A gamma-ray spectroscopy survey of Omani meteorites

Weber, Patrick; Hofmann, Beda A.; Tolba, Tamer; Vuilleumier, Jean-Luc (2017). A gamma-ray spectroscopy survey of Omani meteorites. Meteoritics & planetary science, 52(6), pp. 1017-1029. Wiley 10.1111/maps.12847

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The gamma-ray activities of 33 meteorite samples (30 ordinary chondrites, 1 Mars meteorite, 1 iron, 1 howardite) collected during Omani-Swiss meteorite search campaigns 2001–2008 were nondestructively measured using an ultralow background gamma-ray detector. The results provide several types of information: Potassium and thorium concentrations were found to range within typical values for the meteorite types. Similar mean 26Al activities in groups of ordinary chondrites with (1) weathering degrees W0-1 and low 14C terrestrial age and (2) weathering degree W3-4 and high 14C terrestrial age are mostly consistent with activities observed in recent falls. The older group shows no significant depletion in 26Al. Among the least weathered samples, one meteorite (SaU 424) was found to contain detectable 22Na identifying it as a recent fall close to the year 2000. Based on an estimate of the surface area searched, the corresponding fall rate is ~120 events/106 km2*a, consistent with other estimations. Twelve samples from the large JaH 091 strewn field (total mass ~4.5 t) show significant variations of 26Al activities, including the highest values measured, consistent with a meteoroid radius of ~115 cm. Activities of 238U daughter elements demonstrate terrestrial contamination with 226Ra and possible loss of 222Rn. Recent contamination with small amounts of 137Cs is ubiquitous. We conclude that gamma-ray spectroscopy of a selection of meteorites with low degrees of weathering is particularly useful to detect recent falls among meteorites collected in hot deserts.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Hofmann, Beda

Subjects:

500 Science > 520 Astronomy
500 Science > 530 Physics
500 Science > 550 Earth sciences & geology

ISSN:

1086-9379

Publisher:

Wiley

Language:

English

Submitter:

Beda Hofmann

Date Deposited:

02 Nov 2020 08:26

Last Modified:

02 Nov 2020 08:26

Publisher DOI:

10.1111/maps.12847

BORIS DOI:

10.7892/boris.147082

URI:

https://boris.unibe.ch/id/eprint/147082

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