Researchers have discovered a pattern where diamonds spew from deep beneath Earth’s surface in huge, explosive volcanic eruptions. The breakup of supercontinents may trigger explosive eruptions that send fountains of diamonds shooting up to Earth's surface.

The breakup of supercontinents may trigger explosive eruptions that send fountains of diamonds shooting up to Earth's surface.

Diamonds form deep in Earth's crust, approximately 93 miles (150 kilometers) down. They are brought up to the surface very quickly in eruptions called kimberlites. These kimberlites travel at between 11 and 83 mph (18 to 133 km/h), and some eruptions may have created Mount Vesuvius-like explosions of gases and dust, said Thomas Gernon, a professor of Earth and climate science at the University of Southampton in England.

Figure 1. Fountains of Diamonds Erupt as Supercontinents Break Up

Fountains of Diamonds Erupt as Supercontinents Break Up is shown in Figure 1. Researchers noticed that kimberlites occur most often during times when the tectonic plates are rearranging themselves in big ways, Gernon said, such as during the breakup of the supercontinent Pangaea. Oddly, though, kimberlites often erupt in the middle of continents, not at the edges of breakups — and this interior crust is thick, tough and hard to disrupt.

"The diamonds have been sat at the base of the continents for hundreds of millions or even billions of years," Gernon said. "There must be some stimulus that just drives them suddenly, because these eruptions themselves are really powerful, really explosive."

Gernon and his colleagues began by looking for correlations between the ages of kimberlites and the degree of plate fragmentation occurring at those times. They found that over the last 500 million years, there is a pattern where the plates start to pull apart, then 22 million to 30 million years later, kimberlite eruptions peak. (This pattern held over the last 1 billion years as well but with more uncertainty given the difficulties of tracing geologic cycles that far back.)

Diamonds can erupt to the surface

Scientists have known for some time that a special form of magma called kimberlite can rip through the Earth's core at staggering speeds carrying diamonds.

This magma is rich in gases carbon dioxide and water. That propels it from the depths of the Earth, like soda gushing from a bottle that has been shaken too much.

This magma can pick up diamonds along the way as it bubbles to the surface. This creates diamond-rich areas, that are ripe for mining.

However, if you're thinking of planning your next holiday to see a diamond eruption, think again. No human in history has seen one of these happen, and that's because these tend to happen near a time of great continental disruption, like when Pangaea broke apart about 200 million years ago.

The most recent eruption of this kind is believed to have taken place 11,000 years ago, according to The Guardian.

"The pattern of diamond eruptions is cyclical, mimicking the rhythm of the supercontinents, which assemble and break up in a repeated pattern over time," Gernon said.

In fact, scientists found that most kimberlite volcanoes occurred 20 to 30 million years after the tectonic breakup of Earth's continents.

The continental divide stretches the Earth's crust like pizza dough

You would expect the kimberlite to erupt near the borders of the continent, where the plates are being ripped apart by the continental divide.

But instead, it tends to appear in "a sweet spot in the interior of continents where diamonds form," Gernon said.

By analyzing the eruptions more closely, scientists think they've cracked this mystery. And it's down to a "domino effect," that churns the kimberlite closer and closer to the center of continents, Stephen Jones, co-author on the study and Professor of geology at the University of Birmingham, said in the statement.

As continents are pulled apart by the divide, it stretches the Earth's crust like a pizza dough. That thinning causes the crust to sink into the Earth's mantle below.

This interaction rips off big chunks of the rock from the continental plate. As these drop into the mantle, they drive a churning motion beneath the continent, said Jones.

"Remarkably, this process brings together the necessary ingredients in the right amounts to trigger just enough melting to generate kimberlites," said Gernon.[2]

Reference:

1. https://www.scientificamerican.com/article/fountains-of-diamonds-erupt-as-supercontinents-break-up/
2. https://www.businessinsider.in/international/news/fountains-of-diamonds-erupt-from-the-ground-when-continents-break-up-say-scientists-and-it-could-help-uncover-new-deposits/articleshow/102911949.cms

Cite this article:

Gokula Nandhini K (2023), Fountains of Diamonds Erupt as Supercontinents Break Up, AnaTechmaz, pp.563