Noble gases in SNC meteorites: Shergotty, Nakhla, Chassigny

Ott, U.

doi:10.1016/0016-7037(88)90017-8

Cited by 151 publications

(204 citation statements)

References 56 publications

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“…Measured 132Xe abundances and 132Xe normalized isotopic ratios are given in Table 2. In ALH84001-b, most (78%) of the radiogenic 129Xe (from extinct 129I) is released at temperatures above 1100oc. The release pattern of radiogenic 129Xe suggests that orthopyroxene is the major carrier of 129Xe, as concluded by Gilmour et al [1998] Chassigny has been reported to contain solar-like trapped Xe [Ott, 1988]. The present Chassigny Xe data (Table 1) …”

Section: Methodssupporting

confidence: 66%

Early evolution of Martian volatiles: Nitrogen and noble gas components in ALH84001 and Chassigny

Mathew¹,

Marti²

2001

J. Geophys. Res.

147

154

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Section: Methodssupporting

confidence: 66%

Early evolution of Martian volatiles: Nitrogen and noble gas components in ALH84001 and Chassigny

Mathew¹,

Marti²

2001

J. Geophys. Res.

147

154

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“…These factors would tend to increase atmospheric 40 Ar/ 36 Ar over time. Further, we note that the Martian atmospheric 129 Xe/ 132 Xe ratio of $2.6 (Bogard et al, 2001) and the Martian interior ratio of $1, as determined in Martian meteorites (Ott, 1988), is just opposite from these atmospheric and interior ratios observed on Earth. Thus radiogenic 129 Xe, like radiogenic 40 Ar, is more concentrated in the Martian atmosphere than in the interior.…”

Section: Validity Of the Ar-ar Agementioning

confidence: 48%

“…Reported trapped ( 40 Ar/ 36 Ar) tr ratios in shergottites range from <100 to almost 3000, all with large uncertainties. Most authors have attributed the lower ratios to a component from the Martian interior (e.g., Ott, 1988;Wiens and Pepin, 1988;Bogard and Garrison, 1998;Mathew and Marti, 2001;Schwenzer et al, 2007;Walton et al, 2007). However, the Martian interior ( 40 Ar/ 36 Ar) MI ratio remains poorly defined.…”

Section: Validity Of the Ar-ar Agementioning

confidence: 99%

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

Nyquist¹,

Bogard²,

Shih³

et al. 2009

Geochimica et Cosmochimica Acta

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Multiple lines of evidence show that the Rb-Sr, Sm-Nd, and Ar-Ar isotopic systems individually give robust crystallization ages for basaltic (or diabasic) shergottite Northwest Africa (NWA) 1460. In contrast to other shergottites, NWA 1460 exhibits minimal evidence of excess 40 Ar, thus allowing an unambiguous determination of its Ar-Ar age. The concordant RbSr, Sm-Nd, and Ar-Ar results for NWA 1460 define its crystallization age to be 346 ± 17 Ma (2r). In combination with petrographic and trace element data for this specimen and paired meteorite NWA 480, these results strongly refute the suggestion by others that the shergottites are $4.1 Ga old. Current crystallization and cosmic-ray exposure (CRE) age data permit identification of a maximum of nine ejection events for Martian meteorites (numbering more than 50 unpaired specimens as of 2008) and plausibly as few as five such events. Although recent high resolution imaging of the Martian surface has identified limited areas of sparsely cratered terrains, the meteorite data suggest that either these areas are representative of larger areas from which the meteorites might come, or that the cratering chronology needs recalibration. Time-averaged 87 Rb/ 86 Sr = 0.16 for the mantle source of the parent magma of NWA 1460/480 over the $4.56 Ga age of the planet is consistent with previously estimated values for bulk silicate Mars in the range 0.13-0.16, and similar to values of $0.18 for the ''lherzolitic" shergottites. Initial e Nd for NWA 1460/480 at 350 ± 16 Ma ago was +10.6 ± 0.5, which implies a time-averaged 147 Sm/ 144 Nd of 0.217 in the Martian mantle prior to mafic melt extraction, similar to values of 0.211-0.216 for the ''lherzolitic" shergottites. These time-averaged values do not imply a simple two-stage mantle/melt evolution, but must result from multiple episodes of melt extractions from the source regions. Much higher ''late-stage" e Nd values for the depleted shergottites imply similar processes carried to a greater degree. Thus, NWA 1460/480, the ''lherzolitic" shergottites and perhaps EET 79001 give the best (albeit imperfect) estimate of the Sr-and Nd-isotopic characteristics of bulk silicate Mars. Published by Elsevier Ltd.

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“…(Ozima and Podosek, 2002) and Martian atmospheres (Mathew et al, 1998). Chassigny is from Ott (1988) and is comparable to SW-Xe (Meshik et al, 2014). Chondritic (Q-Xe) from Busemann et al (2000).…”

Section: Resultsmentioning

confidence: 97%

Noble gases and nitrogen in Tissint reveal the composition of the Mars atmosphere

Avice¹,

Bekaert²,

Aoudjehane³

et al. 2018

Geochem. Persp. Let.

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Comparative planetology is crucial to unravel the origin and evolution of volatile elements on terrestrial planets. We report precise measurements of the elemental and isotopic composition of nitrogen and noble gases in the Martian meteorite Tissint. Ar-N 2 correlations confirm discrepancies between results from Viking and Martian meteorites and those from the Mars Science Laboratory (MSL) mission. The Martian atmospheric 40 Ar/ 36 Ar ratio is estimated to be 1714 ± 170 (1σ), lower than the value determined by Viking but in agreement with, and with higher precision than, data from MSL. We confirm a solar wind-like origin for Martian Kr and Xe. Excesses on light Kr isotopes are lower than those measured by MSL. Cosmogenic excesses in the Xe isotopic spectrum could have been produced in space during exposure of the Tissint parent body to cosmic rays.

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Noble gases in SNC meteorites: Shergotty, Nakhla, Chassigny

Cited by 151 publications

References 56 publications

Early evolution of Martian volatiles: Nitrogen and noble gas components in ALH84001 and Chassigny

Early evolution of Martian volatiles: Nitrogen and noble gas components in ALH84001 and Chassigny

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

Noble gases and nitrogen in Tissint reveal the composition of the Mars atmosphere

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