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Shock metamorphism of clay minerals on Mars by meteor impact
Author(s) -
Michalski Joseph R.,
Glotch Timothy D.,
Friedlander Lonia R.,
Darby Dyar M.,
Bish David L.,
Sharp Thomas G.,
Carter John
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl073423
Subject(s) - shock metamorphism , mars exploration program , clay minerals , geology , martian , kaolinite , mineralogy , meteor (satellite) , infrared , meteorite , ejecta , shock (circulatory) , geochemistry , atmosphere of mars , mineral , ferrous , astrobiology , materials science , astrophysics , medicine , physics , optics , metallurgy , supernova , meteorology
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.