Cosmogenic Radionuclides and Noble Gases in the Wethersfield (1982) Chondrite

Evans, J. C.; Reeves, J. H.; Bogard, D. D.

doi:10.1111/j.1945-5100.1986.tb00868.x

Cited by 11 publications

(3 citation statements)

References 7 publications

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“…Our CRE age of Dhajala bulk is 4.95 ± 0.95 Ma (Fig. 6), which is similar to earlier reports (e.g., Evans et al 1986;Eugster et al 2007). The bulk sample and all the chondrules of the present study come from a single chip of <2 g and hence both bulk and chondrules experienced the same shielding and post-compaction irradiation record.…”

Section: Dhajalasupporting

confidence: 91%

Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

Das

Murty

2009

Meteorit & Planetary Scien

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Section: Dhajalasupporting

confidence: 91%

Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

Das

Murty

2009

Meteorit & Planetary Scien

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“…Concentrations in Gujargaon are about a factor of 2.1-2.8 lower. However, the latter are similar to values of 64.6 ± 1.6 dpm/kg for 22Na and 48 ± I dpm/kg for 54Mn observed in the Wethersfield meteorite that fell in 1982 (Evans et al, 1986). The ratio 22Naj26Al is 1.34 in Gujargaon and 1.17 in Wethersfield compared to 2.2 to 2.6 observed in various fragments of Dhajala (Table 4).…”

Section: Resultssupporting

confidence: 80%

Untitled

1988

Meteoritics

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Abstract-Cosmic ray produced tracks, He and Ne isotopes and radionuclides have been studied in the recently fallen H5 chondrite Gujargaon. The results indicate an exposure age of about 7 Ma. The high track production rates of 0.25 to 0.69 x 10 6 cm? Ma-' suggest that the Gujargaon meteoroid had a small size (RE = 9-10 ern) in space and suffered 1-3 em ablation in the atmosphere. The conclusion about the meteoroid size is supported by the low activity of neutron capture isotope 60CO and high spallogenic 22NePINe ratio of about 1.25. The data on long lived isotopes lOBe, S3Mn and 26AI are used to derive production rates of these isotopes in a rock having a radius of 9 em and the activity levels of the short lived isotopes 22Na and 54Mn are used to estimate the effect of modulation of galactic cosmic rays at the time of solar maximum of 1982.

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“…The GCR are composed primarily of high-energy protons and He-nuclei, and the SCR are represented mostly by protons with energies below 1 GeV. The cosmogenic radionuclides have been widely used to study the origin, cosmic-ray exposure ages, and orbital history of meteorites (e.g., Lal 1972;Nishiizumi et al 1979;Honda et al 1982;Reedy et al 1983;Evans et al 1986;Povinec 1987;Lavrukhina and Ustinova 1990;Bhandari et al 1994Bhandari et al , 2002Herzog 2005;Welten et al 2011). When cosmic-ray particles interact with cosmic objects, they leave tracks in their minerals and produce cascades of particles, which lead to the production of radioactive and stable nuclides in the target material.…”

Section: Cosmogenic Radionuclides In Meteoritesmentioning

confidence: 99%

Cosmogenic radionuclides and mineralogical properties of the Chelyabinsk (LL5) meteorite: What do we learn about the meteoroid?

Povinec

Laubenstein

Jull

et al. 2015

Meteorit & Planetary Scien

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On February 15, 2013, after the observation of a brilliant fireball and a spectacular airburst over the southern Ural region (Russia), thousands of stones fell and were rapidly recovered, bringing some extremely fresh material for scientific investigations. We undertook a multidisciplinary study of a dozen stones of the Chelyabinsk meteorite, including petrographic and microprobe investigations to unravel intrinsic characteristics of this meteorite. We also study the short and long‐lived cosmogenic radionuclides to characterize the initial meteoroid size and exposure age. Petrographic observations, as well as the mineral compositions obtained by electron microprobe analyses, allow us to confirm the classification of the Chelyabinsk meteorite as an LL5 chondrite. The fragments studied, a few of which are impact melt rocks, contain abundant shock melt veins and melt pockets. It is likely that the catastrophic explosion and fragmentation of the Chelyabinsk meteoroid into thousands of stones was in part determined by the initial state of the meteoroid. The radionuclide results obtained show a wide range of concentrations of 14C, 22Na, 26Al, 54Mn, 57Co, 58Co, and 60Co, which indicate that the pre‐atmospheric object had a radius >5 m, consistent with other size estimates based on the magnitude of the airburst caused by the atmospheric entry and breakup of the Chelyabinsk meteoroid. Considering the observed 26Al activities of the investigated samples, Monte Carlo simulations, and taking into account the 26Al half‐life (0.717 Myr), the cosmic‐ray exposure age of the Chelyabinsk meteorite is estimated to be 1.2 ± 0.2 Myr. In contrast to the other radionuclides, 14C showed a very large range only consistent with most samples having been exposed to anthropogenic sources of 14C, which we associate with radioactive contamination of the Chelyabinsk region by past nuclear accidents and waste disposal, which has also been confirmed by elevated levels of anthropogenic 137Cs and primordial 40K in some of the Chelyabinsk fragments.

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Cosmogenic Radionuclides and Noble Gases in the Wethersfield (1982) Chondrite

Cited by 11 publications

References 7 publications

Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

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Cosmogenic radionuclides and mineralogical properties of the Chelyabinsk (LL5) meteorite: What do we learn about the meteoroid?

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