Neon produced by solar cosmic rays in ordinary chondrites

Roth, Antoine S. G.; Trappitsch, Reto; Metzler, Knut; Hofmann, Beda A.; Leya, Ingo (2017). Neon produced by solar cosmic rays in ordinary chondrites. Meteoritics & planetary science, 52(6), pp. 1155-1172. Meteoritical Society at the University of Arkansas, Dept. of Chemistry and Biochemistry 10.1111/maps.12868

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Solar-cosmic-ray-produced Ne (SCR-Ne), in the form of low cosmogenic ²¹Ne/²²Ne ratios (²¹Ne/²²Necos <0.8), is more likely to be found in rare meteorite classes, like Martian meteorites, than in ordinary chondrites. This may be the result of a sampling bias: SCR-Ne is better preserved in meteorites with small preatmospheric radii and these specimens are often only studied if they belong to unusual or rare classes. We measured He and Ne isotopic concentrations and nuclear tracks in 25 small unpaired ordinary chondrites from Oman. Most chondrites have been intensively heated during atmospheric entry as evidenced by the disturbed track records, the low ³He/²¹Ne ratios, the low 4He concentrations, and the high peak release temperatures. Concentration depth profiles indicate significant degassing; however, the Ne isotopes are mainly undisturbed. Remarkably, six chondrites have low ²¹Ne/²²Necos in the range 0.711–0.805. Using a new physical model for the calculation of SCR production rates, we show that four of the chondrites contain up to ~20% of SCR-Ne; they are analyzed in terms of preatmospheric sizes, cosmic ray exposure ages, mass ablation losses, and orbits. We conclude that SCR-Ne is preserved, regardless of the meteorite class, in specimens with small preatmospheric radii. Sampling bias explains the predominance of SCR-Ne in rare meteorites, although we cannot exclude that SCR-Ne is more common in Martian meteorites than it is in small ordinary chondrites.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Leya, Ingo

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

1086-9379

Publisher:

Meteoritical Society at the University of Arkansas, Dept. of Chemistry and Biochemistry

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

08 Dec 2017 14:26

Last Modified:

08 Dec 2017 14:26

Publisher DOI:

10.1111/maps.12868

BORIS DOI:

10.7892/boris.106972

URI:

https://boris.unibe.ch/id/eprint/106972

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