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Hydrogen Variability in the Murray Formation, Gale Crater, Mars

Thomas, N. H. and Ehlmann, B. L. and Rapin, W. and Rivera-Hernandez, F. and Stein, N. T. and Frydenvang, J. and Gabriel, T. and Meslin, P.-Y. and Maurice, S. and Wiens, R. C. (2020) Hydrogen Variability in the Murray Formation, Gale Crater, Mars. Journal of Geophysical Research. Planets . ISSN 2169-9097. (In Press)

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The Mars Science Laboratory (MSL) Curiosity rover is exploring the Murray formation, a sequence of heterolithic mudstones and sandstones recording fluvial deltaic and lake deposits that comprise over 350 meters of sedimentary strata within Gale crater. We examine >4500 Murray formation bedrock points, employing recent laboratory calibrations for ChemCam laser‐induced breakdown spectroscopy H measurements at millimeter scale. Bedrock in the Murray formation has an interquartile range of 2.3‐3.1 wt. % H₂O, similar to measurements using the DAN and SAM instruments. However, specific stratigraphic intervals include high H targets (6‐18 wt. % H₂O) correlated with Si, Mg, Ca, Mn, or Fe, indicating units with opal, hydrated Mg‐sulfates, hydrated Ca‐sulfates, Mn‐enriched units, and akageneite or other iron oxyhydroxides, respectively. One stratigraphic interval with higher hydrogen is the Sutton Island unit and Blunts Point unit contact, where higher hydrogen is associated with Fe‐rich, Ca‐rich, and Mg‐rich points. A second interval with higher hydrogen occurs in the Vera Rubin ridge portion of the Murray formation, where higher hydrogen is associated with Fe‐rich, Ca‐rich, and Si‐rich points. We also observe trends in the H signal with grain size, separate from chemical variation, whereby coarser‐grained rocks have higher hydrogen. Variability in the hydrogen content of rocks points to a history of water‐rock interaction at Gale crater that included changes in lake water chemistry during Murray formation deposition and multiple subsequent groundwater episodes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Thomas, N. H.0000-0003-1989-4860
Ehlmann, B. L.0000-0002-2745-3240
Rapin, W.0000-0003-4660-8006
Rivera-Hernandez, F.0000-0003-1401-2259
Stein, N. T.0000-0003-3385-9957
Frydenvang, J.0000-0001-9294-1227
Gabriel, T.0000-0002-9767-4153
Meslin, P.-Y.0000-0002-0703-3951
Wiens, R. C.0000-0002-3409-7344
Additional Information:© 2020 American Geophysical Union. Accepted manuscript online: 13 April 2020; Manuscript accepted: 09 March 2020; Manuscript revised: 04 March 2020; Manuscript received: 22 November 2019. Work at Caltech was supported by a NASA MSL Participating Scientist Program grant to B. L. Ehlmann and a National Science Foundation Graduate Research Fellowship grant no. DGE-1144469 to N. H. Thomas. N. H. Thomas thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, the Brinson Foundation, and the Moore Foundation; her participation in the program has benefited this work. Supporting laboratory data have been previously published in Thomas et al. (2018). ChemCam data used for this paper, including major oxide compositions, are publicly available on the Planetary Data System ( Data table containing the measured H (normalized H peak area to O 778 nm) for every ChemCam Murray formation bedrock observation point is publicly available as a Caltech data record (DOI: 10.22002/D1.1349). Gini index mean scores used in this paper are publicly available at Zenodo (DOI: 10.5281/zenodo.3605603).
Group:Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Large Synoptic Survey Telescope CorporationUNSPECIFIED
Brinson FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Mars Science Laboratory Curiosity rover; hydrogen; aqueous geochemistry
Record Number:CaltechAUTHORS:20200413-122616757
Persistent URL:
Official Citation:Thomas, N. H., Ehlmann, B. L., Rapin, W., Rivera‐Hernández, F., Stein, N. T., Frydenvang, J., et al (2020). Hydrogen Variability in the Murray Formation, Gale Crater, Mars. Journal of Geophysical Research: Planets, 125, e2019JE006289.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102507
Deposited By: Tony Diaz
Deposited On:13 Apr 2020 19:34
Last Modified:13 Apr 2020 19:34

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