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Title: Basalt-trachybasalt samples in Gale Crater, Mars

The ChemCam instrument on the Mars Science Laboratory (MSL) rover, Curiosity, observed numerous igneous float rocks and conglomerate clasts, reported previously. A new statistical analysis of single-laser-shot spectra of igneous targets observed by ChemCam shows a strong peak at ~55 wt% SiO 2 and 6 wt% total alkalis, with a minor secondary maximum at 47–51 wt% SiO 2 and lower alkali content. The centers of these distributions, together with the rock textures, indicate that many of the ChemCam igneous targets are trachybasalts, Mg# = 27 but with a secondary concentration of basaltic material, with a focus of compositions around Mg# = 54. We suggest that all of these igneous rocks resulted from low-pressure, olivine-dominated fractionation of Adirondack (MER) class-type basalt compositions. This magmatism has subalkaline, tholeiitic affinities. The similarity of the basalt endmember to much of the Gale sediment compositions in the first 1000 sols of the MSL mission suggests that this type of Fe-rich, relatively low-Mg#, olivine tholeiite is the dominant constituent of the Gale catchment that is the source material for the fine-grained sediments in Gale. The similarity to many Gusev igneous compositions suggests that it is a major constituent of ancient Martian magmas, and distinct from themore » shergottite parental melts thought to be associated with Tharsis and the Northern Lowlands. Finally, the Gale Crater catchment sampled a mixture of this tholeiitic basalt along with alkaline igneous material, together giving some analogies to terrestrial intraplate magmatic provinces.« less
 [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [5] ; ORCiD logo [6] ; ORCiD logo [2] ;  [7] ;  [8] ;  [9] ;  [1]
  1. Univ. of Leicester (United Kingdom). Leicester Inst. for Space and Earth Observation, Dept. of Physics and Astronomy
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. U.S. Geological Survey, Flagstaff, AZ (United States). Astrogeology Science Center
  4. Mount Holyoke College, South Hadley, MA (United States). Mineral Spectroscopy Lab.
  5. Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences
  6. Univ. of New Brunswick, Fredericton NB (Canada). Planetary and Space Science Centre
  7. Southern Illinois Univ., Carbondale, IL (United States). Geology Dept.
  8. Open Univ., Milton Keynes (United Kingdom). Dept. of Environment, Earth and Ecosystems
  9. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
Publication Date:
Report Number(s):
Journal ID: ISSN 1086-9379; TRN: US1800404
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Meteoritics and Planetary Science
Additional Journal Information:
Journal Volume: 52; Journal Issue: 11; Journal ID: ISSN 1086-9379
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
National Aeronautic and Space Administration (NASA); USDOE; UKSA
Country of Publication:
United States
58 GEOSCIENCES; Planetary Sciences
OSTI Identifier: