Diamond Eruptions from Earth’s Depths Finally Explained

Volcanic eruptions shoot diamonds high into the sky, scattering these precious stones across the Earth’s surface. However, scientists have finally unraveled the secret behind these eruptions.

They’ve discovered what happens over 100 miles underground that propels the crystals upwards with such breathtaking force.

The research offers valuable insights into the mysterious processes behind these rare eruptions and helps identify the areas where diamond-rich deposits are most likely.

Prof Tom Gernon, a geologist at the University of Southampton who led the study said, “There’s a sweetspot in the interior of continents where diamonds form.” He further said, “The question is why on earth do they shoot up from the deep after spending potentially billions of years sat there?”

Findings about the continental plates

An international team of researchers delved into historical data on continental plates – large, sluggish slabs forming Earth’s crust – and kimberlites, the rocks containing diamonds spewed out during eruptions.

Their analysis revealed a significant pattern: over the last billion years, most kimberlite eruptions occurred approximately 25 million years after continental plates split apart.

Upon closer examination, the scientists observed an interesting trend. The initial kimberlite eruptions following the plate breakup were closer to the edges of the plates. However, as time passed, these eruptions shifted toward the middle of the plate.

This discovery sheds new light on the mysterious processes governing diamond-rich eruptions and provides valuable clues to locating such valuable deposits in the future.

Over incredibly long periods, continental plates on Earth undergo a continuous cycle of tearing apart and coming together.

Around 300 million years ago, North and South America, Africa, and Europe were all part of a gigantic supercontinent known as Pangea. However, approximately 175 million years ago, this vast landmass gradually broke apart.

Process of diamond formations

By utilizing computer models of rock and magma, the scientists connected the dots and understood the sequence of events that led to eruptions rich in diamonds. The process commences when continental plates undergo stretching as they start to tear apart.

This stretching action causes the rock to become thinner and disturbs the usual flow of material in the Earth’s mantle, the layer situated directly below the crust.

The disturbance in the mantle becomes potent enough to break off chunks of rock from the base of the continental plate. These rocks are subjected to immense pressure, and over hundreds of millions of years, the carbon deposits within them undergo a structural transformation, eventually giving rise to diamonds.

Kimberlite is a type of lava that comes from depths as great as 300-350 km. On its way to the surface, kimberlite frequently picks up rock & mineral fragments, including diamonds. In fact, kimberlite is the main source of diamonds—the deepest-known objects from Earth’s interior. pic.twitter.com/P6MHgOCsXz

— American Museum of Natural History (@AMNH) April 25, 2018

According to the scientists report in Nature, as the chunks of rock sink into the Earth’s mantle, they trigger disruptive flows that spread outward.

These flows strip away rock layers from the bottom of the plate above, and this domino effect sets the stage for creating diamond-bearing kimberlite magma. Once enough magma forms, it rises rapidly and forcefully erupts through the Earth’s crust.

The most recent kimberlite eruption is estimated 11,000 years ago at Igwisi Hills in Tanzania. However, most of these eruptions occurred during the Cretaceous period, between 146 to 66 million years ago.

Unlike typical volcanic eruptions, kimberlite eruptions leave behind vertical pipe-like holes in the ground, which are the foundation for many diamond mines.