Study: Eruption of Diamond-Rich Kimberlite Pipes Linked to Continental Fractures

An international team led by geologists at the University of Southampton in England believes that the eruption of kimberlite pipes — the molten rock that blasts diamonds from deep within the Earth to the surface — is statistically linked with the fracturing of the Pangea supercontinent.

Geologists believe that some 300 million years ago a massive supercontinent incorporated nearly all the landmasses on Earth. Then, about 200 million years ago, Pangea began to shift and break apart, forming the early configurations of the continents we recognize today.

Utilizing statistical analysis, along with AI (artificial intelligence) machine learning software, the scientists were able to map the location and timing of kimberlite eruptions along the geological fault lines of the broken continents. Interestingly, when the continents snapped apart from each other, the kimberlites did not form right away, say the scientists. Instead, they occurred 20 to 30 million years later.

The computer models revealed that when continental plates tore apart, a number of events eventually led to the eruption of kimberlite magma. As the rock stretched and became thinner, a rift formed and the hot mantle moved in to fill the gap.

The scientists also believe that the kimberlite eruptions initially occurred at the edges of tectonic plates and continued to migrate inland in an undulating pattern at a rate of about 20 kilometers every million years.

Over many millions of years, the kimberlite pipes emerged vast distances from the original continental break. This solved the disturbing riddle of how kimberlite pipes have been discovered so far from the coasts of existing continents.

“It was an elephant in the room that no one had a good explanation for,” Thomas Gernon, a geologist at the University of Southampton, told science.org. “Kimberlites seem to be responding to rhythms of supercontinents.”

Gernon told science.org that the greatest interest in the study, which was recently published in Nature magazine, may come from commercial diamond miners. Theoretically, the research could provide strategies for locating undiscovered kimberlites.

“You should be able to pinpoint, roughly, the sweet spot for diamonds,” he said.

The accompanying video represents a sonification of kimberlite eruptions over time. Each eruption is represented by a note, with higher latitude eruptions producing higher-pitched tones.

Credit: Painting of Mir Diamond mine by Shanabethmason, CC BY-SA 4.0, via Wikimedia Commons.