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Grain Size Variations in the Murray Formation: Stratigraphic Evidence for Changing Depositional Environments in Gale Crater, Mars

Rivera‐Hernández, Frances and Sumner, Dawn Y. and Mangold, Nicolas and Banham, Steven G. and Edgett, Kenneth S. and Fedo, Christopher M. and Gupta, Sanjeev and Gwizd, Samantha and Heydari, Ezat and Maurice, Sylvestre and Nachon, Marion and Newsom, Horton and Schieber, Juergen and Stack‐Morgan, Katie and Stein, Nathan and Wiens, Roger C. (2020) Grain Size Variations in the Murray Formation: Stratigraphic Evidence for Changing Depositional Environments in Gale Crater, Mars. Journal of Geophysical Research. Planets, 125 (2). Art. No. e2019JE006230. ISSN 2169-9097. https://resolver.caltech.edu/CaltechAUTHORS:20200227-090615391

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Abstract

The lowermost exposure of the Murray formation in Gale crater, Mars, was interpreted as sediment deposited in an ancient lake based on data collected by the Curiosity rover. Constraining the stratigraphic extent and duration of this environment has important implications for the paleohydrology of Gale. Insights into early Martian environments and paleofluid flow velocity can be obtained from grain size in rocks. Visual inspection of grain size is not always available for rocks investigated at field sites on Mars due to limited image coverage. But grain sizes can also be estimated from the Gini Index Mean Score, a grain‐size proxy that uses point‐to‐point chemical variations in ChemCam Laser Induced Breakdown Spectroscopy data. New Gini Index Mean Score results indicate that the Murray formation is dominated by mudstones with grains smaller than the spatial resolution of all rover cameras. Intervals of fine to coarse sandstone also are present, some of which are verified using observations of grain size and sedimentary structures in associated images. Overall, results demonstrate that most of the Murray consists of mudstone, suggesting settling of grains from suspension in low energy depositional environments such as lakes. Some of the mudstones contain desiccation cracks indicating periods of drying with a lowering of lake water level. However, beds and lenses of cross‐bedded sandstones are common at specific intervals, suggesting episodes of fluvial and possibly eolian deposition. The persistence of lacustrine deposits interspersed with fluvial deposits suggests that liquid water was sustained on the Martian surface for tens of thousands to millions of years.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019je006230DOIArticle
https://doi.org/10.5281/zenodo.3605603DOIData
ORCID:
AuthorORCID
Rivera‐Hernández, Frances0000-0003-1401-2259
Sumner, Dawn Y.0000-0002-7343-2061
Mangold, Nicolas0000-0002-0022-0631
Banham, Steven G.0000-0003-1206-1639
Edgett, Kenneth S.0000-0001-7197-5751
Fedo, Christopher M.0000-0002-2626-1132
Nachon, Marion0000-0003-0417-7076
Newsom, Horton0000-0002-4358-8161
Stein, Nathan0000-0003-3385-9957
Wiens, Roger C.0000-0002-3409-7344
Additional Information:© 2020 American Geophysical Union. Received 1 OCT 2019; Accepted 14 JAN 2020. This research was funded by the Chateaubriand Science, Technology, Engineering, and Mathematics Fellowship sponsored by the Embassy of France in the United States, and by the Mars Science Laboratory Project through the NASA Mars Exploration Program. Collaborators in France who contributed to this research were funded by the Centre National d'Etudes Spatiales. We would like to thank the rest of the MSL Sedimentology and Stratigraphy working group, and the MAHLI and ChemCam instrument teams for constructive conversations and their fabulous datasets. All of the ChemCam LIBS data used in this manuscript can be found in Table S2 and freely online, along with their corresponding RMI images, through the Planetary Data System Geosciences node (https://pds‐geosciences.wustl.edu/missions/msl/chemcam.htm). All of the MAHLI and Mastcam images used in this manuscript are freely available through the Planetary Data System Cartography and Imaging Sciences node (https://pds‐imaging.jpl.nasa.gov/volumes/msl.html). All GIMS results for the Murray formation from Sols 750–1804 can be found in Table S3, Table S4, and archived online (https://doi.org/10.5281/zenodo.3605603).
Funders:
Funding AgencyGrant Number
Chateaubriand Science, Technology, Engineering, and Mathematics FellowshipUNSPECIFIED
Embassy of FranceUNSPECIFIED
NASAUNSPECIFIED
Centre National d'Etudes Spatiales (CNES)UNSPECIFIED
Subject Keywords:Mars; grain size; Mars Science Laboratory; sedimentary rocks; lakes; LIBS
Issue or Number:2
Record Number:CaltechAUTHORS:20200227-090615391
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200227-090615391
Official Citation:Rivera‐Hernández, F., Sumner, D. Y., Mangold, N., Banham, S. G., Edgett, K. S., Fedo, C. M., et al (2020). Grain Size Variations in the Murray Formation: Stratigraphic Evidence for Changing Depositional Environments in Gale Crater, Mars. Journal of Geophysical Research: Planets, 125, e2019JE006230. https://doi.org/10.1029/2019JE006230
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101604
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Feb 2020 17:19
Last Modified:03 Aug 2020 19:05

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