Geochemistry

Core composition gets nebular

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Science  28 Aug 2015:
Vol. 349, Issue 6251, pp. 940-941
DOI: 10.1126/science.349.6251.940-d

Piece of a rare angrite meteorite

PHOTO: JON TAYLOR/FLICKR

The composition of Earth's core is a key piece of evidence needed to determine how and from what sources it was formed. The core is composed mainly of a mixture of iron and nickel but also contains unknown amounts of other elements, including silicon. Dauphas et al. find that the isotopic composition of silicon in a particular class of meteorites called angrites is identical to that of Earth's mantle and probably was inherited from the solar nebula. This unexpected observation suggests that there is less silicon in the core than previously thought, and in general muddies the use of its isotopes to constrain the amount of silicon in planetary cores.

Earth Planet. Sci. Lett. 10.1016/j.epsl.2015.07.008 (2015).

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