Redox stratification of an ancient lake in Gale crater, Mars

Creators: Hurowitz, J. A.; Grotzinger, J. P.; Fischer, W. W.; McLennan, S. M.; Milliken, R. E.; Stein, N.; Vasavada, A. R.; Blake, D. F.; Dehouck, E.; Eigenbrode, J. L.; Fairén, A. G.; Frydenvang, J.; Gellert, R.; Grant, J. A.; Gupta, S.; Herkenhoff, K. E.; Ming, D. W.; Rampe, E. B.; Schmidt, M. E.; Siebach, K. L.; Stack-Morgan, K.; Sumner, D. Y.; Wiens, R. C.

Abstract

In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized.

Additional Information

© 2017 American Association for the Advancement of Science. Received 31 July 2016; accepted 19 April 2017. We are indebted to the MSL project's engineering and management teams for their efforts in making the mission effective and enhancing science operations. We are also grateful to those MSL team members who participated in tactical and strategic operations, without whom the data presented here could not have been collected. J.A.H. acknowledges support from a subcontract from the NASA Jet Propulsion Laboratory, California Institute of Technology. J.P.G. acknowledges the support of the NASA Astrobiology Institute. A.G.F. was supported by the Project "icyMARS," European Research Council Starting Grant no. 307496. J.F. acknowledges the support from the Villum Foundation. R.G. and M.E.S. acknowledge support from the Canadian Space Agency, which is responsible for funding the APXS instrument and its operations. Data presented in this paper are archived in the Planetary Data System at http://pds-geosciences.wustl.edu/missions/msl/index.htm. Three anonymous reviewers are acknowledged for their contributions.

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