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Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Mossbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits
Author(s): Morris, Richard Van
Klingelhoefer, Goestar
Schröder, Christian
Rodionov, Daniel S
Yen, Albert S
Ming, Douglas Wayne
de Souza Jr, Paulo A
Wdowiak, Thomas J
Fleischer, Iris
Gellert, Ralf
Bernhardt, Bodo
Bonnes, U
Cohen, Barbara A
Evlanov, E N
Foh, J
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Keywords: Mars
Mars Exploration Rover
Meridiani Planum
Issue Date: 30-Dec-2006
Date Deposited: 28-Oct-2013
Citation: Morris RV, Klingelhoefer G, Schröder C, Rodionov DS, Yen AS, Ming DW, de Souza Jr PA, Wdowiak TJ, Fleischer I, Gellert R, Bernhardt B, Bonnes U, Cohen BA, Evlanov EN & Foh J (2006) Mossbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits. Journal of Geophysical Research: Planets, 111 (E12), Art. No.: E12S15.
Abstract: The Mössbauer (MB) spectrometer on Opportunity measured the Fe oxidation state, identified Fe-bearing phases, and measured relative abundances of Fe among those phases at Meridiani Planum, Mars. Eight Fe-bearing phases were identified: jarosite (K,Na,H3O)(Fe,Al)(OH)6(SO4)2, hematite, olivine, pyroxene, magnetite, nanophase ferric oxides (npOx), an unassigned ferric phase, and metallic Fe (kamacite). Burns Formation outcrop rocks consist of hematite-rich spherules dispersed throughout S-rich rock that has nearly constant proportions of Fe3+ from jarosite, hematite, and npOx (29%, 36%, and 20% of total Fe). The high oxidation state of the S-rich rock (Fe3+/FeT ~ 0.9) implies that S is present as the sulfate anion. Jarosite is mineralogical evidence for aqueous processes under acid-sulfate conditions because it has structural hydroxide and sulfate and it forms at low pH. Hematite-rich spherules, eroded from the outcrop, and their fragments are concentrated as hematite-rich soils (lag deposits) on ripple crests (up to 68% of total Fe from hematite). Olivine, pyroxene, and magnetite are primarily associated with basaltic soils and are present as thin and locally discontinuous cover over outcrop rocks, commonly forming aeolian bedforms. Basaltic soils are more reduced (Fe3+/FeT ~ 0.2–0.4), with the fine-grained and bright aeolian deposits being the most oxidized. Average proportions of total Fe from olivine, pyroxene, npOx, magnetite, and hematite are 33%, 38%, 18%, 6%, and 4%, respectively. TheMB parameters of outcrop npOx and basaltic-soil npOx are different, but it is not possible to infer mineralogical information beyond octahedrally coordinated Fe3+. Basaltic soils at Meridiani Planum and Gusev crater have similar Fe-mineralogical compositions.
DOI Link: 10.1029/2006JE002791
Rights: Copyright 2006 by the American Geophysical Union. AGU allows authors to deposit their journal articles if the version is the final published citable version of record, the AGU copyright statement is clearly visible on the posting, and the posting is made 6 months after official publication by the AGU.
Notes: Additonal co-authors: P Gütlich, E Kankeleit, T McCoy, DW Mittlefehldt, F Renz, ME Schmidt, B Zubkov, SW Squyres, RE Arvidson

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