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Sci Adv. 2018 Jun 6;4(6):eaar3330. doi: 10.1126/sciadv.aar3330. eCollection 2018 Jun.

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

Author information

1
NASA Ames Research Center, Moffett Field, CA 94035, USA.
2
NASA Johnson Space Center, Houston, TX 77058, USA.
3
Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA.
4
Chesapeake Energy, Oklahoma City, OK 73154, USA.
5
Lunar and Planetary Institute, Houston, TX 77058, USA.
6
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
7
Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
8
Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
9
Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
10
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
11
Earth, Atmospheric, and Planetary Sciences Department, Purdue University, West Lafayette, IN 47907, USA.
12
Laboratoire de Planétologie et Géodynamique, UMR6112, CNRS, Université Nantes, Université Angers, Nantes, France.
13
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
14
Planetary Science Institute, Tucson, AZ 85719, USA.

Abstract

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.

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