Petrogenetic relationship between Allan Hills 77005 and other achondrites

McSween, H. Y.; Stolper, Edward M.; Taylor, L. A.; Muntean, R. A.; O'Kelley, G.D.; Eldridge, J. S.; Biswas, S.; Ngo, H. T.; Lipschutz, M. E.

doi:10.1016/0012-821x(79)90129-8

Cited by 81 publications

(32 citation statements)

References 29 publications

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“…This is consistent with the common interpretation that the poikilitic areas formed first and the non-poikilitic areas are interstitial (McSween et al 1979b;Lundberg et al 1990). However, the observation that the chromites in olivine have lower Cr#s than those in the pigeonite (Fig.…”

Section: Crystallization Of Spinels In Alh A77005supporting

confidence: 80%

Spinels and oxygen fugacity in olivine‐phyric and lherzolitic shergottites

Goodrich

Herd

Taylor

2003

Meteorit & Planetary Scien

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125

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Spinels and oxygen fugacity in olivine-phyric and lherzolitic shergottitesAbstract-We examine the occurrences, textures, and compositional patterns of spinels in the olivinephyric shergottites Sayh al Uhaymir (SaU) 005, lithology A of Elephant Moraine A79001 (EET-A), Dhofar 019, and Northwest Africa (NWA) 1110, as well as the lherzolitic shergottite Allan Hills (ALH) A77005, in order to identify spinel-olivine-pyroxene assemblages for the determination of oxygen fugacity (using the oxybarometer of Wood [1991]) at several stages of crystallization. In all of these basaltic martian rocks, chromite was the earliest phase and crystallized along a trend of strict Cr-Al variation. Spinel (chromite) crystallization was terminated by the appearance of pyroxene but resumed later with the appearance of ulvöspinel. Ulvöspinel formed overgrowths on early chromites (except those shielded as inclusions in olivine or pyroxene), retaining the evidence of the spinel stability gap in the form of a sharp core/rim boundary (except in ALH A77005, where subsolidus reequilibration diffused this boundary). Secondary effects seen in chromites include reaction with melt before ulvöspinel overgrowth, reaction with melt inclusions, reaction with olivine hosts (in ALH A77005), and exsolution of ulvöspinel or ilmenite. All chromites experienced subsolidus Fe/Mg reequilibration. Spinel-olivine-pyroxene assemblages representing the earliest stages of crystallization in each rock essentially consist of the highest-Cr#, lowest-fe# chromites not showing secondary effects plus the most magnesian olivine and equilibrium low-Ca pyroxene. Assemblages representing the onset of ulvöspinel crystallization consist of the lowest-Ti ulvöspinel, the most magnesian olivine in which ulvöspinel occurs as inclusions, and equilibrium low-Ca pyroxene.The results show that, for early crystallization conditions, oxygen fugacity (fO 2 ) increases from SaU 005 and Dhofar 019 (~QFM -3.8), to EET-A (QFM -2.8) and ALH A77005 (QFM -2.6), to NWA 1110 (QFM -1.7). Estimates for later conditions indicate that in SaU 005 and Dhofar 019 oxidation state did not change during crystallization. In EET-A, there was an increase in fO 2 that may have been due to mixing of reduced material with a more oxidized magma. In NWA 1110, there was a dramatic increase, indicating a non-buffered system, possibly related to its high oxidation state. Differences in fO 2 among shergottites are not primarily due to igneous fractionation but, rather, to derivation from (and possibly mixing of) different reservoirs.

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Section: Crystallization Of Spinels In Alh A77005supporting

confidence: 80%

Spinels and oxygen fugacity in olivine‐phyric and lherzolitic shergottites

Goodrich

Herd

Taylor

2003

Meteorit & Planetary Scien

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125

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“…McSween et al 1979;Mason 1981;Goodrich 2003). They are cumulates with euhedral olivines typically poikilitically enclosed by pigeonites or augites up to 5 mm across.…”

Section: Peridotitic (Lherzolite) Shergottitesmentioning

confidence: 99%

“…McSween et al 1979;Wood & Ashwal 1981). However, suggestions that some meteorites might be derived from Mars can be traced back further (e.g.…”

mentioning

confidence: 99%

The SNC meteorites: basaltic igneous processes on Mars

Bridges

Warren²

2006

JGS

135

128

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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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“…In many prior studies, we have shown that our suite of 15 trace elements (U, Au, Co, Sb, Ga, Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, TI, and In, ordered by increasing putative volatility in a nebular setting), determined using radiochemical neutron activation analyses (RNAA), can illuminate many aspects of the thermal histories of meteorites and their parent bodies (e.g., Wolf and Lipschutz (1997) and references therein). We had previously reported whole-rock data for seven of the Martian meteorite suite (McSween et al, 1979;Biswas et al, 1980;Smith et al, 1984;Laul et al, 1986;Treiman et al, 1994;Mittlefehldt et al, 1997), and we felt it worthwhile to obtain data for the remaining five of the suite which we report here.…”

Section: Introductionmentioning

confidence: 99%

Martian meteorites: Volatile trace elements and cluster analysis

Wang

Mokos

Lipschutz

1998

Meteorit & Planetary Scien

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Abstract-We report data for 15 mainly volatile trace elements (Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, T1, U, Zn) by radiochemical neutron activation analysis (RNAA) in whole-rock samples of five Martian meteorites that, with seven others studied earlier, complete the 12 member Martian meteorite suite. Nearly all of these elements exhibit highly variable compositional continua and are richer in the Martian suite compared with other basaltic meteorites. From cluster analysis, we find that the clustering of subtypes based on these elements is virtually identical to that based on contents of major refractory elements and mineralogic/petrographic characteristics, which implies that each source region on Mars was closed to volatile transport. Martian meteorite data can be used to infer volatile element contents in that planet.

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Petrogenetic relationship between Allan Hills 77005 and other achondrites

Cited by 81 publications

References 29 publications

Spinels and oxygen fugacity in olivine‐phyric and lherzolitic shergottites

Spinels and oxygen fugacity in olivine‐phyric and lherzolitic shergottites

The SNC meteorites: basaltic igneous processes on Mars

Martian meteorites: Volatile trace elements and cluster analysis

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