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In situ cosmogenic Be in olivines and pyroxenes |
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| Authors: | P-H Blard D Bourls R Pik J Lav |
| Institution: | aCentre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement, CNRS-Aix Marseille Université, Aix en Provence, France bCentre de Recherches Pétrographiques et Géochimiques, CNRS, Vandoeuvre-lès-Nancy, France cLaboratoire de Géodynamique des Chaînes Alpines, CNRS-Université Joseph Fourier, Grenoble, France |
| Abstract: | This study proposes an efficient new cleaning procedure for measuring in situ cosmogenic 10Be in olivines and pyroxenes. This chemical routine is specially designed to decontaminate the abundant meteoric 10Be from these minerals. The method was tested on mafic minerals from basaltic flows of Mt. Etna volcano and from Hawaiian flows and moraines. A sequential dissolution test shows that 10Be concentrations decrease with the number of cleaning steps until reaching a constant value. This is a necessary condition to demonstrate the efficiency of the method in properly decontaminating samples of meteoric 10Be. Moreover, cross-calibration with cosmogenic 3He measured within the same samples yielded a sea level high-latitude production rate of 4.5±0.4 at g?1 a?1 for cosmogenic 10Be in mafic minerals. This rate is within 1σ uncertainty of empirically or model-derived rates for 10Be on the same targets. Such concordance supports the consistency of the new method. |
| Keywords: | Cosmogenic Beryllium Helium Olivine Pyroxene Chemical cleaning routine Calibration Lava flows Production rate Mt Etna Mauna Kea |
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