Accretion of the Earth and segregation of its core

  title={Accretion of the Earth and segregation of its core},
  author={Bernard J. Wood and Michael J. Walter and Jon Wade},
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 (> 400 km) molten silicate layer, or ‘magma ocean’, and that conditions became more oxidizing… 

Formation of Earth’s Core

The metal–silicate partitioning of carbon during Earth's accretion and its distribution in the early solar system

Terrestrial Accretion Under Oxidizing Conditions

It is proposed that Earth accreted from materials as oxidized as ordinary or carbonaceous chondrites, as well as moderately siderophile elements (nickel and cobalt), can be produced by core formation under more oxidizing conditions than previously proposed.

The Earth's Lower Mantle and Core

More than 90 percent of the Earth's mass is composed of iron, oxygen, silicon and magnesium, distributed among a metal-rich core, a silicate-rich mantle and more highly fractionated crustal rocks

The redox state of the mantle during and just after core formation

Modelled core–mantle equilibration in a magma ocean that became progressively deeper as accretion proceeded indicates that the mantle would have become gradually oxidized as a result of Si entering the core.

Redox Processes in Early Earth Accretion and in Terrestrial Bodies

The Earth is a unique rocky planet with liquid water at the surface and an oxygen-rich atmosphere, consequences of its particular accretion history. The earliest accreting bodies were small and could

Mechanisms and Geochemical Models of Core Formation

The formation of the Earth's core is a consequence of planetary accretion and processes in the Earth's interior. The mechanical process of planetary differentiation is likely to occur in large, if



Partitioning of oxygen during core formation on the Earth and Mars

Core formation on the Earth and Mars involved the physical separation of metal and silicate, most probably in deep magma oceans, and the FeO extracted may have contributed to chemical heterogeneities in the lowermost mantle, a FeO-rich D″ layer and the light element budget of the core.

Cooling of the Earth and core formation after the giant impact

It is suggested that the Hf–W timescale reflects the principal phase of core-formation before the giant impact, which resulted in late segregation of sulphur-rich metal into which Pb dissolved readily, setting the younger U–Pb age of the Earth.

Determining the composition of the Earth

Material from the Earth, Mars, comets and various meteorites have Mg/Si and Al/Si ratios, oxygen-isotope ratios, osmium-isOTope ratios and D/H, Ar/H2O and Kr/Xe ratios such that no primitive material similar to the Earth's mantle is currently represented in the authors' meteorite collections.

Models of the Earth's Core

Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with

Constitution of the Terrestrial Planets

IN a paper, "On the Constitution of the Terrestrial Planets", by W. H. Ramsey (Mon. Not. Roy. Astro. Soc., 108, 5 ; 1948), it is suggested that the earth' core and mantle are not chemically distinct.