Abstract
Highly siderophile elements (HSEs) are strongly depleted in the bulk silicate Earth (BSE) but are present in near-chondritic relative abundances. The conventional explanation is that the HSEs were stripped fromthe mantle by the segregation of metal during core formation but were added back in near-chondritic proportions by late accretion, after core formation had ceased. Here we show that metal-silicate equilibration and segregation during Earth's core formation actually increased HSE mantle concentrations because HSE partition coefficients are relatively low at the high pressures of core formation within Earth. The pervasive exsolution and segregation of iron sulfide liquid from silicate liquid (the "Hadean matte") stripped magma oceans of HSEs during cooling and crystallization, before late accretion, and resulted in slightly suprachondritic palladium/iridium and ruthenium/iridium ratios.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1141-1144 |
| Number of pages | 4 |
| Journal | Science |
| Volume | 353 |
| Issue number | 6304 |
| DOIs | |
| State | Published - Sep 9 2016 |
Funding
D.C.R., V.L., S.A.J., A.M., and H.P. were supported by the European Research Council Advanced Grant ACCRETE (Accretion and Early Differentiation of the Earth and Terrestrial Planets; contract number 290568). A.K.V. was supported by the German Science Foundation (DFG) Priority Programme SPP1385, "The first 10 million years of the solar system - a planetary materials approach" (grant Ru1323/2). We thank H. J. Melosh and R. J. Walker for discussions and three reviewers for their helpful and constructive comments. Data files with final results are available in the supplementary materials.
ASJC Scopus subject areas
- General