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Nanoscale Analyses of X-ray Amorphous Material from Terrestrial Ultramafic Soils Record Signatures of Environmental Conditions Useful for Interpreting Past Martian Conditions
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  • Anthony David Feldman,
  • Elisabeth M. Hausrath,
  • Elizabeth B. Rampe,
  • Thomas G. Sharp,
  • Oliver Tschauner,
  • Antonio Lanzirotti,
  • Matthew Newville
Anthony David Feldman
Desert Research Institute

Corresponding Author:anthony.feldman@dri.edu

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Elisabeth M. Hausrath
University of Nevada, Las Vegas
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Elizabeth B. Rampe
NASA Johnson Space Center
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Thomas G. Sharp
Arizona State University
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Oliver Tschauner
University of Nevada
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Antonio Lanzirotti
Argonne National Laboratory (DOE)
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Matthew Newville
University of Chicago
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X-ray amorphous material that is variably Mg/Fe/Si-rich and Al-poor and that likely contains secondary alteration products is prevalent in Gale crater sediments and rocks (15-73 wt.%). However, the structure and origin of these materials and their implications for past environmental conditions remain unknown. In this study, we use transmission electron microscopy and synchrotron microprobe analyses to examine Mg/Fe/Si-rich and Al-poor ultramafic soils from the warm Mediterranean climate Klamath Mountains of California and cold subarctic climate Tablelands of Newfoundland, Canada to help interpret environmental conditions during the formation of chemically similar X-ray amorphous material in Gale crater, Mars. Primary glass is absent from the Klamath Mountains and Tablelands materials; secondary X-ray amorphous material includes globular amorphous silica and chemically heterogeneous nanospherical amorphous material and nanocrystalline phases. Globular amorphous silica is only present in soils that undergo extensive periods of cyclic freezing. Fe-containing X-ray amorphous material from the subarctic Tablelands is significantly richer in Mg and Si than X-ray amorphous material from the warmer Klamath Mountains. Fe-rich nanocrystallites contain more Mg and Si in the subarctic Tablelands but are more highly Fe-enriched in the warmer Klamath Mountains. Potential secondary nanocrystalline phyllosilicates are only observed in the warmest examined soil in the Klamath Mountains. These characteristics – the presence or absence of amorphous silica, the chemical composition of X-ray amorphous material, the abundance and composition of Fe-rich nanocrystallites, and the presence or absence of secondary phyllosilicates - provide helpful identifiers to interpret past environmental conditions during the formation of X-ray amorphous material on Mars.
06 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive