A group of geologists has recently achieved a breakthrough in identifying potential sites for the formation of diamonds.
Diamonds, the hardest naturally occurring material we have found, originate under the extreme conditions of immense pressure and high temperatures deep within the Earth's interior.
These precious gems are occasionally pushed to the surface in molten rock formations known as kimberlite. However, there are currently two competing theories regarding what is responsible for this rush of kimberlite which brings diamonds to the surface.
In a recent study, these theories were closely examined by a research team. In a piece for The Conversation study author and Associate Professor in Earth Science at the University of Southampton, Thomas Gernon explained: “one proposes that kimberlite magmas exploit the ‘wounds’ created when the Earth’s crust is stretched or when the slabs of solid rock covering the Earth - known as tectonic plates - split up.”
“The other theory involves mantle plumes, colossal upwellings of molten rock from the core-mantle boundary, located about 2,900km [1,802] beneath the Earth’s surface.”
However, neither of these theories adequately explains how magma manages to find its way through the Earth's crust, or the specific composition of the resulting kimberlite.
By employing statistical analysis and machine learning, the team analysed the breakup of continents and its correlation with kimberlite formation. Their findings indicated that the majority of kimberlite volcanoes erupt 20 to 30 million years after tectonic breakup.
“It also added a major clue,” Gernon explained. “Kimberlite eruptions tend to gradually migrate from the continental edges to the interiors over time at a rate that is uniform across the continents.”
Delving deeper into their investigation through computer-generated models, the team ultimately concluded that diamond eruptions stem from a "domino effect." As continents gradually drift apart from each other, they generate rifts of thinned crust.
As this happens, regions of thick, cold rock descend into the hot magma beneath, inducing an upsurge of the mantle, which in turn triggers a similar flow in nearby continents.
Gernon elaborated on the team's findings, saying, "Various other results from our computer models then advance to show that this process can bring together the necessary ingredients in the right amounts to trigger just enough melting to generate gas-rich kimberlites,” Gernon explained.
“Once formed, and with great buoyancy provided by carbon dioxide and water, the magma can rise rapidly to the surface carrying its precious cargo.”
Moreover, the same methodology could potentially be employed to locate diamonds and other rare elements.
“The processes triggering the eruptions that bring diamonds to the surface appear to be highly systematic,” Gernon siad. “They start on the edges of continents and migrate towards the interior at a relatively uniform rate.”
The study is published in the journal Nature.
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