inst., Tucson, AZ (United States)

Publication Date:

Wed Mar 16 00:00:00 EDT 2016

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA)

OSTI Identifier:

1417818

Report Number(s):

LA-UR-17-27711
Journal ID: ISSN 2169-9097

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Planets

Additional Journal Information:

Journal Volume: 121; Journal Issue: 3; Journal ID: ISSN 2169-9097

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Planetary Sciences