Composition of conglomerates analyzed by the Curiosity rover: Implications for Gale Crater crust and sediment sources
- Creators
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Mangold, N.
- Thompson, L. M.
- Forni, O.
- Williams, A. J.
- Fabre, C.
- Le Deit, L.
- Wiens, R. C.
- Williams, R.
- Anderson, R. B.
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Blaney, D. L.
- Calef, F.
- Cousin, A.
- Clegg, S. M.
- Dromart, G.
- Dietrich, W. E.
- Edgett, K. S.
- Fisk, M. R.
- Gasnault, O.
- Gellert, R.
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Grotzinger, J. P.
- Kah, L.
- Le Mouélic, S.
- McLennan, S. M.
- Maurice, S.
- Meslin, P.-Y.
- Newsom, H. E.
- Palucis, M. C.
- Rapin, W.
- Sautter, V.
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Siebach, K. L.
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Stack, K.
- Sumner, D.
- Yingst, A.
Abstract
The Curiosity rover has analyzed various detrital sedimentary rocks at Gale Crater, among which fluvial and lacustrine rocks are predominant. Conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration, enabling us to link their chemistry to that of source rocks on the Gale Crater rims. In this study, we report the results of six conglomerate targets analyzed by Alpha‐Particle X‐ray Spectrometer and 40 analyzed by ChemCam. The bulk chemistry derived by both instruments suggests two distinct end‐members for the conglomerate compositions. The first group (Darwin type) is typical of conglomerates analyzed before sol 540; it has a felsic alkali‐rich composition, with a Na₂O/K₂O > 5. The second group (Kimberley type) is typical of conglomerates analyzed between sols 540 and 670 in the vicinity of the Kimberley waypoint; it has an alkali‐rich potassic composition with Na₂O/K₂O < 2. The variety of chemistry and igneous textures (when identifiable) of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks. Conglomerate compositions are in agreement with most of the felsic alkali‐rich float rock compositions analyzed in the hummocky plains. The average composition of conglomerates can be taken as a proxy of the average igneous crust composition at Gale Crater. Differences between the composition of conglomerates and that of finer‐grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes (especially for Mg enrichments in fine‐grained rocks), physical sorting, and mixing with finer‐grained material of different composition.
Additional Information
© 2016 American Geophysical Union. Issue Online: 15 April 2016; Version of Record online: 16 March 2016; Accepted manuscript online: 04 March 2016; Manuscript accepted: 25 February 2016; Manuscript revised: 23 February 2016; Manuscript received: 05 November 2015. We are grateful to Marjorie Chan and two anonymous reviewers for their insightful comments. Development and operation of the ChemCam instrument was supported in France by funds from the French space agency, Centre National d'Etudes Spatiales (CNES). Support for development and operation in the U.S. was provided by NASA to the Mars Exploration Program and specifically to the MSL team. The APXS is managed and financed by the Canadian Space Agency (CSA). Imaging and chemical data presented here are available in the NASA Planetary Data System (PDS) http://pds‐geosciences.wustl.edu/missions/msl. We are grateful to the MSL engineering and management teams (and especially the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA) for making the mission and this scientific investigation possible and to science team members who contributed to mission operations.Attached Files
Published - 2015JE004977.pdf
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Additional details
- Eprint ID
- 105219
- Resolver ID
- CaltechAUTHORS:20200902-130428741
- Centre National d'Études Spatiales (CNES)
- NASA/JPL/Caltech
- Canadian Space Agency (CSA)
- Created
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2020-09-08Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences