Chronology and petrogenesis of young achondrites, Shergotty, Zagami, and ALHA77005: late magmatism on a geologically active planet

Shih, C. Y.; Nyquist, L. E.; Bogard, D. D.; McKay, G.; Wooden, Joseph L.; Bansal, B. M.; Wiesmann, H.

doi:10.1016/0016-7037(82)90205-8

Cited by 228 publications

(128 citation statements)

References 37 publications

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“…The core composition is similar to the calculated composition for a pyroxene in equilibrium with a melt with the bulk composition of QUE 94201. In contrast, the core compositions of pyroxene (Stolper and McSween 1979;McSween and Jarosewich 1983;McCoy et al 1992) are not similar to the calculated compositions for pyroxene in equilibrium with melts with the bulk composition (Shih et al 1982;Burghele et al 1983;McSween and Jarosewich 1983;Smith et al 1984) of Shergotty, Zagami, and EET 79001, with the possible exception of lithology B of EET 79001. Fig.…”

Section: Liquid Line Of Descentmentioning

confidence: 62%

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

Kring

Gleason

Swindle

et al. 2003

Meteorit & Planetary Scien

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Abstract-Antarctic meteorite Queen Alexandra Range (QUE) 94201 is a 12 g basaltic achondrite dominated by plagioclase (now maskelynite) and zoned low-and high-Ca pyroxene. Petrologic, geochemical, and isotopic analyses indicate that it is related to previously described basaltic and lherzolitic shergottites, which are a group of igneous meteorites that are believed to be from Mars. Unlike previous shergottites, however, QUE 94201 represents a bulk melt rather than a cumulate fraction, meaning it can be used to infer magmatic source regions and the compositions of other melts on Mars. This melt has much more Fe and P than basaltic melts produced on Earth and formed at a much lower oxygen fugacity. This has altered the crystallization sequence of the melt, removing olivine from the liquidus to produce a plagioclase and 2-pyroxene assemblage. If the high-phosphorus and low-oxygen fugacity conditions represented by QUE 94201 are common in magmatic regions of Mars, then olivine may be rare in martian basalts. No solar cosmic ray effects were seen in the concentrations of 10 Be, 26 Al, and 36 Cl with depth in the meteorite, implying at least 3 cm of ablation during entry to Earth. Significant excesses of neutron capture noble gas isotopes ( 80, 82 Kr and 128, 131 Xe) suggest that the QUE 94201 sample came from a depth >22 cm in a meteoroid of at least that radius. The meteorite also has very low 21 Ne/ 22 Ne, which would often be interpreted to mean little ablation (contradicting above evidence) but, in this case, appears to reflect a very low abundance of Mg (the principal target element for Ne) in the meteorite, consistent with our bulk chemical analyses.The meteorite has a terrestrial 36 Cl age of 0.29 ± 0.05 Myr and a 10 Be exposure age of 2.6 ± 0.5 Myr in a 4π geometry, implying an ejection age of 2.9 ± 0.5 Myr.

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Section: Liquid Line Of Descentmentioning

confidence: 62%

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

Kring

Gleason

Swindle

et al. 2003

Meteorit & Planetary Scien

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“…Abundant geochemical data are available for the shergottites (as summarized by McSween and Treiman, 1998;Meyer, 2009 http:// curator.jsc.nasa.gov/antmet/mmc/index.cfm), including mineral compositions (e.g., Wadhwa et al, 1994), trace elements (e.g., Treiman et al, 1986), and various isotopic ratios (e.g., Shih et al, 1982;Borg et al, 2002).…”

Section: Shergottitesmentioning

confidence: 99%

The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites

Schmidt

McCoy

2010

Earth and Planetary Science Letters

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“…Ar is given in units of 10 −6 cc STP/g, Xe in 10 −12 cc STP/g. Stöffler et al (1986): average of all given analyses (min, max); b Terribilini et al (1998); c Smith and Hervig (1979); d Hale et al (1999); e Stolper and McSween (1979); f Bogard and Garrison (1999); g Shih et al 1982;h Treiman and Sutton (1991): range of all given analyses; i Steele and Smith (1982): range of all given analyses. Estimates of radiogenic 40 Ar are given in units of 10 −6 cc STP/g.…”

Section: Martian Interior Argonmentioning

confidence: 99%

Noble gases in mineral separates from three shergottites: Shergotty, Zagami, and EETA79001

Schwenzer¹,

Herrmann²,

Mohapatra

et al. 2007

Meteorit & Planetary Scien

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Abstract-This study provides a complete data set of all five noble gases for bulk samples and mineral separates from three Martian shergottites: Shergotty (bulk, pyroxene, maskelynite), Zagami (bulk, pyroxene, maskelynite), and Elephant Moraine (EET) A79001, lithology A (bulk, pyroxene). We also give a compilation of all noble gas and nitrogen studies performed on these meteorites. Our mean values for cosmic-ray exposure ages from 3 He, 21 Ne, and 38 Ar are 2.48 Myr for Shergotty, 2.73 Myr for Zagami, and 0.65 Myr for EETA79001 lith. A. Serious loss of radiogenic 4 He due to shock is observed. Cosmogenic neon results for bulk samples from 13 Martian meteorites (new data and literature data) are used in addition to the mineral separates of this study in a new approach to explore evidence of solar cosmic-ray effects. While a contribution of this low-energy irradiation is strongly indicated for all of the shergottites, spallation Ne in Chassigny, Allan Hills (ALH) 84001, and the nakhlites is fully explained by galactic cosmic-ray spallation. Implanted Martian atmospheric gases are present in all mineral separates and the thermal release indicates a near-surface siting. We derive an estimate for the 40 Ar/ 36 Ar ratio of the Martian interior component by subtracting from measured Ar in the (K-poor) pyroxenes the (small) radiogenic component as well as the implanted atmospheric component as indicated from 129 Xe * excesses. Unless compromised by the presence of additional components, a high ratio of ~2000 is indicated for Martian interior argon, similar to that in the Martian atmosphere. Since much lower ratios have been inferred for Chassigny and ALH 84001, the result may indicate spatial and/or temporal variations of 40 Ar/ 36 Ar in the Martian mantle.

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Chronology and petrogenesis of young achondrites, Shergotty, Zagami, and ALHA77005: late magmatism on a geologically active planet

Cited by 228 publications

References 37 publications

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites

Noble gases in mineral separates from three shergottites: Shergotty, Zagami, and EETA79001

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