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An interval of high salinity in ancient Gale crater lake on Mars

Rapin, W. and Ehlmann, B. L. and Dromart, G. and Schieber, J. and Thomas, N. H. and Fischer, W. W. and Fox, V. K. and Stein, N. T. and Nachon, M. and Clark, B. C. and Kah, L. C. and Thompson, L. and Meyer, H. A. and Gabriel, T. S. J. and Hardgrove, C. and Mangold, N. and Rivera-Hernandez, F. and Wiens, R. C. and Vasavada, A. R. (2019) An interval of high salinity in ancient Gale crater lake on Mars. Nature Geoscience, 12 (11). pp. 889-895. ISSN 1752-0894. https://resolver.caltech.edu/CaltechAUTHORS:20190829-094132078

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Abstract

Precipitated minerals, including salts, are primary tracers of atmospheric conditions and water chemistry in lake basins. Ongoing in situ exploration by the Curiosity rover of Hesperian (around 3.3–3.7 Gyr old) sedimentary rocks within Gale crater on Mars has revealed clay-bearing fluvio-lacustrine deposits with sporadic occurrences of sulfate minerals, primarily as late-stage diagenetic veins and concretions. Here we report bulk enrichments, disseminated in the bedrock, of 30–50 wt% calcium sulfate intermittently over about 150 m of stratigraphy, and of 26–36 wt% hydrated magnesium sulfate within a thinner section of strata. We use geochemical analysis, primarily from the ChemCam laser-induced breakdown spectrometer, combined with results from other rover instruments, to characterize the enrichments and their lithology. The deposits are consistent with early diagenetic, pre-compaction salt precipitation from brines concentrated by evaporation, including magnesium sulfate-rich brines from extreme evaporative concentration. This saline interval represents a substantial hydrological perturbation of the lake basin, which may reflect variations in Mars’ obliquity and orbital parameters. Our findings support stepwise changes in Martian climate during the Hesperian, leading to more arid and sulfate-dominated environments as previously inferred from orbital observations.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1038/s41561-019-0458-8DOIArticle
https://rdcu.be/bV7GAPublisherFree ReadCube access
ORCID:
AuthorORCID
Rapin, W.0000-0003-4660-8006
Ehlmann, B. L.0000-0002-2745-3240
Thomas, N. H.0000-0003-1989-4860
Fischer, W. W.0000-0002-8836-3054
Stein, N. T.0000-0003-3385-9957
Nachon, M.0000-0003-0417-7076
Clark, B. C.0000-0002-5546-8757
Kah, L. C.0000-0001-7172-2033
Thompson, L.0000-0002-5444-952X
Gabriel, T. S. J.0000-0002-9767-4153
Hardgrove, C.0000-0002-8556-6630
Mangold, N.0000-0002-0022-0631
Rivera-Hernandez, F.0000-0003-1401-2259
Wiens, R. C.0000-0002-3409-7344
Vasavada, A. R.0000-0003-2665-286X
Additional Information:© 2019 Springer Nature Limited. Received 13 February 2019; Accepted 30 August 2019; Published 07 October 2019. Data availability: All in situ and orbital data used in this study are available in the NASA Planetary Data System (https://pds-geosciences.wustl.edu). Other supplementary data that support the findings of this study are available from the corresponding author on reasonable request. Thanks to the MSL operations team for their dedication in generating this dataset, and to the LANL team for collection of data to support sulfur calibration. Thanks to J. Grotzinger, C. Fedo, K. Siebach, L. Edgar and other members of the informal MSL Sed-Strat group for discussions that helped improve this work. The authors also thank S. Clegg and other members of the ChemCam team for discussions on sulfur signal calibration. W.R. and B.L.E. were funded by a MSL Participating Scientist grant NNN12AA01C. The work of G.D. was supported by the CNES through the ChemCam Program. This work and the MSL project are supported by the NASA Mars Exploration Program. Author Contributions: W.R. analysed the LIBS and image data and conceived and wrote the manuscript. W.R., B.L.E. and G.D. conceived and revised the manuscript. J.S., W.W.F., B.C.C., L.C.K., N.M., R.C.W. and A.R.V., contributed to the interpretation of the data and revisions of the manuscript. N.H.T. provided LIBS chloride peak analyses. V.K.F. analysed CRISM signatures of hydrated sulfates. N.T.S. and F.R.H. provided grain size estimates from Mars Hand Lens Imager (MAHLI) images of Murray bedrock. M.N. and H.A.M. identified and mapped sulfate vein occurrences. L.T. analysed APXS data of Murray bedrock. T.S.J.G. and C.H. provided DAN data analysis. The authors declare no competing interests.
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
NASANNN12AA01C
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Subject Keywords:Geochemistry; Hydrology; Inner planets
Issue or Number:11
Record Number:CaltechAUTHORS:20190829-094132078
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190829-094132078
Official Citation:Rapin, W., Ehlmann, B.L., Dromart, G. et al. An interval of high salinity in ancient Gale crater lake on Mars. Nat. Geosci. 12, 889–895 (2019) doi:10.1038/s41561-019-0458-8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98329
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:07 Oct 2019 17:42
Last Modified:20 Apr 2020 08:47

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