Atmospheric ablation in meteorites: A study based on cosmic ray tracks and neon isotopes

Bhandari, N.; Lal, D.; Rajan, R. S.; Arnold, J. R.; Marti, K.; Moore, C. B.

doi:10.1016/0191-278x(80)90037-2

Cited by 106 publications

(70 citation statements)

References 130 publications

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“…Track densities were measured in mineral grains using standard procedures (Bhandari et al, 1980). Briefly, olivines and pyroxenes (in polished graindsections) were etched for six hours in boiling WN etchant (40% EDTA + 1% oxalic acid and orthophosphoric acid, made to pH 8 by adding NaOH; Krishnaswami et al, 1971) and for one hour in boiling 1:l NaOH, respectively.…”

Section: Particle Track Studiesmentioning

confidence: 99%

Cosmogenic effects in Mbale, L5/6 chondrite

Murty

Bhandari

Suthar

et al. 1998

Meteorit & Planetary Scien

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Abstract-Measurements of particle tracks, cosmogenic radionuclides, and rare gas isotopes in Mbale indicate that the meteoroid had a simple, one-stage exposure for 30.2 Ma in interplanetary space. On the basis of the measured track production rates and 6oCo and 26A1 activities, the meteoroid is estimated to be a sphere with a radius of -36 cm. The activities of several cosmogenic radionuclides (ie., 57C0, 54Mn, 22Na, 44Ti, and 26A1) in two fiagments having different shielding, as estimated by their track density and 6oCo activity, provide the depth variation in their production rates. Cobalt-57,54Mn and 22Na activities agree with the production that is expected around the maximum of the solar cycle 22 as calculated fiom the Sunspot numbers. The U, Th-4He and K-40Ar ages are measured to be 0.54 Ga indicating a late thermal event which is in agreement with the thermal history of some other L group chondrites. The trapped N has d15N of -57 2 4%0, which is much lighter than the average L-group chondrite value; this indicates the presence of an isotopically anomalous light N component.

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Section: Particle Track Studiesmentioning

confidence: 99%

Cosmogenic effects in Mbale, L5/6 chondrite

Murty

Bhandari

Suthar

et al. 1998

Meteorit & Planetary Scien

Self Cite

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“…2 Shielding depths,~X, have been obtained from the production rate vs. shielding depth curves given by Bhandari et al (1980) after raising the observed track density in olivine grains by a factor of 2.…”

Section: Resultsmentioning

confidence: 99%

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 samples were etched in boiling WN etchant of Krishnaswami et al (1971) for 6 h to reveal tracks in olivine grains, but no tracks could be found, setting an upper limit of 10 5 /cm 2 for the track density. Taking the exposure age of 7.4 Ma and following the procedure of Bhandari et al (1980) we estimate that the meteorite has been ablated at least 9 cm on both the locations, consistent with cosmogenic 22 Ne/ 21 Ne ratio.…”

Section: Cosmic-ray Tracksmentioning

confidence: 99%