Shock metamorphism of clay minerals on Mars by meteor impact

Joseph R. Michalski, Timothy D. Glotch, Lonia R. Friedlander, M. Darby Dyar, David L. Bish, Thomas G. Sharp, John Carter

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


A large fraction of clay minerals detected on Mars by infrared remote sensing represent materials exhumed from the subsurface by meteor impact, begging the question of whether the infrared features used to detect the clays are affected by shock associated with the impacts. We used X-ray diffraction and infrared and Mössbauer spectroscopy to evaluate the mineralogy of five clay minerals after experimentally shocking them to six shock pressures from ~10 to 40 GPa. The shocked clays exhibit three main relevant shock effects: (1) an overall decrease in infrared spectral contrast in the impact-fragmented materials, (2) oxidation of Fe in ferrous clays, and (3) loss of some spectral structure in relatively well-ordered clays such as kaolinite. Other than the widespread oxidation of ferrous clays, shock metamorphism likely has little effect on the accurate interpretation of clay mineralogy on Mars from remote sensing data. However, we are able to identify rare cases of extreme shock in some Martian clay deposits.

Original languageEnglish
Pages (from-to)6562-6569
Number of pages8
JournalGeophysical Research Letters
Issue number13
StatePublished - 16 Jul 2017


  • Mars
  • astrobiology
  • clay minerals
  • infrared
  • meteor impact
  • mineralogy

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences (all)


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