Hydrogen Variability in the Murray Formation, Gale Crater, Mars
Abstract
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 m of sedimentary strata within Gale crater. We examine >4,500 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 Dynamic Albedo of Neutrons and Sample Analysis at Mars 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.
Additional Information
© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Issue Online: 27 August 2020; Version of Record online: 27 August 2020; 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 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 (http://pds‐geosciences.wustl.edu/missions/msl/chemcam.htm). 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 (https://doi.org/10.22002/D1.1349). Gini index mean scores used in this paper are publicly available at Zenodo (https://doi.org/10.5281/zenodo.3605603).Additional details
- Eprint ID
- 102507
- Resolver ID
- CaltechAUTHORS:20200413-122616757
- NASA
- DGE-1144469
- NSF Graduate Research Fellowship
- Large Synoptic Survey Telescope Corporation
- OAC-1829740
- NSF
- Brinson Foundation
- Gordon and Betty Moore Foundation
- Created
-
2020-04-13Created from EPrint's datestamp field
- Updated
-
2023-06-01Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences