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Title: Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars

The Curiosity rover's campaign at Pahrump Hills provides the first analyses of lower Mount Sharp strata. We report ChemCam elemental composition of a diverse assemblage of post-depositional features embedded in, or cross-cutting, the host rock. ChemCam results demonstrate their compositional diversity, especially compared to the surrounding host rock: (i) Dendritic aggregates and relief enhanced features, characterized by a magnesium enhancement and sulfur detection, and interpreted as Mg-sulfates; (ii) A localized observation that displays iron enrichment associated with sulfur, interpreted as Fe-sulfate; (iii) Dark raised ridges with varying Mg- and Ca-enriched compositions compared to host rock; (iv) Several dark-toned veins with calcium enhancement associated with fluorine detection, interpreted as fluorite veins. (v) Light-toned veins with enhanced calcium associated with sulfur detection, and interpreted as Ca-sulfates. The diversity of the Pahrump Hills diagenetic assemblage suggests a complex post-depositional history for fine-grained sediments for which the origin has been interpreted as fluvial and lacustrine. Assessment of the spatial and relative temporal distribution of these features shows that the Mg-sulfate features are predominant in the lower part of the section, suggesting local modification of the sediments by early diagenetic fluids. Conversely, light-toned Ca-sulfate veins occur in the whole section and cross-cut all other features.more » A relatively late stage shift in geochemical conditions could explain this observation. The Pahrump Hills diagenetic features have no equivalent compared to targets analyzed in other locations at Gale crater. Only the light-toned Ca-sulfate veins are present elsewhere, along Curiosity's path, suggesting they formed through a common late-stage process that occurred at over a broad area.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [3] ;  [2] ; ORCiD logo [4] ;  [5] ;  [6] ;  [7] ;  [6] ; ORCiD logo [4] ;  [8] ;  [9] ;  [2] ;  [10] ;  [3] ; ORCiD logo [4] ;  [2] ;  [1] ;  [1] more »;  [2] ;  [2] ;  [11] ;  [8] ;  [2] ;  [12] ;  [6] ;  [13] « less
  1. Univ. of Nantes (France). Lab. of Planetology and Geodynamics
  2. Univ. of Toulouse (France). Center for Space Studies of Radiation
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Earth and Planetary Sciences
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  5. U.S. Geological Survey Astrogeology Science Center, Flagstaff, AZ (United States)
  6. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  7. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
  8. Univ. of Lorraine, Nancy (France). Geo Ressources
  9. Oregon State Univ., Corvallis, OR (United States). College of Earth Ocean and Atmospheric Sciences
  10. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Geologic and Planetary Sciences
  11. NASA Johnson Space Center, Houston, TX (United States). Astromaterials Research and Exploration Science Division
  12. Univ. of Toulouse (France). Center for Space Studies of Radiation; German Aerospace Center (DLR), Berlin (Germany)
  13. Univ. of California, Davis, CA (United States). Earth and Planetary Sciences
Publication Date:
Report Number(s):
LA-UR-17-27694
Journal ID: ISSN 0019-1035
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Icarus
Additional Journal Information:
Journal Volume: 281; Journal Issue: C; Journal ID: ISSN 0019-1035
Publisher:
Elsevier
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; Mars surface; Geological processes; Mineralogy
OSTI Identifier:
1412864