Scientists have identified a mechanism by which important metals, crucial for the manufacture of renewable energy technologies, are transmitted from the Earth’s mantle to the crust.
The team, including researchers from Cardiff University, discovered a “Goldilocks zone” at the base of the earth’s crust where the temperature is just around 1000C for metals to be transported to shallower levels near from the surface, where they can be mined.
The metals in question – including copper, cobalt, tellurium and platinum – are highly sought after due to their use in electrical wiring and technologies such as battery storage devices, solar panels and fuel cells. .
Publication of their findings today in the journal Nature Communicationthe team hopes the results can lead to more targeted, less expensive and more environmentally friendly practices for exploring and extracting key metals.
Metals are mainly stored in the Earth’s mantle – a thick layer of rock located between the core and the Earth’s crust – at depths of more than 25 km, which makes them inaccessible for exploitation.
Yet in some parts of the world, nature can bring these metals to the surface through the flow of liquid rock, called magma, which originates in the Earth’s mantle and rises through the Earth’s crust.
However, until now, the path of the metals to their final disposal site has been uncertain.
In the new study, the team identified a temperature-dependent zone at the base of the Earth’s crust that acts as a valve and intermittently allows metals to rise up to reach the upper crust.
Study co-author Dr Iain McDonald said: “When magmas reach the base of the crust, critical metals are often trapped here and cannot reach the surface if the temperature is too hot or too hot. cold.
“As with Goldilocks, we have found that if the temperature is ‘right’ at around 1000°C, then metals like copper, gold and tellurium can escape from the trap and rise to the surface to form deposits. of ore.”
The study is part of the NERC-funded FAMOS (From Arc Magmas to Ore Systems) project and involved collaborators from Cardiff University, University of Leicester, University of Western Australia and the international mining company BHP.
Professor Jamie Wilkinson, from the Natural History Museum in London, is the principal investigator of the FAMOS project, and added: “This paper represents fantastic work by the project team which sheds new light on the magmatic processes operating deep within Earth’s crust. but which exercise first-rate control over the accessibility of critical metals to humanity. The results will enable more targeted mineral exploration, thereby reducing the environmental footprint associated with the discovery and extraction of green metals.