Scientists at Stanford University have demonstrated how the formation of Earth's core is even more complicated than previously understood. Using new 3D imaging techniques, the scientists used a pair of diamonds to squeeze molten metal through rocks under pressure, showing that iron can be squeezed out of rocky silicates deep beneath the surface of the planet.
The results of the experiment appeared in Nature Geosciences in a paper authored by Stanford's Crystal Shi and Wendy Mao. One of the implications detailed in the paper is that geologists may have to reevaluate the role meteorites played in the formation of the planet.
"We might not be able to use geochemical data from meteorites to constrain the bulk composition of the Earth," commented the University of Edinburgh's Geoffrey Bromiley, who was not involved with the experiment or the paper. "This is currently an important assumption pervading Earth Science."
The planet's core is 5,000 km below the surface, making direct observation impossible through current technology. In order to reproduce the conditions of iron formation inside the planet billions of years ago, the Stanford researchers used synchrotron electron accelerators to generate intense beams of X-rays. This allowed them to observe how iron "percolates" to form rivulets between rocky particles.
The process only works in large bodies such as Earth, which throws into question how smaller bodies might still be able to form cores that appear similar to this planet's core despite much less internal pressure.