Through a series of laser-heated diamond anvil cell experiments at high pressure (350,000 to 700,000 atmospheres of pressure) and temperatures (5,120 to 7,460 degrees Fahrenheit), the team demonstrated that the depletion of siderophile (also known as "iron loving") elements can be produced by core formation under more oxidizing conditions than earlier predictions.
An artist's conception of Earth's inner and outer core
"We found that planet accretion (growth) under oxidizing conditions is similar to those of the most common meteorites," said LLNL geophysicist Rick Ryerson.
The research appears in the Jan. 10 edition of Science Express.
While scientists know that the Earth accreted from some mixture of meteoritic material, there is no simple way to quantify precisely the proportions of these various materials. The new research defines how various materials may have been distributed and transported in the early solar system.
As core formation and accretion are closely linked, constraining the process of core formation allows researchers to place limits on the range of materials that formed our planet, and determine whether the composition of those materials changed with time. (Was accretion heterogeneous or homogeneous?)
"A model in which a relatively oxidized Earth is progressively reduced by oxygen transfer to the core-forming metal is capable of reconciling both the need for light elements in the core and the concentration of siderophile elements in the silicate mantle, and suggests that oxygen is an important constituent in the core," Ryerson said.
The experiments demonstrated that a slight reduction of such siderphile elements as vanadium (V) and chromium (Cr) and moderate depletion of nickel (Ni) and cobalt (Co) can be produced during core formation, allowing for oxygen to play a more prominent role.
Planetary core formation is one of the final stages of the dust-to-meteorite-to-planet formation continuum. Meteorites are the raw materials for planetary formation and core formation is a process that leads to chemical differentiation of the planet. But meteorite formation and core formation are very different processes, driven by different heat sources and occurring in very different pressure and temperature ranges.
"Our ability to match the siderophile element signature under more oxidizing conditions allows us to accrete the Earth from more common, oxidized meteoritic materials, such as carbonaceous and ordinary chondrites," Ryerson said.
The earth's magnetic field is generated in the core, and protects the Earth from the solar wind and associated erosion of the atmosphere. While the inner core of the Earth is solid, the outer core is still liquid. The ability to preserve a liquid outer core and the associated magnetic field are dependent on the composition of the core and the concentration of light elements that may reduce the melting temperature.
"By characterizing the chemical interactions that accompany separation of core-forming melts from the silicate magma ocean, we can hope to provide additional constraints on the nature of light elements in the present-day core and its melting/freezing behavior," Ryerson said.
Other teams members include Julien Siebert and Daniele Antonangeli (former LLNL postdocs) from the Université Pierre et Marie Curie, and James Badro (a faculty scholar at LLNL) from the Institut de Physique du Globe de Paris.
More Information"Looking at Earth in action"
Anne Stark | EurekAlert!
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology