Early stages of core segregation recorded by Fe isotopes in an asteroidal mantle

Type Article
Date 2015-06
Language English
Author(s) Barrat Jean-Alix1, Rouxel OlivierORCID2, Wang K.3, Moynier F.4, 5, Yamaguchi A.6, 7, Bischoff A.8, Langlade Jessica9
Affiliation(s) 1 : Univ Bretagne Occidentale, CNRS, UMR 6538, Inst Univ Europeen Mer, F-29280 Plouzane, France.
2 : IFREMER, Ctr Brest, F-29280 Plouzane, France.
3 : Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA.
4 : Univ Paris Diderot, Inst Univ France, Inst Phys Globe Paris, Sorbonne Paris Cite, F-75238 Paris 05, France.
5 : Inst Univ France, Paris, France.
6 : Natl Inst Polar Res, Tachikawa, Tokyo 1908518, Japan.
7 : Grad Univ Adv Sci, Sch Multidisciplinary Sci, Dept Polar Sci, Tachikawa, Tokyo 1908518, Japan.
8 : Univ Munster, Inst Planetol, D-48149 Munster, Germany.
9 : CNRS, UMS 3113, IUEM, F-29280 Plouzane, France.
Source Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2015-06 , Vol. 419 , P. 93-100
DOI 10.1016/j.epsl.2015.03.026
WOS© Times Cited 41
Keyword(s) iron isotopes, achondrite, ureilite, core
Abstract 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.
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