Accretion of the Earth and segregation of its core
Abstract
The Earth took 30-40 million years to accrete from smaller `planetesimals'. Many of these planetesimals had metallic iron cores and during growth of the Earth this metal re-equilibrated with the Earth's silicate mantle, extracting siderophile (`iron-loving') elements into the Earth's iron-rich core. The current composition of the mantle indicates that much of the re-equilibration took place in a deep (> 400km) molten silicate layer, or `magma ocean', and that conditions became more oxidizing with time as the Earth grew. The high-pressure nature of the core-forming process led to the Earth's core being richer in low-atomic-number elements, notably silicon and possibly oxygen, than the cores of the smaller planetesimal building blocks.
- Publication:
-
Nature
- Pub Date:
- June 2006
- DOI:
- 10.1038/nature04763
- Bibcode:
- 2006Natur.441..825W