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Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars

Nachon, M. and Grotzinger, J. P. (2017) Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars. Icarus, 281 . pp. 121-136. ISSN 0019-1035. doi:10.1016/j.icarus.2016.08.026.

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The Curiosity rover's campaign at Pahrump Hills provides the first analyses of lower Mount Sharp strata. Here we report ChemCam elemental composition of a diverse assemblage of post-depositional features embedded in, or cross-cutting, the host rock. ChemCam results demonstrate their compositional diversity, especially compared to the surrounding host rock: (i) Dendritic aggregates and relief enhanced features, characterized by a magnesium enhancement and sulfur detection, and interpreted as Mg-sulfates; (ii) A localized observation that displays iron enrichment associated with sulfur, interpreted as Fe-sulfate; (iii) Dark raised ridges with varying Mg- and Ca-enriched compositions compared to host rock; (iv) Several dark-toned veins with calcium enhancement associated with fluorine detection, interpreted as fluorite veins. (v) Light-toned veins with enhanced calcium associated with sulfur detection, and interpreted as Ca-sulfates. The diversity of the Pahrump Hills diagenetic assemblage suggests a complex post-depositional history for fine-grained sediments for which the origin has been interpreted as fluvial and lacustrine. Assessment of the spatial and relative temporal distribution of these features shows that the Mg-sulfate features are predominant in the lower part of the section, suggesting local modification of the sediments by early diagenetic fluids. In contrast, light-toned Ca-sulfate veins occur in the whole section and cross-cut all other features. A relatively late stage shift in geochemical conditions could explain this observation. The Pahrump Hills diagenetic features have no equivalent compared to targets analyzed in other locations at Gale crater. Only the light-toned Ca-sulfate veins are present elsewhere, along Curiosity's path, suggesting they formed through a common late-stage process that occurred at over a broad area.

Item Type:Article
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Nachon, M.0000-0003-0417-7076
Grotzinger, J. P.0000-0001-9324-1257
Additional Information:© 2016 Elsevier Inc. Received 18 December 2015, Revised 16 August 2016, Accepted 26 August 2016, Available online 1 September 2016. Data used in the study are available at the NASA Planetary Data System ( We are grateful to the MSL and especially ChemCam science and engineering Teams for the data collection, which is supported in the US by NASA's Mars Exploration Program. We acknowledge Jean-Pierre Lorand (LPGNantes) for providing us with the NiS sample. We also acknowledge the IRAP and the CNES Team members for their contribution on the laboratory analysis. Insightful comments provided by two anonymous reviewers were appreciated. French authors are granted by the Centre National de la Recherche Scientifique, the Centre National d'Etudes Spatiales, and the Observatoire des Sciences de l'Univers Nord Atlantique.
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Centre National d’Etudes Spatiales (CNES)UNSPECIFIED
Observatoire des Sciences de l'Univers Nord AtlantiqueUNSPECIFIED
Subject Keywords:Mars surface; Geological processes; Mineralogy
Record Number:CaltechAUTHORS:20161104-100515528
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Official Citation:M. Nachon, N. Mangold, O. Forni, L.C. Kah, A. Cousin, R.C. Wiens, R. Anderson, D. Blaney, J.G. Blank, F. Calef, S.M. Clegg, C. Fabre, M.R. Fisk, O. Gasnault, J.P. Grotzinger, R. Kronyak, N.L. Lanza, J. Lasue, L. Le Deit, S. Le Mouélic, S. Maurice, P.-Y. Meslin, D.Z. Oehler, V. Payré, W. Rapin, S. Schröder, K. Stack, D. Sumner, Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars, Icarus, Volume 281, 1 January 2017, Pages 121-136, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71740
Deposited By: Tony Diaz
Deposited On:04 Nov 2016 19:11
Last Modified:11 Nov 2021 04:50

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