Clay mineral formation under oxidized conditions and implications for paleoenvironments and organic preservation on Mars

Creators: Gainey, Seth R.; Hausrath, Elisabeth M.; Adcock, Christopher T.; Tschauner, Oliver; Hurowitz, Joel A.; Ehlmann, Bethany L.; Xiao, Yuming; Bartlett, Courtney L.

Abstract

Clay mineral-bearing locations have been targeted for martian exploration as potentially habitable environments and as possible repositories for the preservation of organic matter. Although organic matter has been detected at Gale Crater, Mars, its concentrations are lower than expected from meteoritic and indigenous igneous and hydrothermal reduced carbon. We conducted synthesis experiments motivated by the hypothesis that some clay mineral formation may have occurred under oxidized conditions conducive to the destruction of organics. Previous work has suggested that anoxic and/or reducing conditions are needed to synthesize the Fe-rich clay mineral nontronite at low temperatures. In contrast, our experiments demonstrated the rapid formation of Fe-rich clay minerals of variable crystallinity from aqueous Fe^(3+) with small amounts of aqueous Mg^(2+). Our results suggest that Fe-rich clay minerals such as nontronite can form rapidly under oxidized conditions, which could help explain low concentrations of organics within some smectite-containing rocks or sediments on Mars.

Additional Information

© 2017 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received: 31 July 2015; Accepted: 01 September 2017; Published online: 01 November 2017. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. NNX10AN23H issued through the NASA Training Grant: National Space Grant College and Fellowship Program (Space Grant) and the Mars Fundamental Research Program Grant No. NNX12AH96G. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operation is supported by DOE-NNSA under Award No. DE-NA0001974, with partial instrumentation funding by NSF. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Part of this work was conducted at beamline 12.2.2, Advanced Light Source (ALS). ALS is a DOE Office of Science User Facility under contract no. DE.AC02-05CH11231. Y.X. acknowledges the support of DOE-BES/DMSE under Award DE-FG02-99ER45775. O.T. acknowledges support through DOE Cooperative Agreement #DE-NA0001982 and DESC0005278. We also thank the University of Nevada, Las Vegas's Graduate and Professional Student Association. The authors thank Michael Steiner, Valerie Tu, Renee Schofield and Angela Garcia for contributions and help in the development of this manuscript. We also thank Minghua Ren for aid in Microprobe analysis and George Rossman, Cedric Pilorget, Jennifer Buz, Michael Thorpe and Lulu Pan for aid in the collection of spectra. Data availability: The authors declare that the data supporting the finding of this study are available within the paper and its supplementary materials, and/or from the corresponding author S.R.G. upon reasonable request. Contributions: S.R.G., E.M.H. and J.A.H.: Conceived the project. S.R.G.: Performed the experimental syntheses, and S.R.G., E.M.H., J.A.H., B.L.E., O.T., C.T.A., Y.X. and C.L.B.: Contributed to the collection and interpretation of analyses of synthesized materials. All authors have contributed to the writing of the manuscript. The authors declare no competing financial interests.

Attached Files

Published - 41467_2017_Article_1235.pdf

Supplemental Material - 41467_2017_1235_MOESM1_ESM.pdf

Files

41467_2017_1235_MOESM1_ESM.pdf

Files (5.5 MB)

Name	Size	Download all
41467_2017_1235_MOESM1_ESM.pdf md5:a6636f7cd1ce529520a6c511c61c052f	3.5 MB	Preview Download
41467_2017_Article_1235.pdf md5:30d2ccb4fc0226ffb215ddf1d59b227a	2.0 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes