Nitrogen isotopic compositions of iron meteorites

Prombo, C. A.; Clayton, Robert N.

doi:10.1016/0016-7037(93)90153-n

Cited by 52 publications

(46 citation statements)

References 42 publications

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“…The high-temperature Xe ratios might therefore link a N carrier to troilite. In fact, Prombo and Clayton (1993) measured the bulk N signature of troilite (δ 15 N = −73.2‰ ± 0.4‰) from Canyon Diablo, which is consistent with this signature. However, the large sample of troilite used in that study may have also been affected by inclusions in the troilite.…”

Section: A Multicomponent Modelsupporting

confidence: 58%

“…This problem is ubiquitous for these irons. Prombo and Clayton (1993) (Table 1). Similarly, our total N values for the two samples of Balfour Downs (IAB) (−53.9‰ and −25.9‰) and the two samples of Bischtübe (IAB) (−31.4‰ and −50.8‰) do not overlap.…”

Section: Resultsmentioning

confidence: 99%

“…Prombo and Clayton (1993) and Franchi et al (1993) used one-step extractions of the bulk metal and reported averages of distinct signatures. Bulk extraction has a limitation if there is more than one N reservoir present in the metal samples.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, Franchi et al (1993) studied acid residues consisting of minor phases of IAB and other irons using stepped combustion and found N isotopic ratios close to the bulk values for these meteorites. Prombo and Clayton (1993) measured very light nitrogen (δ 15 N = −73.2‰) from the troilite of Canyon Diablo. Nitrides can be present in iron meteorites, as Buchwald and Scott (1971) reported the presence of carlsbergite in iron meteorites.…”

Section: Introductionmentioning

confidence: 99%

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Nitrogen components in IAB/IIICD iron meteorites

Ponganis

Marti

2007

Meteorit & Planetary Scien

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Abstract-Isotopic variations have been reported for many elements in iron meteorites, with distinct N signatures found in the metal and graphite of IAB irons. In this study, a dozen IAB/IIICD iron meteorites (see Table 1 for new classifications) were analyzed by stepwise pyrolysis to resolve nitrogen components. Although isotopic heterogeneity has been presumed to be lost in thermally processed parent objects, the high-resolution nitrogen isotopic data indicate otherwise. At least one reservoir has a light nitrogen signature, δ 15 N = −(74 ± 2)‰, at 900 °C to 1000 °C, with a possible second, even lighter, reservoir in Copiapo (δ 15 N ≤ −82‰). These releases are consistent with metal nitride decomposition or low-temperature metal phase changes. Heavier nitrogen reservoirs are observed in steps ≤700 °C and at 1200 °C to 1400 °C. The latter release has a δ 15 N signature with a limit of ≥−16‰. Xenon isotopic signatures are sensitive indicators for the presence of inclusions because of the very low abundances of Xe in metal. The combined high-temperature release shows 131 Xe and 129 Xe excesses to be consistent with shifts expected for Te(n,γ) reaction in troilite by epithermal neutrons, but there are also possible alterations in the isotopic ratios likely due to extinct 129 I and cosmic-ray spallation.The IAB/IIICD iron data imply that at least one light N component survived the formation processes of iron parent objects which only partially exchanged nitrogen between phases. Preservation of separate N reservoirs conflicts with neither the model of impact-heating effects for these meteorites nor reported age differences between metal and silicates.

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Section: A Multicomponent Modelsupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nitrogen components in IAB/IIICD iron meteorites

Ponganis

Marti

2007

Meteorit & Planetary Scien

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“…An important conclusion is that there is a large isotopic difference between solar nitrogen and terrestrial nitrogen (δ 15 N = 0‰), an issue to which we will return later. Following our lunar nitrogen studies, a series of graduate students measured nitrogen isotopes in increasingly difficult samples: stony meteorites (Kung & Clayton 1978), iron meteorites (Prombo & Clayton 1993), terrestrial crustal rocks (Zhang 1988), and terrestrial mantle rocks (Huang 1997 …”

Section: Extraterrestrial Isotopesmentioning

confidence: 99%