Light noble gases and cosmogenic radionuclides in Estherville, Budulan and other mesosiderites: Implications for exposure histories and production rates

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dc.contributor.authorAlbrecht, Aen_AU
dc.contributor.authorSchnabel, Cen_AU
dc.contributor.authorVogt, Sen_AU
dc.contributor.authorXue, Sen_AU
dc.contributor.authorHerzog, GFen_AU
dc.contributor.authorBegemann, Fen_AU
dc.contributor.authorWeber, Hen_AU
dc.contributor.authorMiddleton, Ren_AU
dc.contributor.authorFink, Den_AU
dc.contributor.authorKlein, Jen_AU
dc.date.accessioned2021-12-21T01:09:59Zen_AU
dc.date.available2021-12-21T01:09:59Zen_AU
dc.date.issued2000-08en_AU
dc.date.statistics2021-11-02en_AU
dc.description.abstractWe report measurements of 26AI, 10Be, 41Ca, and 36Cl in the silicate and metal phases of 11 mesosiderites, including several specimens each of Budulan and Estherville, of the brecciated meteorite Bencubbin, and of the iron meteorite Udei Station. Average production rate ratios (atom/atom) for metal phase samples from Estherville and Budulan are 26Al/10Be = 0.77 ± 0.02; 36Cl/10Be = 5.3 ± 0.2. For a larger set of meteorites that includes iron meteorites and other mesosiderites, we find 26Al/10Be = 0.72 ± 0.01 and 36Cl/10Be = 4.5 ± 0.2. The average 41Ca/36Cl production rate ratio is 1.10 ± 0.04 for metal separates from Estherville and four small iron falls. The 41Ca activities in dpm/(kg Ca) of various silicate separates from Budulan and Estherville span nearly a factor of 4, from <400 to >1600, indicating preatmospheric radii of >30 cm. After allowance for composition, the activities of 26Al and 10Be (dpm/kg silicate) are similar to values measured in most ordinary chondrites and appear to depend only weakly on bulk Fe content. Unless shielding effects are larger than suggested by the 36Cl and 41Ca activities of the metal phases, matrix effects are unimportant for 10Be and minor for 26Al. Noble gas concentrations and isotopic abundances are reported for samples of Barea, Emery, Mincy, Morristown, and Marjalahti. New estimates of 36Cl/36Ar exposure ages for the metal phases agree well with published values. Neon-21 production rates for mesosiderite silicates calculated from these ages and from measured 21Ne contents are consistently higher than predicted for L chondrites despite the fact that the mesosiderite silicates have lower Mg contents than L chondrites. We suggest that the elevation of the 21Ne production rate in mesosiderite silicates reflects a “matrix effect,” that is, the influence of the higher Fe content of mesosiderites, which acts to enhance the flux of low-energy secondary particles and hence the 21Ne production from Mg. As 10Be production is relatively insensitive to this matrix effect, 10Be/21Ne ages give erroneously low production rates and high exposure ages. By coincidence, standard 22Ne/21Ne based “shielding” corrections give fairly reliable 21Ne production rates in the mesosiderite silicates. © 1999-2021 John Wiley & Sons, Inc.en_AU
dc.identifier.citationAlbrecht, A., Schnabel, C., Vogt, S., Xue, S., Herzog, G. F., Begemann, F., Weber, H., Middleton, R., Fink, D., & Klein, J. (2000). Light noble gases and cosmogenic radionuclides in Estherville, Budulan and other mesosiderites: Implications for exposure histories and production rates. Meteoritics & Planetary Science, 35(5), 975-986. doi:10.1111/j.1945-5100.2000.tb01486.xen_AU
dc.identifier.issn1945-5100en_AU
dc.identifier.issue5en_AU
dc.identifier.journaltitleMeteoritics & Planetary Scienceen_AU
dc.identifier.pagination975-986en_AU
dc.identifier.urihttps://doi.org/10.1111/j.1945-5100.2000.tb01486.xen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12609en_AU
dc.identifier.volume35en_AU
dc.language.isoenen_AU
dc.publisherWileyen_AU
dc.subjectMeteoritesen_AU
dc.subjectIron meteoritesen_AU
dc.subjectSilicatesen_AU
dc.subjectChondritesen_AU
dc.subjectRare gasesen_AU
dc.subjectRadioisotopesen_AU
dc.titleLight noble gases and cosmogenic radionuclides in Estherville, Budulan and other mesosiderites: Implications for exposure histories and production ratesen_AU
dc.typeJournal Articleen_AU
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