Supercomputers have revealed the giant 'pillars of heat' funneling diamonds upward from deep within Earth

Most diamonds are formed deep inside Earth and brought close to the surface in small yet powerful volcanic eruptions of a kind of rock called "kimberlite.

Our supercomputer modeling, published in Nature Geoscience, shows these eruptions are fueled by giant "pillars of heat" rooted 2,900 kilometers below ground, just above our planet's core.

Understanding Earth's internal history can be used to target mineral reserves—not only diamonds, but also crucial minerals such as nickel and rare earth elements.

Kimberlite and hot blobs

Kimberlite eruptions leave behind a characteristic deep, carrot-shaped "pipe" of kimberlite rock, which often contains diamonds. Hundreds of these eruptions that occurred over the past 200 million years have been discovered around the world. Most of them were found in Canada (178 eruptions), South Africa (158), Angola (71) and Brazil (70).

Between Earth's solid crust and molten core is the mantle, a thick layer of slightly goopy hot rock. For decades, geophysicists have used computers to study how the mantle slowly flows over long periods of time.

In the 1980s, one study showed that kimberlite eruptions might be linked to small thermal plumes in the mantle—feather-like upward jets of hot mantle rising due to their higher buoyancy—beneath slowly moving continents.

It had already been argued, in the 1970s, that these plumes might originate from the boundary between the mantle and the core, at a depth of 2,900km.

Then, in 2010, geologists proposed that kimberlite eruptions could be explained by thermal plumes arising from the edges of two deep, hot blobs anchored under Africa and the Pacific Ocean.

And last year, we reported that these anchored blobs are more mobile than we thought.

However, we still didn't know exactly how activity deep in the mantle was driving kimberlite eruptions.

https://phys.org/news/2023-05-supercomputers-revealed-giant-pillars-funneling.html