You might already know that the oceans absorb carbon dioxide from the atmosphere. But you might be surprised to discover that some of that carbon makes it to the sea floor and gets pushed into the Earth by the movement of the Earth's tectonic plates, where it comes in contact with the mantle and forms a rare type of diamond.
In a newly published article in the scientific journal Nature, researchers from Great Britain's Bristol University shed new light on the process by which the Earth's recycling of carbon through plate subduction, in which the edge of one plate slides under the edge of another plate, and how that process forms so-called superdeep diamonds.
The researchers, who experimented with small samples of synthetic ocean floor rock at high pressures and temperatures, found that those slabs released most of their carbon at conditions equivalent to depths of 186 to 435 miles below the Earth's surface.
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In addition, the researchers tested the reaction of the melted slabs with the mantle. They were able to reproduce the mineral makeup observed in superdeep diamonds, which generally form at depths of below 155 miles.