Iron Mobility During Diagenesis at Vera Rubin Ridge, Gale Crater, Mars
Abstract
The Curiosity rover investigated a topographic structure known as Vera Rubin ridge, associated with a hematite signature in orbital spectra. There, Curiosity encountered mudstones interpreted as lacustrine deposits, conformably overlying the 300 m‐thick underlying sedimentary rocks of the Murray formation at the base of Mount Sharp. While the presence of hematite (α‐Fe2O3) was confirmed in situ by both Mastcam and ChemCam spectral observations and by the CheMin instrument, neither ChemCam nor APXS observed any significant increase in FeOT (total iron oxide) abundances compared to the rest of the Murray formation. Instead, Curiosity discovered dark‐toned diagenetic features displaying anomalously high FeOT abundances, commonly observed in association with light‐toned Ca‐sulfate veins but also as crystal pseudomorphs in the host rock. These iron‐rich diagenetic features are predominantly observed in "gray" outcrops on the upper part of the ridge, which lack the telltale ferric signature of other Vera Rubin ridge outcrops. Their composition is consistent with anhydrous Fe‐oxide, as the enrichment in iron is not associated with enrichment in any other elements, nor with detections of volatiles. The lack of ferric absorption features in the ChemCam reflectance spectra and the hexagonal crystalline structure associated with dark‐toned crystals points toward coarse "gray" hematite. In addition, the host rock adjacent to these features appears bleached and shows low‐FeOT content as well as depletion in Mn, indicating mobilization of these redox‐sensitive elements during diagenesis. Thus, groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on Vera Rubin ridge.
Additional Information
© 2020 American Geophysical Union. Issue Online: 13 November 2020; Version of Record online: 13 November 2020; Accepted manuscript online: 28 August 2020; Manuscript accepted: 08 August 2020; Manuscript revised: 04 August 2020; Manuscript received: 29 November 2019. We are indebted to the Mars Science Laboratory Project engineering and science teams for their participations in tactical and strategic operations. All data used in this study are accessible at the Planetary Data System (http://pds‐geosciences.wustl.edu/missions/msl/index.htm). Data provided by the ChemCam instrument are supported in the United States by NASA's Mars Exploration Program and in France by the Centre National d'Etudes Spatiales (CNES) and the Agence Nationale de la Recherche (ANR) under the program ANR‐16‐CE31‐0012 entitled "Mars‐Prime." J. Frydenvang acknowledges the support of the Carlsberg Foundation.Attached Files
Published - 2019JE006299.pdf
Supplemental Material - jgre21470-sup-0001-2019je006299-si.xlsx
Supplemental Material - jgre21470-sup-0002-figs01-figs02.docx
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Additional details
- Eprint ID
- 105200
- Resolver ID
- CaltechAUTHORS:20200901-103430744
- Centre National d'Études Spatiales (CNES)
- ANR-16-CE31-0012
- Agence Nationale pour la Recherche (ANR)
- Carlsberg Foundation
- Created
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2020-09-08Created from EPrint's datestamp field
- Updated
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2023-03-16Created from EPrint's last_modified field