Elemental Geochemistry of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars

Creators: McLennan, S. M.; Anderson, R. B.; Bell, J. F., III; Bridges, J. C.; Calef, F.; Campbell, John L.; Clark, B. C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D. J.; Dromart, G.; Dyar, M. D.; Edgar, L. A.; Ehlmann, B. L.; Fabre, C.; Forni, O.; Gasnault, O.; Gellert, R.; Gordon, S.; Grant, A.; Grotzinger, J. P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J. A.; King, P. L.; Le Mouélic, S.; Leshin, L. A.; Léveillé, R.; Lewis, K. W.; Mangold, N.; Maurice, S.; Ming, D. W.; Morris, R. V.; Nachon, M.; Newsom, H. E.; Ollila, A.; Perrett, G. M.; Rice, M. S.; Schmidt, M. E.; Schwenzer, S. P.; Stack, K.; Stolper, E. M.; Sumner, D. Y.; Treiman, A. H.; VanBommel, S.; Vaniman, D. T.; Vasavada, A.; Wiens, R. C.; Yingst, R. A.; MSL Science Team

Abstract

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from approximately average Martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved indicating arid, possibly cold, paleoclimates and rapid erosion/deposition. Absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low temperature, circum-neutral pH, rock-dominated aqueous conditions. High spatial resolution analyses of diagenetic features, including concretions, raised ridges and fractures, indicate they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components and hydrated calcium-sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. Geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

Additional Information

Copyright 2013 American Association for the Advancement of Science. Submitted Manuscript: 30 October 2013. Received for publication 15 August 2013. Accepted for publication 12 November 2013. Published Online December 9 2013. Much of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Development and operation of the ChemCam and APXS instruments were also supported by funds from the French Space Agency, CNES and the Canadian Space Agency. Organizations supporting research include NASA, the Canadian Space Agency and NSERC (Canada) and the United Kingdom Space Agency (UK). Chemical data presented here are derived from archived data sets in the NASA Planetary Data System (PDS) http://pds-geosciences.wustl.edu/missions/msl/. We are grateful to the MSL engineering and management teams for making the mission and this scientific investigation possible and to science team members who contributed to mission operations. The senior author (SMM) thanks Lamont-Doherty Earth Observatory of Columbia University, and especially Sidney Hemming, for hospitality during a sabbatical when the manuscript was being prepared.

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