Galactic cosmic ray‐produced <sup>129</sup>Xe and <sup>131</sup>Xe excesses in troilites of the Cape York iron meteorite

Mathew, K. J.; Marti, K.

doi:10.1111/j.1945-5100.2009.tb00721.x

Cited by 12 publications

(27 citation statements)

References 12 publications

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“…131 Xe/ 132 Xe ratios in two other rims and in the platy graphite inclusion are atmospheric. 129* Xe Te / 131* Xe Te in troilite from the Cape York iron meteorite was estimated to be about 4, consistent with the epithermal neutron irradiation (Mathew and Marti 2009). Assuming similar neutron spectra for Campo del Cielo, 131* Xe Te in the San Juan A2 mineral phases analyzed here is expected to be below the detection limit.…”

Section: Xenonsupporting

confidence: 72%

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

Pravdivtseva

Varela

Meshik

et al. 2021

Meteorit & Planetary Scien

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The petrographic study of the San Juan A2 polished section demonstrated textural and compositional similarities with the Campo del Cielo IAB iron meteorite, with trace element abundances in metal following the pattern of bulk Campo del Cielo. Xenon, neon, and helium isotopic compositions have been measured in radial graphite rims, massive graphite inclusions, fine-grained graphite aggregates, cliftonite, and platy graphite. Two silicate inclusions and two areas of metal were also analyzed. 3 He/ 4 He versus 4 He/ 21 Ne data for San Juan metal plot next to the values reported for the El Taco fragment of Campo del Cielo, supporting San Juan being a part of the Campo del Cielo meteorite shower. Based on the Ne isotopic composition of its components, and the observed correlation between 128 Xe and 129 Xe, the San Juan A fragment of Campo del Cielo was well shielded from the primary galactic cosmic ray high-energy irradiation. Its size allowed the secondary neutrons to be fairly well thermalized, receiving an equivalent (normalized to the research reactor with highly thermalized neutron spectrum) fluence of thermal and epithermal neutrons of 6.6 × 10 17 n cm −2 . Considering 1.8 × 10 8 years single-stage and constant exposure geometry irradiation history for Campo del Cielo, and assuming the identical neutron flux spectra for the research reactor and Campo del Cielo, the average thermal equivalent neutron flux for San Juan is about 1.2 × 10 2 n cm −2 s −1 . Xe isotopic composition in the radial graphite rims and platy graphite shows evidence of live 129 I in San Juan and is consistent with a mixture of iodine-derived and tellurium-derived Xe.

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Section: Xenonsupporting

confidence: 72%

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

Pravdivtseva

Varela

Meshik

et al. 2021

Meteorit & Planetary Scien

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“…Niemeyer (1979) determined the Te concentration of 0.5–1.0 ppm in the silicate phase of IAB iron meteorites. Mathew and Marti (2009) obtained 0.99 × 10 −12 cm 3 STP g −1 of epithermal neutron‐produced 129 Xe from Te in troilite D4 of the Cape York iron meteorite; they calculated its CRE age as 82 ± 7 Myr by adopting reported 129 I concentration from Te. The 129 I concentration means that the production rate of 129 Xe from Te by n‐capture is (1.2 ± 0.1) × 10 −14 cm 3 STP g −1 Myr −1 for the D4 troilite.…”

Section: Discussionmentioning

confidence: 99%

⁸¹Kr‐Kr age and multiple cosmic‐ray exposure history of the Vaca Muerta mesosiderite

Bajo¹,

Nagao

2011

Meteorit & Planetary Scien

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Abstract-Noble gas isotopic compositions were measured for a eucritic pebble and bulk material of a silicate-metal mixture from the Vaca Muerta mesosiderite as well as pyroxene and plagioclase separated from the eucritic pebble by total melting and stepwise heating methods. Trapped noble gases were degassed completely by a high-temperature thermal event, probably at the formation of the Vaca Muerta parent body (VMPB). The presence of fissiogenic Xe isotopes from extinct 244 Pu in the bulk samples might be a result of rapid cooling from an early high-temperature metamorphism. High concentrations of cosmogenic noble gases enabled us to determine precise isotopic ratios of cosmogenic Kr and Xe. Spallogenic Ne from Na and unique Ar isotopic compositions were observed. The 81 Kr-Kr exposure age of 168 ± 8 Myr for the silicate pebble is distinctly longer than the age of 139 ± 8 Myr for the bulk samples. The precursor of the pebble had been irradiated on the surface of the VMPB for more than 60 Myr (first stage irradiation), with subsequent incorporation into bulk materials approximately 4 Gyr ago. The Vaca Muerta meteorite was excavated from the VMPB 140 Myr ago (second stage irradiation). Relative diffusion rates among the cosmogenic Ar, Kr, and Xe based on data obtained by stepwise heating indicate that Kr and Xe can be partially retained in pyroxene and plagioclase under the condition that resets the K-Ar system. This result supports the presence of fission Xe and of excess concentration of cosmogenic Kr, which could have survived the thermal event approximately 3.8 Gyr ago.

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“…129 Xe/ 132 Xe ratios show more important variations with a clear excess of radiogenic 129 Xe in all except the final extraction steps that lies close to the atmospheric composition (Table ). These results are consistent with previous reports of Kr and Xe concentrations within troilites from iron meteorites [ Mathew and Marti , ; Nishimura et al ., ]. No significant mass variation was observed following the HF/HCl treatment, but the FeS‐HCl residues displayed a significant gas loss compared to the initial material, both for Kr (≈53%) and Xe (≈38%; Figure and Table ).…”

Section: Resultsmentioning

confidence: 99%

Multiple carriers of Q noble gases in primitive meteorites

Marrocchi

Avice

Estrade

2015

Geophysical Research Letters

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The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. Indirect techniques have revealed that phase Q might be composed of two subphases, one of them associated with sulfide. Here we provide experimental evidence that noble gases trapped within meteoritic sulfides present chemically and thermally driven behavior patterns that are similar to Q gases. We therefore suggest that phase Q is likely composed of two subcomponents: carbonaceous phases and sulfides. In situ decay of iodine at concentration levels consistent with those reported for meteoritic sulfides can reproduce the 129Xe excess observed for Q gases relative to fractionated solar wind. We suggest that the Q‐bearing sulfides formed at high temperature and could have recorded the conditions that prevailed in the chondrule‐forming region(s).

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Galactic cosmic ray‐produced ¹²⁹Xe and ¹³¹Xe excesses in troilites of the Cape York iron meteorite

Cited by 12 publications

References 12 publications

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

⁸¹Kr‐Kr age and multiple cosmic‐ray exposure history of the Vaca Muerta mesosiderite

Multiple carriers of Q noble gases in primitive meteorites

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Galactic cosmic ray‐produced 129Xe and 131Xe excesses in troilites of the Cape York iron meteorite

Cited by 12 publications

References 12 publications

Neutron capture 128Xe and 129Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

Neutron capture 128Xe and 129Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

81Kr‐Kr age and multiple cosmic‐ray exposure history of the Vaca Muerta mesosiderite

Multiple carriers of Q noble gases in primitive meteorites

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Galactic cosmic ray‐produced ¹²⁹Xe and ¹³¹Xe excesses in troilites of the Cape York iron meteorite

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

Neutron capture ¹²⁸Xe and ¹²⁹Xe in the San Juan mass of the Campo del Cielo IAB iron meteorite: Evidence for a high fluence of thermalized neutrons

⁸¹Kr‐Kr age and multiple cosmic‐ray exposure history of the Vaca Muerta mesosiderite