Hydrous olivine alteration on Mars and Earth

1,2Zoltán Váci,1Carl B. Agee,2Christopher D. K. Herd,2,3Erin Walton,4Oliver Tschauner,1Karen Ziegler,5Vitali B. Prakapenka,5Eran Greenberg,4Sylvia Monique‐Thomas
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13479]
1Department of Earth and Planetary Sciences, Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, 87106 USA
2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3 Canada
3Department of Earth and Planetary Sciences, MacEwan University, Edmonton, Alberta, T5J 4S2 Canada
4Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, Nevada, 89154 USA
5GSECARS, Argonne National Laboratory, Lemont, Illinois, 60439 USA
Published by arrangement with John Wiley & Sons

Hydrous alteration of olivine macrocrysts in a Martian olivine phyric basalt, NWA 10416, and a terrestrial basalt from southern Colorado are examined using SEM, EPMA, TEM, and µXRD techniques. The olivines in the meteorite contain linear nanotubes of hydrous material, amorphous areas, and fluid dissolution textures quite distinct from alteration identified in other Martian meteorites. Instead, they bear resemblance to terrestrial deuteric alteration features. The presence of the hydrous alteration phase Mg‐laihunite within the olivines has been confirmed by µXRD analysis. The cores of the olivines in both Martian and terrestrial samples are overgrown by unaltered rims whose compositions match those of a separate population of groundmass olivines, suggesting that the core olivines are xenocrysts whose alteration preceded crystallization of the groundmass. The terrestrial sample is linked to deep crustal metasomatism and the “ignimbrite flare‐up” of the Oligocene epoch. The comparison of the two samples suggests the existence of an analogous relatively water‐rich magmatic reservoir on Mars.

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