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Diagenesis of Vera Rubin ridge, Gale crater, Mars from Mastcam multispectral images
  • +16
  • Briony Heather Noelle Horgan,
  • Jeffrey R. Johnson,
  • Abigail A. Fraeman,
  • Melissa Susanne Rice,
  • Christina Seeger,
  • James F Bell III,
  • Kristen Bennett,
  • Edward Cloutis,
  • Jens Frydenvang,
  • Jonas L'Haridon,
  • Nicolas Mangold,
  • Lauren Ashley Edgar,
  • John P. Grotzinger,
  • Samantha Jacob,
  • Elizabeth B. Rampe,
  • Frances Rivera-Hernández,
  • Vivian Zheng Sun,
  • Lucy M Thompson,
  • Danika Wellington
Briony Heather Noelle Horgan
Purdue University, Purdue University

Corresponding Author:[email protected]

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Jeffrey R. Johnson
Johns Hopkins University Applied Physics Laboratory, Johns Hopkins University Applied Physics Laboratory
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Abigail A. Fraeman
Jet Propulsion Laboratory, California Institute of Technology, Jet Propulsion Laboratory, California Institute of Technology
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Melissa Susanne Rice
Western Washington University, Western Washington University
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Christina Seeger
Western Washington University, Western Washington University
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James F Bell III
Arizona State University, Arizona State University
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Kristen Bennett
USGS Flagstaff, USGS Flagstaff
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Edward Cloutis
University of Winnepeg, University of Winnepeg
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Jens Frydenvang
University of Copenhagen, University of Copenhagen
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Jonas L'Haridon
European Science Foundation, European Science Foundation
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Nicolas Mangold
LPGN/CNRS, University of Nantes, France, LPGN/CNRS, University of Nantes, France
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Lauren Ashley Edgar
USGS Astrogeology Science Center, USGS Astrogeology Science Center
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John P. Grotzinger
California Institute of Technology, California Institute of Technology
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Samantha Jacob
Arizona State University, Arizona State University
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Elizabeth B. Rampe
NASA Johnson Space Center, NASA Johnson Space Center
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Frances Rivera-Hernández
Dartmouth College, Dartmouth College
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Vivian Zheng Sun
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Lucy M Thompson
University of New Brunswick, University of New Brunswick
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Danika Wellington
School of Earth and Space Exploration, Arizona State University, School of Earth and Space Exploration, Arizona State University
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Abstract

Images from the Mars Science Laboratory (MSL) mission of lacustrine sedimentary rocks of Vera Rubin ridge on “Mt. Sharp” in Gale crater, Mars, have shown stark color variations from red to purple to gray. These color differences cross-cut stratigraphy and are likely due to diagenetic alteration of the sediments after deposition. However, the chemistry and timing of these fluid interactions is unclear. Determining how diagenetic processes may have modified chemical and mineralogical signatures of ancient martian environments is critical for understanding the past habitability of Mars and achieving the goals of the MSL mission. Here we use visible/near-infrared spectra from Mastcam and ChemCam to determine the mineralogical origins of color variations in the ridge. Color variations are consistent with changes in spectral properties related to the crystallinity, grain size, and texture of hematite. Coarse-grained gray hematite spectrally dominates in the gray patches and is present in the purple areas, while nanophase and fine-grained red crystalline hematite are present and spectrally dominate in the red and purple areas. We hypothesize that these differences were caused by grain size coarsening of hematite by diagenetic fluids, as observed in terrestrial analogs. In this model, early primary reddening by oxidizing fluids near the surface was followed during or after burial by bleaching to form the gray patches, possibly with limited secondary reddening after exhumation. Diagenetic alteration may have diminished the preservation of biosignatures and changed the composition of the sediments, making it more difficult to interpret how conditions evolved in the paleolake over time.
Nov 2020Published in Journal of Geophysical Research: Planets volume 125 issue 11. 10.1029/2019JE006322