¹Boris Laurent, ¹Mathieu Roskosz, ²Laurent Remusat, ²François Robert, ¹Hugues Leroux,³Hervé Vezin, ¹Christophe Depecker, ⁴Nicolas Nuns, ¹Jean-Marc Lefebvre
¹UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d’Ascq F-59655, France
²IMPMC, CNRS UMR 7590, Sorbonne Universités, Université Pierre et Marie Curie, IRD, Muséum National d’Histoire Naturelle, CP 52, 57 rue Cuvier, Paris 75231
³LASIR, Université de Lille 1, CNRS UMR 8516, Villeneuve d’Ascq F-59655,
⁴Institut M.E. Chevreul, Université de Lille 1, CNRS, FR 2638, Villeneuve d’Ascq F-59655,

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Reference
Laurent B, Roskosz M, Remusat L, Robert F, Leroux H, Vezin H, Depecker C, Nuns N, Lefebvre J-M (2015) The deuterium/hydrogen distribution in chondritic organic matter attests to early ionizing Irradiation. Nature Communications 6, 8567
Link to Article [doi:10.1038/ncomms9567]

^1,2C. Defouilloy, ¹P. Cartigny, ¹N. Assayag, ^3,4F. Moynier, ⁵J.-A. Barrat
¹Géochimie des Isotopes Stables, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris, France
²Laboratoire de Minéralogie et Cosmochimie du Muséum, Muséum National d’Histoire Naturelle, Paris, UMR 7202, 61 rue Buffon, 75005 Paris, France
³Cosmochimie, Astrophysique et Géophysique Expérimentale, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris, France
⁴Institut Universitaire de France, Paris, France
⁵U.B.O.-I.U.E.M., CNRS UMR 66538 (Domaines Océaniques), Place Nicolas Copernic, 29280 Plouzané Cedex, France

In order to better understand the formation and evolution of their parent bodies, the three isotope ratios of sulfur were analyzed in 33 enstatite meteorites (24 enstatite chondrites and 9 aubrites). The results show that on average all enstatite chondrite groups are enriched in the lightest isotopes compared to other chondrite groups, with means of δ34S of -0.28 ± 0.22 ‰ for EH3/4, -0.16 ± 0.16 ‰ for EH5, -0.32 ± 0.15 ‰ for EL3, -0.67 ± 0.16 ‰ for EL6 and -0.64 ± 0.00 ‰ for EL7 (all 1σ). Aubrites show a larger isotope variability in their composition, with a δ34S varying from -1.350‰ to +0.154 ‰. Contrary to previously published results, our data show a distinct composition for EL6 compared to other enstatite chondrites. This could be related to an impact-induced loss of isotopically heavy oldhamite (δ34S = by 3.62 ± 3.02 ‰ (1σ)) on the EL parent body. Although the bulk sulfur in both enstatite meteorites and aubrites does not show any significant Δ33S and Δ36S, the oldhamite fraction shows clear evidence of mass independent fractionation on the 36S/32S ratio (in 3 out of 9 analyzes, Δ36S up to +2.2‰), a signal that is not correlated to any 33S/32S anomaly (in 1 out of 9 analyzes, Δ33S down to -0.085‰). Though a nebular or photochemical origin cannot be ruled out, the most plausible mechanism to produce such isolated non-mass dependent 36S/32S anomalies would be a contribution of FeCl2 containing excesses of 36S due to the decay of 36Cl to the leached oldhamite fraction. Even though the sulfur isotopic composition measured in enstatite meteorites is distinct from the Bulk Silicate Earth (BSE), the isotopically lightest samples of EL6, EL7 and aubrites are approaching the isotopic composition of the BSE and enstatite meteorites remain the meteorites with the sulfur isotopic composition the closest to the terrestrial one.

Reference
Defouilloy C, Cartigny P, Assayag N, Moynier F, Barrat J-A (2015) High-precision sulfur isotope composition of enstatite meteorites and implications of the formation and evolution of their parent bodies. Geochimica et Cosmochimica Acta (in Press)
Link to Article [doi:10.1016/j.gca.2015.10.009]
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