%0 Journal Article
%T Non-chondritic sulphur isotope composition of the terrestrial mantle
%+ Institut de Physique du Globe de Paris (IPGP)
%A Labidi, J.
%A Cartigny, P.
%A Moreira, M.
%< avec comité de lecture
%@ 0028-0836
%J Nature
%I Nature Publishing Group
%V 501
%P 208-211
%8 2013
%D 2013
%Z 2013Natur.501..208L
%R 10.1038/nature12490
%Z Sciences of the Universe [physics]Journal articles
%X Core-mantle differentiation is the largest event experienced by a growing planet during its early history. Terrestrial core segregation imprinted the residual mantle composition by scavenging siderophile (iron-loving) elements such as tungsten, cobalt and sulphur. Cosmochemical constraints suggest that about 97% of Earth's sulphur should at present reside in the core, which implies that the residual silicate mantle should exhibit fractionated 34S/32S ratios according to the relevant metal-silicate partition coefficients, together with fractionated siderophile element abundances. However, Earth's mantle has long been thought to be both homogeneous and chondritic for 34S/32S, similar to Canyon Diablo troilite, as it is for most siderophile elements. This belief was consistent with a mantle sulphur budget dominated by late-accreted chondritic components. Here we show that the mantle, as sampled by mid-ocean ridge basalts from the south Atlantic ridge, displays heterogeneous 34S/32S ratios, directly correlated to the strontium and neodymium isotope ratios 87Sr/86Sr and 143Nd/144Nd. These isotope trends are compatible with binary mixing between a low-34S/32S ambient mantle and a high-34S/32S recycled component that we infer to be subducted sediments. The depleted end-member is characterized by a significantly negative δ34S of -1.28 +/- 0.33‰ that cannot reach a chondritic value even when surface sulphur (from continents, altered oceanic crust, sediments and oceans) is added. Such a non-chondritic 34S/32S ratio for the silicate Earth could be accounted for by a core-mantle differentiation record in which the core has a 34S/32S ratio slightly higher than that of chondrites (δ34S = +0.07‰). Despite evidence for late-veneer addition of siderophile elements (and therefore sulphur) after core formation, our results imply that the mantle sulphur budget retains fingerprints of core-mantle differentiation.
%G English
%L insu-03581766
%U https://insu.hal.science/insu-03581766
%~ INSU
%~ UNIV-PARIS7
%~ AFRIQ
%~ CNRS
%~ IPGP
%~ SORBONNE-UNIVERSITE
%~ UNIV-PARIS
%~ ALLIANCE-SU