Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars

Thomas Bristow (1) , Elizabeth Rampe (2) , Cherie N Achilles (3) , David F Blake (1) , Steve J Chipera (4) , Patricia Craig (5) , Joy Crisp , David Des Marais (1) , Robert T Downs , Ralf Gellert (6) , John Grotzinger (7) , Sanjeev Gupta (8) , Robert M Hazen , Briony Horgan , Joanna V Hogancamp , Nicolas Mangold (9) , Paul R Mahaffy (10) , Amy C Mcadam (10) , Doug W. Ming (11) , John Michael M Morookian , Richard V Morris , Shaunna M Morrison , Allan H Treiman , David T Vaniman , Ashwin Vasavada (12) , Albert S Yen (12)

1 ARC - NASA Ames Research Center
2 JSC - NASA Johnson Space Center
3 Department of Geosciences [University of Arizona]
4 Chesapeake Energy Corporation
5 Coastal Waters Program
6 Department of Physics [Guelph]
7 Division of Geological and Planetary Sciences [Pasadena]
8 Institute of Cosmology and Gravitation - Institute of Cosmology and Gravitation
9 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
10 GSFC - NASA Goddard Space Flight Center
11 ARES - Astromaterials Research and Exploration Science
12 JPL - Jet Propulsion Laboratory

Clay minerals provide indicators of the evolution of aqueous conditions and possible habitats for life on ancient Mars. Analyses by the Mars Science Laboratory rover Curiosity show that ~3.5–billion year (Ga) fluvio-lacustrine mudstones in Gale crater contain up to ~28 weight % (wt %) clay minerals. We demonstrate that the species of clay minerals deduced from x-ray diffraction and evolved gas analysis show a strong paleoenvironmental dependency. While perennial lake mudstones are characterized by Fe-saponite, we find that stratigraphic intervals associated with episodic lake drying contain Al-rich, Fe3+-bearing dioctahedral smectite, with minor (3 wt %) quantities of ferripyrophyllite, interpreted as wind-blown detritus, found in candidate aeolian deposits. Our results suggest that dioctahedral smectite formed via near-surface chemical weathering driven by fluctuations in lake level and atmospheric infiltration, a process leading to the redistribution of nutrients and potentially influencing the cycling of gases that help regulate climate.

Domaines: Planétologie

Thomas Bristow, Elizabeth Rampe, Cherie N Achilles, David F Blake, Steve J Chipera, et al.. Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars. Science Advances , 2018, 4 (6), pp.eaar3330. ⟨10.1126/sciadv.aar3330⟩. ⟨hal-02344704⟩