Chemistry and mineralogy of outcrops at Meridiani Planum

Clark, B. C. and Morris, R. V. and McLennan, S. M. and Gellert, R. and Jolliff, B. and Knoll, A. H. and Squyres, S. W. and Lowenstein, T. K. and Ming, D. W. and Tosca, N. J. and Yen, A. and Christensen, P. R. and Gorevan, S. and Calvin, W. and Dreibus, G. and Farrand, W. and Klingelhoefer, G. and Waenke, H. and Zipfel, J. and Bell Iii, J. F. and Grotzinger, J. and McSween, H. Y. and Rieder, R. (2005) Chemistry and mineralogy of outcrops at Meridiani Planum. Earth and Planetary Science Letters, 240 (1). pp. 73-94. ISSN 0012-821X DOI 10.1016/j.epsl.2005.09.040

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Abstract

Analyses of outcrops created by the impact craters Endurance, Fram and Eagle reveal the broad lateral continuity of chemical sediments at the Meridiani Planum exploration site on Mars. Approximately ten mineralogical components are implied in these salt-rich silicic sediments, from measurements by instruments on the Opportunity rover. Compositional trends in an apparently intact vertical stratigraphic sequence at the Karatepe West ingress point at Endurance crater are consistent with non-uniform deposition or with subsequent migration of mobile salt components, dominated by sulfates of magnesium. Striking variations in Cl and enrichments of Br, combined with diversity in sulfate species, provide further evidence of episodes during which temperatures, pH, and water to rock ratios underwent significant change. To first order, the sedimentary sequence examined to date is consistent with a uniform reference composition, modified by movement of major sulfates upward and of minor chlorides downward. This reference composition has similarities to martian soils, supplemented by sulfate anion and the alteration products of mafic igneous minerals. Lesser cementation in lower stratigraphic units is reflected in decreased energies for grinding with the Rock Abrasion Tool. Survival of soluble salts in exposed outcrop is most easily explained by absence of episodes of liquid H2O in this region since the time of crater formation. B) 2005 Elsevier B.V. All rights reserved.

Item Type:	Article
Uncontrolled Keywords:	IA58
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title:	Earth and Planetary Science Letters
Volume:	240
Page Range:	pp. 73-94
Identification Number:	10.1016/j.epsl.2005.09.040
Depositing User:	Sarah Humbert
Date Deposited:	17 Dec 2009 13:06
Last Modified:	23 Jul 2013 09:56
URI:	http://eprints.esc.cam.ac.uk/id/eprint/1233

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