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Relative chronology of crust formation on asteroid Vesta: Insights from the geochemistry of diogenites |
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| Authors: | Jean-Alix Barrat Akira Yamaguchi Claire Bollinger Marcel Bohn |
| Institution: | a Université Européenne de Bretagne, France b Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, 29280 Plouzané Cedex, France c Antarctic Meteorite Research Center, National Institute of Polar Research, 10-3 Midoricho, Tachikawa, Tokyo 190-8518, Japan d Laboratoire de Minéralogie et de Cosmochimie du Muséum, CNRS UMR 7202, Muséum National d’Histoire Naturelle, CP52, 57 rue Cuvier, 75005 Paris, France |
| Abstract: | The eucrites and diogenites are meteorites that probably originate from asteroid 4-Vesta. The upper part of the crust of this body is certainly composed of eucrites which are basaltic or gabbroic rocks. Diogenites are ultramafic cumulates whose relationships with eucritic lithologies are unknown. Here, we show that the orthopyroxenes of some diogenites display very deep negative Eu anomalies (Eu/Eu∗ close to 0.1 or lower). The contamination of the parental magmas of diogenites by melts derived by partial melting of the eucritic crust can satisfactorily explain the range of the Eu anomalies displayed by diogenites. Thus, these anomalies are the first firm indication that parental melts of diogenites have intruded the eucritic crust, and consequently are younger than eucrites. |
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