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

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 Na 2O/K 2O > 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 Na 2O/K 2O < 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 ofmore » the average igneous crust 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:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ; ORCiD logo [6] ;  [7] ;  [8] ;  [9] ;  [9] ;  [3] ; ORCiD logo [6] ;  [10] ;  [11] ;  [12] ;  [13] ;  [3] ;  [14] ;  [15] more »;  [16] ;  [1] ;  [17] ;  [3] ;  [3] ;  [18] ;  [11] ;  [3] ;  [19] ;  [15] ;  [9] ;  [20] ;  [21] « less
  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:
Report Number(s):
LA-UR-17-27711
Journal ID: ISSN 2169-9097
Grant/Contract Number:
AC52-06NA25396
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
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
National Aeronautics and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Planetary Sciences
OSTI Identifier:
1417818