Community Research and Development Information Service - CORDIS

ERC

DECore Result In Brief

Project reference: 207467
Funded under: FP7-IDEAS-ERC
Country: France

Geophysics reveals how the Earth’s core was formed

Formation of the Earth’s core and the processes involved are not yet clearly understood. This gap in scientific knowledge was addressed by an EU-funded initiative, which developed experimental procedures to study the processes that occurred within the Earth during the first 100 million years after the formation of the Solar System.
Geophysics reveals how the Earth’s core was formed
The aim of the DECORE (Deep Earth chemistry of the core) project was to investigate the accretion of the Earth and its primordial differentiation and formation of its core. It studied how accretionary material comprising rocks and iron-rich metal melted and separated out the metallic portion from the rocky portion to form the core and the silicate mantle (magma ocean) respectively.

Researchers followed the evolution of siderophile trace elements and light atomic elements incorporation into the core, and how they were linked. This was because siderophile trace-element concentrations in the mantle and light-element concentration in the core can be measured through geochemistry and geophysics to provide major insights into core formation.

Scientists used high-pressure, high-temperature apparatus involving large-volume presses and laser heated anvil cells to reproduce the conditions found deep in the Earth. Results indicated that core formation in a relatively oxidized proto-Earth was viable. Silicon was the first major element entering the core, while the second was mostly oxygen with small amounts of silicon.

The scenario of core formation in an oxidised magma ocean that becomes reduced over time provided a viable mechanism for explaining the reduction of the magma ocean through the incorporation of oxygen in the core. It also provided a better explanation of the partitioning of the elements chromium (Cr) and vanadium (V).

From a geophysical point of view project calculations showed that oxygen was the only element that is always required in the outer core, to match its seismological velocity and density profiles. Therefore, geophysical requirement of an oxygen-rich outer core supported the hypothesis of accretion and core formation in an oxidised environment.

DECORE scientists also noted that this oxidised environment is akin to the oxidation state of asteroids like 4 Vesta, which is typical of the type of object from which the Earth is believed to have accreted.

Related information

Keywords

Earth, core, DECORE, accretion, silicate, mantle, magma ocean, siderophile, large-volume presses, anvil cell, 4 Vesta
Record Number: 188429 / Last updated on: 2016-08-31
Domain: Environment