HQ Team
August 22, 2023: A breakup of tectonic plates results in the generation of diamond-rich magmas from deep inside the Earth, and may help the future of diamond exploration, researchers find.
Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth’s surface.
Global researchers led by the University of Southampton stated that their discovery could pinpoint where diamonds were most likely to be found.
Diamonds, which form under great pressure at depth, are hundreds of millions, or even billions, of years old.
Kimberlites
They are typically found in a type of volcanic rock known as kimberlite. Kimberlites are found in the oldest, thickest, strongest parts of continents – most notably in South Africa, home to the diamond rush of the late 19th century.
The reason behind how and why they got to Earth’s surface has, until now, remained a mystery, the researchers wrote in the journal Nature.
The new research examined the effects of global tectonic forces on these volcanic eruptions spanning the last billion years.
To address this question, the team used statistical analysis, including machine learning, to forensically examine the link between continental breakup and kimberlite volcanism.
20-30 million years ago
The results of the study showed the eruptions of most kimberlite volcanoes occurred 20 to 30 million years after the tectonic breakup of Earth’s continents.
“The pattern of diamond eruptions is cyclical, mimicking the rhythm of the supercontinents, which assemble and break up in a repeated pattern over time,” said Dr Tom Gernon, Associate Professor of Earth Science and Principal Research Fellow at the University of Southampton.
“But previously we didn’t know what process causes diamonds to suddenly erupt, having spent millions – or billions – of years stashed away 150 kilometers beneath the Earth’s surface,” Dr Gernon, the lead author, said.
‘Domino effect’
This discovery prompted the scientists to explore what geological process could drive this pattern.
They found that the Earth’s mantle – the convecting layer between the crust and core – is disrupted by rifting (or stretching) of the crust, even thousands of kilometers away.
“We found that a domino effect can explain how continental breakup leads to the formation of kimberlite magma,” said Dr Stephen Jones, Associate Professor in Earth Systems at the University of Birmingham, and study co-author.
“During rifting, a small patch of the continental root is disrupted and sinks into the mantle below, triggering a chain of similar flow patterns beneath the nearby continent.”
Identify locations
The study could be used to identify the possible locations and timings of past volcanic eruptions tied to this process, offering insights that could enable the discovery of diamond deposits in the future.
Southampton researchers collaborated with the University of Birmingham, the University of Potsdam, and the GFZ German Research Centre for Geosciences.
Researchers were also aided by the Portland State University, Macquarie University, the University of Leeds, the University of Florence, and Queen’s University, Ontario.
