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Analyses of High-Iron Sedimentary Bedrock and Diagenetic Features Observed With ChemCam at Vera Rubin Ridge, Gale Crater, Mars: Calibration and Characterization

David, G. and Cousin, A. and Forni, O. and Meslin, P.‐Y. and Dehouck, E. and Mangold, N. and L'Haridon, J. and Rapin, W. and Gasnault, O. and Johnson, J. R. and Ollila, A. M. and Newell, A. R. and Salvatore, M. and Gabriel, T. S. J. and Wiens, R. C. and Maurice, S. (2020) Analyses of High-Iron Sedimentary Bedrock and Diagenetic Features Observed With ChemCam at Vera Rubin Ridge, Gale Crater, Mars: Calibration and Characterization. Journal of Geophysical Research. Planets, 125 (10). Art. No. e2019JE006314. ISSN 2169-9097. doi:10.1029/2019je006314.

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Curiosity investigated a topographic rise named Vera Rubin Ridge (VRR) in Gale Crater, for which a distinct hematite‐like signature was observed from orbit. However, the Chemistry and Camera (ChemCam) and Alpha Particle x‐ray Spectrometer (APXS) instruments on board the rover did not record any significant iron enrichment in the bulk of the ridge compared to previous terrains. For this study, we have reverified ChemCam iron calibration at moderate abundances and developed more accurate calibrations at high‐iron abundances using iron‐oxide mixtures in a basaltic matrix in order to complete the ChemCam calibration database. The high‐iron calibration was first applied to the analysis of dark‐toned diagenetic features encountered at several locations on VRR, which showed that their chemical compositions are close to pure anhydrous iron oxides. Then, we tracked iron abundances in the VRR bedrock and demonstrated that although there is no overall iron enrichment in the bulk of the ridge (21.2 ± 1.8‐wt.% FeO_T) compared to underlying terrains, the iron content is more variable in its upper section with areas of enhanced iron abundances in the bedrock (up to 26.6 ± 0.85‐wt.% FeO_T). Since the observed variability in iron abundances does not conform to the stratigraphy, the involvement of diagenetic fluid circulation was likely. An in‐depth chemical study of these Fe‐rich rocks reveals that spatial gradients in redox potential (Eh) may have driven iron mobility and reactions that precipitated and accumulated iron oxides. We hypothesize that slightly reducing fluids were probably involved in transporting ferrous iron. Mobile Fe²⁺ could have precipitated as iron oxides in more oxidizing conditions.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemData
David, G.0000-0002-2719-1586
Cousin, A.0000-0001-7823-7794
Forni, O.0000-0001-6772-9689
Meslin, P.‐Y.0000-0002-0703-3951
Dehouck, E.0000-0002-1368-4494
Mangold, N.0000-0002-0022-0631
L'Haridon, J.0000-0002-9323-1603
Rapin, W.0000-0003-4660-8006
Gasnault, O.0000-0002-6979-9012
Johnson, J. R.0000-0002-5586-4901
Ollila, A. M.0000-0003-0479-9465
Salvatore, M.0000-0002-1551-8342
Gabriel, T. S. J.0000-0002-9767-4153
Wiens, R. C.0000-0002-3409-7344
Maurice, S.0000-0001-5702-8002
Additional Information:© 2020 American Geophysical Union. Issue Online: 09 October 2020; Version of Record online: 09 October 2020; Accepted manuscript online: 10 August 2020; Manuscript accepted: 21 July 2020; Manuscript revised: 18 July 2020; Manuscript received: 04 December 2019. We are grateful to the MSL science and operation teams who developed the rover and collected data. Funding for the ChemCam instrument and operations was provided by the NASA Mars Exploration Program in the United States and by the Centre National d'Etude Spatiales (CNES) and the Centre National de la Recherche Scientifique (CNRS) in France. Data Availability Statement: All the ChemCam data used in this paper are released and can be found on the Planetary Data System ( Laboratory LIBS experiments were conducted at the Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France, and at the Los Alamos National Laboratory (LANL), USA, and data can be found respectively in David (2020a, 2020b). Information about laboratory samples and VRR targets can be in the supplementary tables and are also available from David (2020c).
Funding AgencyGrant Number
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:Mars; ChemCam; Vera Rubin ridge; iron oxides; iron mobility
Issue or Number:10
Record Number:CaltechAUTHORS:20200818-124404023
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Official Citation:David, G., Cousin, A., Forni, O., Meslin, P.‐Y., Dehouck, E., Mangold, N., et al. (2020). Analyses of high‐iron sedimentary bedrock and diagenetic features observed with ChemCam at Vera Rubin Ridge, Gale Crater, Mars: Calibration and characterization. Journal of Geophysical Research: Planets, 125, e2019JE006314.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105001
Deposited By: Tony Diaz
Deposited On:18 Aug 2020 21:29
Last Modified:16 Nov 2021 18:38

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