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Mineralogy and geochemistry of sedimentary rocks and eolian sediments in Gale crater, Mars: A review after six Earth years of exploration with Curiosity

Rampe, E. B. and Grotzinger, J. P. (2020) Mineralogy and geochemistry of sedimentary rocks and eolian sediments in Gale crater, Mars: A review after six Earth years of exploration with Curiosity. Chemie der Erde - Geochemistry, 80 (2). Art. No. 125605. ISSN 0009-2819.

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The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity was sent to Gale crater to study a sequence of ∼3.5 Ga old sedimentary rocks that, based on orbital visible and near- to short-wave infrared reflectance spectra, contain secondary minerals that suggest deposition and/or alteration in liquid water. The sedimentary sequence in the lower slopes of Mount Sharp in Gale crater preserves a dramatic shift on early Mars from a relatively warm and wet climate to a cold and dry climate, based on a transition from smectite-bearing strata to sulfate-bearing strata. The rover is equipped with instruments to examine the sedimentology and identify compositional changes in the stratigraphy. The Chemistry and Mineralogy (CheMin) instrument is one of two internal laboratories on Curiosity and includes a transmission X-ray diffractometer (XRD) and X-ray fluorescence (XRF) spectrometer. CheMin measures loose sediment samples scooped from the surface and drilled rock powders, and the XRD provides quantitative mineralogy to a detection limit of ∼1 wt.% for crystalline phases. Curiosity has traversed >20 km since landing and has primarily been exploring an ancient lake environment fed by streams and groundwater. Of the 19 drilled rock samples analyzed by CheMin as of sol 2300 (January 2019), 15 are from fluvio-lacustrine deposits that comprise the Bradbury and Murray formations. Most of these samples were drilled from units that did not have a clear mineralogical signature from orbit. Results from CheMin demonstrate an astounding diversity in the mineralogy of these rocks that signifies geochemical variations in source rocks, transportation mechanisms, and depositional and diagenetic fluids. Most detrital igneous minerals are basaltic, but the discovery in a few samples of abundant silicate minerals that usually crystallize from evolved magmas on Earth remains enigmatic. Trioctahedral smectite and magnetite at the base of the section may have formed from low-salinity pore waters with a circumneutral pH in lake sediments. A transition to dioctahedral smectite, hematite, and Ca-sulfate going up section suggests a change to more saline and oxidative aqueous conditions in the lake waters themselves and/or in diagenetic fluids. Perhaps one of the biggest mysteries revealed by CheMin is the high abundance of X-ray amorphous materials (15 to 73 wt.%) in all samples drilled or scooped to date. CheMin has analyzed three modern eolian sands, which have helped constrain sediment transport and mineral segregation across the active Bagnold Dune Field. Ancient eolian sandstones drilled from the Stimson formation differ from modern eolian sands in that they contain abundant magnetite but no olivine, suggesting that diagenetic processes led to the alteration of olivine to release Fe(II) and precipitate magnetite. Fracture-associated halos in the Stimson and the Murray formations are evidence for complex aqueous processes long after the streams and lakes vanished from Gale crater. The sedimentology and composition of the rocks analyzed by Curiosity demonstrate that habitable environments persisted intermittently on the surface or in the subsurface of Gale crater for perhaps more than a billion years.

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Rampe, E. B.0000-0002-6999-0028
Grotzinger, J. P.0000-0001-9324-1257
Additional Information:© 2020 Published by Elsevier GmbH. Received 27 May 2019, Revised 23 December 2019, Accepted 18 January 2020, Available online 22 January 2020. We gratefully acknowledge the MSL engineering team for enabling the collection of these exceptional scientific datasets. We thank two anonymous reviewers for their thoughtful comments and thorough reviews that improved this manuscript. We also thank S. VanBommel for discussions that improved the manuscript. Some of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This work was supported in the U.S. by NASA’s Mars Exploration Program through the MSL mission. A portion of this research was supported by NASA NNX11AP82A, MSL Investigations, and by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1143953. J. R. Johnson acknowledges support from the MSL Participating Scientist Program subcontract 1546033. Any opinions, findings or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the National Aeronautics and Space Administration or the National Science Foundation. This Invited Review was solicited and handled by Associate Editor Klaus Keil.
Errata:The authors regret that the originally published affiliations were incorrect. The authors are not affiliated with Chesapeake Energy. The authors would like to apologise for any inconvenience caused.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1143953
Subject Keywords:Mars; Mineralogy; CheMin; Mars Science Laboratory
Issue or Number:2
Record Number:CaltechAUTHORS:20200124-141809165
Persistent URL:
Official Citation:E.B. Rampe, D.F. Blake, T.F. Bristow, D.W. Ming, D.T. Vaniman, R.V. Morris, C.N. Achilles, S.J. Chipera, S.M. Morrison, V.M. Tu, A.S. Yen, N. Castle, G.W. Downs, R.T. Downs, J.P. Grotzinger, R.M. Hazen, A.H. Treiman, T.S. Peretyazhko, D.J. Des Marais, R.C. Walroth, P.I Craig, J.A. Crisp, B. Lafuente, J.M. Morookian, P.C. Sarrazin, M.T. Thorpe, J.C. Bridges, L.A. Edgar, C.M. Fedo, C. Freissinet, R. Gellert, P.R. Mahaffy, H.E. Newsom, J.R. Johnson, L.C. Kah, K.L. Siebach, J. Schieber, V.Z. Sun, A.R. Vasavada, D. Wellington, R.C. Wiens, Mineralogy and geochemistry of sedimentary rocks and eolian sediments in Gale crater, Mars: A review after six Earth years of exploration with Curiosity, Geochemistry, Volume 80, Issue 2, 2020, 125605, ISSN 0009-2819, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100907
Deposited By: Tony Diaz
Deposited On:25 Jan 2020 03:27
Last Modified:23 Jun 2020 21:59

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