Rare gases and 36Cl in stony-iron meteorites: cosmogenic elemental production rates, exposure ages, diffusion losses and thermal histories

Begemann, F.; Weber, H. W.; Vilcsek, E.; Hintenberger, H.

doi:10.1016/0016-7037(76)90213-1

Cited by 113 publications

(91 citation statements)

References 37 publications

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“…The more cosmogenically rich sample-fractions are plotted in Fig. 1 and agree well with the range of observed composi tions for the silicates examined by BEGEMANN et al (1976). Their data show that the amount of metal is lower than from silicates, in agree ment with the low spallation cross sections for Fe in meteorites (MUNK, 1967).…”

Section: Resultssupporting

confidence: 73%

“…This He loss was noticed over a decade ago by MEGRUE (1966) and was recently confirmed by BEGEMANN et al (1976) and by our results, listed in Table 1. 3He results are thus of little value in defining CREA's.…”

Section: Resultssupporting

confidence: 71%

“…21Ne/22Ne ratios for Hainholtz, Crab Orchard, and a few other samples (BEGEMANN et al, 1976) including Bondoc, extend to values near 1.00, which, according to CRESSY and BOGARD's extrapola tion of shielding effects, indicate pre-atmo spheric masses > 500 kg. Bondoc, at least, with a pre-atmospheric mass > 6,000 kg, approximat ed by CRESSY and SHEDLOVSKY (1965) from a study of shielding effects on the cosmic ray production of several long lived radioactive nuclides, provides justification for this inter pretation.…”

Section: Resultsmentioning

confidence: 96%

“…BEGEMANN et al (1976) studied meteorites have lost much of the volatile com separated metal and stone phases of thirteen ponent trapped during condensation of the solar mesosiderites in which they measured cosmo system, including the primordial noble gases. genic production rates and CREA's.…”

Section: Introductionmentioning

confidence: 99%

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He, Ne and Ar in four mesosiderites and the Binda achondrite.

Edgerley

Rowe

1979

Geochem. J.

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The 21Ne/22Ne ratio showed a variation between 0.83 and 1.00 indicating a definite dependence on the combined effects of target element abundances and cosmic ray shielding. The shielding effect seems to be especially pronounced in the mesosiderites.The 36Ar/38Ar ratio for spallation was found to be -0.65 in agreement with previous work. Cosmic ray exposure ages determined from cosmogenic Ar abundances fall in the range 40 to 87myr for mesosiderites. Crab Orchard gave a K-Ar age of 3.2 X 109yr. The Binda achondrite gave 44myr and 3.2 X 109yr respectively for cosmic ray exposure and K-Ar ages.

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Section: Resultssupporting

confidence: 73%

Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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He, Ne and Ar in four mesosiderites and the Binda achondrite.

Edgerley

Rowe

1979

Geochem. J.

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“…The 36 Cl concentrations in the (leached) stone fractions range from 5.3 to 6.9 dpm/kg, with an average concentration of 6.2 ± 0.5 dpm/kg. When normalized to the main target elements for spallation, assuming P( 36 Cl) Ca /P( 36 Cl) Fe = 10 (Begemann et al 1976) and P( 36 Cl) K /P( 36 Cl) Ca = 2 (plus some minor contributions from Mn, Cr and Ti), we find an average 36 Cl concentration of 19.0 ± 1.3 dpm/kg[Fe + 10Ca + 20K] or 19.8 ± 1.4 dpm/kg[Fe + 10Ca + 20K] at the time of fall, which is consistent with typical spallation produced 36 Cl concentrations in stone meteorites. The lack of correlation of 36 Cl with neutron-capture 41 Ca in the leached silicates simply indicates that neutron-capture 36 Cl was effectively removed by the leaching procedure.…”

Section: Radionuclidesmentioning

confidence: 99%

The complex exposure history of the Jiddat al Harasis 073 L‐chondrite shower

Huber

Gnos

Hofmann

et al. 2008

Meteorit & Planetary Scien

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36 Ar is predominantly released between 1000-1200 °C. All these results are consistent with a first-stage exposure of ~65 Ma within ~20 cm of the surface of the L-chondrite parent body, followed by ejection of a 1.5-2 m large object, which was then delivered to Earth within about 0.5 and 0.7 Ma. The cosmogenic nuclide data in JaH 073 thus corroborate the trend that many of the large chondrites studied so far experienced a complex exposure history. The observed 3 He/ 21 Ne ratios of 2.5-3.0 in the most shielded samples (including those of the main mass) are lower than predicted by model calculations, but similar to the lowest values found in the large Gold Basin L-chondrite shower. The Bern plot, which gives a linear correlation for 3 He/ 21 Ne versus 22 Ne/ 21 Ne, is evidently not valid for very high shielding. Some of our measured 22 Ne/ 21 Ne ratios in JaH 073 are lower than 1.06, which is not well understood, but might be explained by loss of cosmogenic neon from shocked sodium-rich plagioclase during terrestrial weathering. The amount of trapped atmospheric argon in the JaH 073 fragments varies by almost two orders of magnitude and shows only a weak correlation with the size of the fragments, which range from <100 g to >50 kg. Finally, low concentrations of radiogenic 4 He and 40 Ar indicate incomplete degassing <1 Ga ago, probably at the main collision event on the L-chondrite parent body ~480 Ma ago.

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Meteorites (36Cl)

Welten¹

2015

Encyclopedia of Marine Geosciences

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Rare gases and 36Cl in stony-iron meteorites: cosmogenic elemental production rates, exposure ages, diffusion losses and thermal histories

Cited by 113 publications

References 37 publications

He, Ne and Ar in four mesosiderites and the Binda achondrite.

He, Ne and Ar in four mesosiderites and the Binda achondrite.

The complex exposure history of the Jiddat al Harasis 073 L‐chondrite shower

Meteorites (36Cl)

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