Scientists Reveal How Explosive Kimberlite Eruptions Bring Diamonds

Diamonds may be symbols of beauty and strength, but their journey to the surface is nothing short of violent. More than 70% of the world's diamonds are mined from kimberlites - rare volcanic pipes that erupt from over 150 kilometers deep in Earth's mantle. Despite decades of research, the exact trigger behind these explosive eruptions has remained mysterious.

Now, a new study published in Geology reveals the missing piece: volatile compounds such as carbon dioxide (CO2) and water (H2O). Using advanced simulations, researchers at the University of Oslo have shown that these ingredients are essential for making kimberlite magmas buoyant enough to rocket diamonds to the surface - fast enough to preserve them before they transform back into ordinary graphite.

Diamonds on a Fiery Ride

Kimberlites are often described as carrot-shaped pipes piercing Earth's crust. Their magmas ascend at astonishing speeds - sometimes estimated at nearly 80 miles per hour. Along the way, they scoop up fragments of mantle rock, delivering both diamonds and valuable geological clues about Earth's deep interior.

“They're fascinating and still very enigmatic rocks,” said Ana Anzulović, doctoral fellow at the Centre for Planetary Habitability, University of Oslo, and lead author of the new study.

Modeling the Unseen Magma

Because kimberlite magmas change drastically on their way up, scientists can't directly observe their original“parental” composition. To work around this, Anzulović's team turned to chemical modeling and molecular dynamics simulations.

Focusing on Canada's Jericho kimberlite, which erupted through the Slave craton, they tested how varying levels of CO2 and H2O influenced the melt's density and buoyancy. The simulations revealed that at least 8.2% CO2 is required for the magma to remain buoyant enough to erupt. Without it, the melt would stall deep underground - and diamonds would never make it to the surface.

The Roles of Water and Carbon

The team also discovered that water and carbon dioxide play complementary roles in kimberlite eruptions:

Water keeps the melt fluid and mobile by enhancing atomic diffusion.

Carbon dioxide structures the melt at high pressures, but near the surface, it degasses explosively, driving the eruption upward.

“Our most volatile-rich composition can carry up to 44% of mantle rock to the surface,” Anzulović explained.“That's an impressive amount for such a low-viscosity melt.”

A Step Toward Solving the Mystery

By quantifying, for the first time, how much CO2 and H2O are required to trigger kimberlite eruptions, this study provides fresh insight into one of Earth's most violent and valuable geological processes.

“It's remarkable that by modeling chemistry on an atomic scale, we can understand a process powerful enough to bring diamonds to the surface,” said Anzulović.

MENAFN25092025007385015968ID1110109311