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A team of Earth scientists at Stanford University have shown that iron can flow out of rock at high pressures, yielding new theories on how the core of our planet formed.
The team, led by Wendy Mao, squeezed rocks containing iron to huge pressures between the tips of a pair of diamonds, and imaged the result with X-rays. They saw molten metal flowing through the rocks.
The exact process under which the Earth's core formed has been under debate for some time. The most commonly accepted theory is that the iron that comprises the planet's core separated early in the planet's life when the area outside the core was still liquid, sinking with gravity to the centre in a way similar to how wax moves within a lava lamp.
However, Mao's results suggest a different process - that the iron was able to travel through the solid mantle later in the Earth's lifespan, percolating through to the centre. Their results were published in Nature Geoscience. "In order for percolation to be efficient, the molten iron needs to be able to form continuous channels through the solid," Mao told the BBC. "Scientists had said this theory wasn't possible, but now we're saying -- under certain conditions that we know exist in the planet -- it could happen. So, this brings back another possibility for how the core might have formed."
That possibility means that the formation of the core may not have happened all at once, as previously assumed, but in a series of stages that then had an influence on the chemistry of our planet's interior.
More work will be necessary to know for sure, but Mao says this knowledge is within our grasp: "We know that Earth today has a core and a mantle that are differentiated. With improving technology, we can look at different mechanisms of how this came to be in a new light."
This article was originally published by WIRED UK
