Oxidation State of Iron in SNC Meteorites as Studied by Mössbauer Spectroscopy

Vieira, V W A; Costa, T V V; Jensen, H. G.; Knudsen, J. M.; Olsen, M.; Vistisen, L.

doi:10.1088/0031-8949/33/2/016

Cited by 22 publications

(18 citation statements)

References 15 publications

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“…Perhaps the aliquot studied by Vieira et al was unusual in that it lacked titanomagentite. Vieira et al (1986) found only Fe 2+ pyroxene peaks in their paramagnetic fractions from Zagami.…”

Section: Previous Workmentioning

confidence: 93%

“…In a magnetic fraction separated from Nakhla, Vieira et al (1986) found magnetite, ilmenite, and ulvöspinel in small (unspecified) amounts. The Mössbauer spectrum from the paramagnetic fraction of Nakhla showed the presence of a small amount of Fe 3+ ; the amount was not specified by Vieira et al (1986), but the percentage of Fe 3+ in pyroxene was later estimated to be 2% (Vistisen et al 1990).…”

Section: Previous Workmentioning

confidence: 94%

“…The only workers to extract and analyze mineral separates were Ostertag et al (1983), Ostertag et al (1984;olivine), Vieira et al (1986), andVistisen et al (1990) (pyroxene). The olivines in ALH A77005 display a unique brown-yellow color, which was attributed by Ostertag et al (1984) to be preterrestrial and probably shock-induced.…”

Section: Previous Workmentioning

confidence: 99%

“…Data of Vieira et al (1986) demonstrated the presence of a small amount of magnetic phase in Zagami that was not magnetite and suggested that it might be pyrrhotite. This is puzzling given the petrographic studies of Stolper and McSween (1979), which found only 0.2-0.5% of the mode to be pyrrhotite and 2.1-2.2% to be titanomagnetite.…”

Section: Previous Workmentioning

confidence: 99%

“…The Mössbauer spectrum from the paramagnetic fraction of Nakhla showed the presence of a small amount of Fe 3+ ; the amount was not specified by Vieira et al (1986), but the percentage of Fe 3+ in pyroxene was later estimated to be 2% (Vistisen et al 1990).…”

Section: Previous Workmentioning

confidence: 99%

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Ferric iron in SNC meteorites as determined by Mössbauer spectroscopy: Implications for martian landers and martian oxygen fugacity

Dyar

2003

Meteorit & Planetary Scien

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Ferric iron in SNC meteorites as determined by Mössbauer spectroscopy:Implications for martian landers and martian oxygen fugacity Abstract-Mössbauer spectra of martian meteorites are currently of great interest due to the Mössbauer spectrometers on the Athena mission MER rovers as well as the European Space Agency Mars Express mission, with its Beagle 2 payload. Also, considerable current effort is being made to understand the oxygen fugacity of martian magmas because of the effect of fO 2 on mineral chemistry and crystallization processes. For these 2 reasons, the present study was conceived to acquire room temperature Mössbauer spectra of mineral separates and whole rock samples of 10 SNC meteorites.The results suggest that mineral identification using remote application of this technique will be most useful when the phases present have distinctive parameters arising from Fe in very different coordination polyhedra; for example, pyroxene coexisting with olivine can be discriminated easily, but opx versus cpx cannot. The MER goal of using Mössbauer spectroscopy to quantify the relative amounts of individual mineral species present will be difficult to satisfy if silicates are present because the lack of constraints on wt% FeO contents of individual silicate phases present will make modal calculations impossible. The remote Mössbauer spectroscopy will be most advantageous if the rocks analyzed are predominantly oxides with known stoichiometries, though these phases are not present in the SNCs. As for the detection of martian oxygen fugacity, no evidence exists in the SNC samples studied of a relationship between Fe 3+ content and fO 2 as calculated by independent methods. Possibly, all of the Fe 3+ observed in olivine is the result of dehydrogenation rather than oxidation, and this process may also be the source of all the Fe 3+ observed in pyroxene. The observed Fe 3+ in pyroxene also likely records an equilibrium between pyroxene and melt at such low fO 2 that little or no Fe 3+ would be expected.

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“…Perhaps the aliquot studied by Vieira et al was unusual in that it lacked titanomagentite. Vieira et al (1986) found only Fe 2+ pyroxene peaks in their paramagnetic fractions from Zagami.…”

Section: Previous Workmentioning

confidence: 93%

Section: Previous Workmentioning

confidence: 94%