¹J.A. Barrat,²O. Rouxel,³K. Wang,^4,5F. Moynier,^6,7A. Yamaguchi,⁸A. Bischoff,⁹J. Langlade
¹Université de Bretagne Occidentale, Institut Universitaire Européen de la Mer, CNRS UMR 6538, Place Nicolas Copernic, 29280 Plouzané, France
²IFREMER, centre de Brest, 29280 Plouzané, France
³Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
⁴Institut de Physique du Globe de Paris, Institut Universitaire de France, Université Paris Diderot, Sorbonne Paris Cité, 1 rue Jussieu, 75238 Paris Cedex 05, France
⁵Institut Universitaire de France, Paris, France
⁶National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
⁷Department of Polar Science, School of Multidisciplinary Science, Graduate University for Advanced Sciences, Tachikawa, Tokyo 190-8518, Japan
⁸Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
⁹CNRS UMS 3113, I.U.E.M., Place Nicolas Copernic, 29280 Plouzané Cedex, France

Ureilite meteorites are achondrites that are debris of the mantle of a now disrupted differentiated asteroid rich in carbon. They provide a unique opportunity to study the differentiation processes of such a body. We analyzed the iron isotopic compositions of 30 samples from the Ureilite Parent Body (UPB) including 29 unbrecciated ureilites and one ureilitic trachyandesite (ALM-A) which is at present the sole large crustal sample of the UPB. The δ56Fe of the whole rocks fall within a restricted range, from 0.01 to 0.11‰, with an average of +0.056±0.008‰+0.056±0.008‰, which is significantly higher than that of chondrites. We show that this difference can be ascribed to the segregation of S-rich metallic melts at low degrees of melting at a temperature close to the Fe–FeS eutectic, and certainly before the onset of the melting of the silicates (View the MathML source<1100°C), in agreement with the marked S depletions, and the siderophile element abundances of the ureilites. These results point to an efficient segregation of S-rich metallic melts during the differentiation of small terrestrial bodies.

Reference
Barrat JA, Rouxel O,Wang K, Moynier F,Yamaguchi A,Bischoff A, Langlade J (2015) Early stages of core segregation recorded by Fe isotopes in an asteroidal mantle. Earth and Planetary Science Letters, 419, 93–100
Link to Article [http://dx.doi.org/10.1016/j.epsl.2015.03.026]

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