Oxygen fugacity of martian basalts from electron microprobe oxygen and TEM-EELS analyses of Fe-Ti oxides

Herd, C. D. K.; Papike, J. J.; Brearley, Adrian J.

doi:10.2138/am-2001-8-908

Cited by 129 publications

(142 citation statements)

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“…Line is the fit to dataset of Herd (2003) but more recent additions show that this is more complicated. Oxygen fugacity data are from Goodrich et al 2003;Herd et al 2001Herd et al , 2002Herd 2003Herd , 2006McCanta et al (2004b);Wadhwa 2001;Karner et al 2007;Shearer et al 2006; La and Yb data are from references compiled by C. Meyer, Mars Meteorite Compendium 2008 webpage). Conversion between IW and FMQ buffers was done using calibration of O'Neill (1988) for IW and O'Neill (1987) for FMQ; at magmatic temperatures the relative difference is ~3.5 log fO 2 units.…”

Section: Mineral Composition and Structurementioning

confidence: 99%

Oxygen fugacity in the Martian mantle controlled by carbon: New constraints from the nakhlite MIL 03346

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Yang

Costin

et al. 2008

Meteorit & Planetary Scien

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This trend can be explained by polybaric graphite-CO-CO 2 equilibria in the Martian mantle. Shergottites would have formed at pressures between 1.2 and 3.0 GPa, and nakhlite parent liquids formed at pressures >3.0 GPa, consistent with geochemical and petrologic data for the shergottites and nahklites. Carbon buffering in the Martian mantle could be responsible for variation in fO 2 in Martian meteorites (rather than assimilation or crustal interaction), as well as C-H-O fluids that could be the source of ~30 ppb CH 4 detected by recent spacecraft missions. The conundrum of an oxidized current mantle and basalts, but reduced early mantle during core-mantle equilibrium exists for both the Earth and Mars. A polybaric buffering role for graphite can explain this discrepancy for Mars, and thus it may not be necessary to have an oxidation mechanism like the dissociation of MgFe-perovskite to account for the oxidized terrestrial mantle.

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Section: Mineral Composition and Structurementioning

confidence: 99%

Oxygen fugacity in the Martian mantle controlled by carbon: New constraints from the nakhlite MIL 03346

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Yang

Costin

et al. 2008

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“…Recent studies of shergottites (Herd et al 2001(Herd et al , 2002Wadhwa 2001;Goodrich et al 2003;Herd 2003) have added an important new constraint by documenting a correlation between geochemical depletion or enrichment and oxygen fugacity (Fig. 15).…”

Section: Magma Sourcesmentioning

confidence: 99%

The SNC meteorites: basaltic igneous processes on Mars

Bridges

Warren²

2006

JGS

135

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A group of 32 meteorites, the SNC (Shergotty, Nakhla, Chassigny) group, was derived from Mars as a product of 4-7 ejection events, probably from Tharsis and Elysium-Amazonis. The SNCs either have basaltic mineralogy or some are ultramafic cumulates crystallized from basaltic melts. The SNCs can be classified both petrographically and geochemically. We classify the shergottite SNC meteorites on the basis of their light rare earth element (LREE) depletion into highly depleted, moderately depleted and slightly depleted. The slightly depleted samples (which are mainly but not exclusively aphyric basalts) show high log 10 f O 2 values (QFM À1.0, where QFM is quartz-fayalite-magnetite). Highly depleted samples, which are mainly olivine-phyric basalts, have low log 10 f O 2 values (QFM À3.5). On the basis of mixing calculations between La/Lu and 87 Sr/ 86 Sr we favour models linking the correlation between LREE abundances and log 10 f O 2 to mantle heterogeneity rather than contamination by oxidized, LREE-rich crustal fluids. SNC chemistry in general reflects the Fe-rich mantle of Mars (which contains twice as much FeO as the Earth's mantle), the late accretion of chondritic material into the mantle, and possibly the presence of a plagioclaserich magma ocean, which acted to variably deplete the mantle in Al. The high FeO contents of the SNC melts are associated with high melt densities (allowing the ponding of large magma bodies) and low viscosities, both of which are consistent with the large scale of many observed martian lava flows.Of the approximately 30 000 currently known meteorites, 32 originated on Mars. The martian meteorites are also called the SNC group after three of its members: Shergotty, Nakhla, Chassigny. They are known to form a distinct group of meteorites from a single parent body on the basis of their relatively differentiated mineralogy and chemical compositions; oxygen isotope compositions that are related to each other by mass fractionation (e.g. Clayton & Mayeda 1996); high oxidation state for meteorites (log f O 2 between QFM (quartz-fayalite-magnetite) and IW (iron-wüstite); e.g. Herd 2003) and notably large range of crystallization ages (165 Ma to 4.5 Ga; Nyquist et al. 2001a).It is the crystallization ages that first led to wide acceptance that this meteorite group was derived from a large, slowly cooled planet, Mars (e.g. McSween et al. 1979;Wood & Ashwal 1981). However, suggestions that some meteorites might be derived from Mars can be traced back further (e.g. Wänke 1968). Papanastassiou & Wasserburg (1974) noted that one of the SNC meteorites (Nakhla) must have been derived from an (unspecified) planetary object with some affinities to the Earth that had undergone differentiation after 3.6 Ga. The definitive link to Mars was made through comparing the composition of gases within the shock-melted glass of shergottites with the composition of the martian atmosphere determined by the Viking landers (Bogard & Johnson 1983).The SNCs have a range of basaltic and ultramafic mineral as...

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“…Slow cooling may have compromised oxide oxybarometry as it has been demonstrated that Fe-Ti oxides can reequilibrate in the subsolidus (Lindsley et al 1991;Treiman and Irving 2008), leading to non-magmatic fO 2 estimates (Ghosal et al 1998). Reequilibration may also have affected other oxybarometers, such as olivine-pyroxenespinel (Herd et al 2001). Additionally, the lack of a remaining melt phase rules out melt-based fO 2 methods.…”

Section: Introductionmentioning

confidence: 99%

Expanding the application of the Eu‐oxybarometer to the lherzolitic shergottites and nakhlites: Implications for the oxidation state heterogeneity of the Martian interior

McCanta¹,

Elkins-Tanton²,

Rutherford³

2009

Meteorit & Planetary Scien

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Oxygen fugacity of martian basalts from electron microprobe oxygen and TEM-EELS analyses of Fe-Ti oxides

Cited by 129 publications

References 20 publications

Oxygen fugacity in the Martian mantle controlled by carbon: New constraints from the nakhlite MIL 03346

Oxygen fugacity in the Martian mantle controlled by carbon: New constraints from the nakhlite MIL 03346

The SNC meteorites: basaltic igneous processes on Mars

Expanding the application of the Eu‐oxybarometer to the lherzolitic shergottites and nakhlites: Implications for the oxidation state heterogeneity of the Martian interior

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