A new view of the content of the Earth's core has suggested that there is more oxygen in it than previously believed. Lawrence Livermore geologist Rick Ryerson and international colleagues discovered some new findings about Earth's core and mantle by considering their geophysical and geochemical signatures together. This research provides insight into the origins of Earth's formation.
Based on the higher oxygen concentration of the core, Ryerson's team concludes that Earth must have accreted material that is more oxidised than the present-day mantle, similar to that of planetesimals such as asteroidal bodies. A planetesimal is an object formed from dust, rock and other materials and can be can be anywhere in size from several meters to hundreds of kilometers.
By combining experimental petrology, geochemistry, mineral physics and seismology, the team found that core formation occurred in a hot (liquid) moderately deep magma ocean not exceeding 1,800-kilometer depth, under conditions more oxidised than present-day Earth.
Ryerson noted that this new model is at odds with the current belief that core formation occurred under reduction conditions, instead they found that Earth's magma ocean started out oxidised and has become reduced through time by oxygen incorporation into the core.
They found the oxygen concentrations in the core are higher than previously thought and silicon concentrations are lower than previous estimates.