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Fountains of diamonds that erupt from Earth's center are revealing the lost history of supercontinents

In the twilight of the Cretaceous, 86 million years ago, a volcanic fissure in what is now South Africa rumbled to life. Below the surface, magma from hundreds of miles down shot upward as fast as a car on the autobahn — if that car were barreling through solid rock — chewing up rocks and minerals and carrying them toward the surface in a reverse avalanche.

What this looked like on the surface is lost to history, but it may have been as dramatic as the eruption of Mount Vesuvius. What it left behind was a series of carrot-shaped, igneous-rock-filled tubes under low, weathered white hills.

In 1869, a shepherd's discovery of a huge, sparkly rock on a nearby riverbank would catapult this unassuming landscape into infamy. The rock was an enormous diamond that would eventually be known as the Star of Africa, and the white hills hid what would become the Kimberley Mine, the epicenter of South Africa's diamond rush and quite possibly the largest hole on Earth ever dug out by hand.

Thanks to the Kimberley Mine, often called "The Big Hole," the formations where diamonds are found are now known as kimberlites. The formations are sprinkled across the globe, from  Ukraine to Siberia to Western Australia, but they're relatively small and rare. What makes them special is that their magmas come from very deep down. There are still questions about precisely how deep, but they are known to arise from beneath the bases of continents at the border of the hot, convecting mantle. Some may originate even deeper, at the transition between the upper and lower mantle.

 

As such, these magmas tap into very deep, very ancient rock, and they interact with other processes that occur only in the deep Earth — namely, the formation of diamonds. To crystallize plain-old carbon into hard, sparkly diamond requires great pressure, so these gems form at least 93 miles (150 kilometers) down, in the deepest layers of the lithosphere, the scientific term for the crust and relatively rigid upper mantle. Some, known as sub-lithospheric diamonds, form even deeper, down to around 435 miles (700 km). Kimberlites, on their eruptive journeys to the surface, catch diamonds and drag them into the upper crust, delivering them relatively unscathed and sometimes even containing pockets of fluid from the mantle itself. 

Researchers have long known that as tectonic plates grind under one another, they drag down carbon from the surface to depths where it can crystallize into diamond. Now, they're starting to see that what goes down must (sometimes) come up, and that this reappearance of carbon — now pressed into glittering gems — is also tied to the movements of tectonic plates. In particular, diamonds seem to erupt when supercontinents break apart.

"While these are different processes, together the diamonds and kimberlite can inform us about the life cycle of supercontinent times," said Suzette Timmerman, a geologist at the University of Bern in Switzerland who studies diamonds.

Coming to the surface

No one has ever seen a kimberlite eruption firsthand. There have been very few in the past 50 million years, and the most recent possible eruption, in the Igwisi Hills of Tanzania, occurred over 10,000 years ago. Not only that, but the main material in kimberlite, the mineral olivine, weathers away quickly on the surface, said Hugo Olierook, a research fellow at Curtin University in Australia.

This makes studying kimberlites challenging. Scientists are perplexed, for example, about the chemistry of the original source of the melted rock in the mantle, as well as about how kimberlites manage to punch through the stable cores of what geoscientists call "cratons" — the thick interior parts of continents that usually resist disruption.

A handful of recent studies are sketching out a new explanation for why this happens. The first clue is timing. It's long been noted that pulses of kimberlite activity seem to correspond with the approximate timing of supercontinent break-ups, said Kelly Russell, a volcanologist at the University of British Columbia in Canada. A 2018 study led by Sebastian Tappe, a geoscientist at The Arctic University of Norway, took a global look at this coincidence of timing and found that it up: There was a spike in kimberlite eruptions around the breakup of the supercontinent Nuna some 1.2 billion years ago to 1 billion years ago.

Another pulse occurred between 600 million and 500 million years ago, coinciding with the breakup of the supercontinent Rodinia, according to the 2018 research, followed by a smaller pulse between 400 million and 350 million years ago. But the most prolific period, accounting for 62.5% of all known kimberlites, occurred between 250 million and 50 million years ago. That range happens to coincide with the breakup of the supercontinent Pangaea. To some researchers, this suggests that supercontinent cycles are crucial for kimberlite eruptions.

"The breakup of these continents are fundamental to getting these diamonds up from these deep depths," Olierook told Live Science.

Olierook and his team recently analyzed the ages of unusual pink diamonds from a formation in western Australia and found they likely came to the surface about 1.3 billion years ago, within the window of Nuna breaking up. The new discovery links diamonds to the stretching of continental crust, Olierook said.

"It's those extensional forces that allow those little pockets of deep-seated magma to rise to the top," he said.

The march of the kimberlites 

 

Kimberlites form at the base of continents and as they rise quickly, they catch deeper-formed diamonds and drag them to the surface through kimberlite pipes. (Image credit: Rory McNicol for Live Science)© Provided by Live Science

The tricky question, though, is how this happens. To get a kimberlite, there are two key ingredients: deep, melted rock rich in fluids, and a continental disruption that may bring that melt to the surface. No one knows what causes the formation of the kimberlite melt, but the chemistry of kimberlites is very different from that of the mantle rock it melts from. Kimberlites are also rich in volatiles such as water and carbon dioxide, which is what makes them so buoyant and high-velocity. They shoot through the crust like Champagne rushing through an uncorked bottle, ascending at up to 83 mph (134 km/h). For comparison, the magmas that flow out of the volcanoes in places like Hawaii max out at around 13.5 mph (21.7 km/h). 

An August 2023 study used computer modeling to figure out how kimberlites can burst through the thick hearts of continents. The researchers found that the process of rifting, in which continental crust pulls apart, was key. The stretching creates peaks and valleys at both the surface and base of the continent. At the base, these jagged edges allow warm mantle materials to rise, and then cool and fall, creating eddies. These eddies mix materials from the base of the continents, making the frothy, buoyant kimberlites, which can then shoot up toward the surface, carrying any diamonds they might happen to run into on their way up.

This process began right where the continent was rifting apart, but modeling showed that these jagged regions of eddy formation destabilized neighboring areas on the craton, creating the same dynamics closer and closer to the continental interior. The result was a pattern of kimberlite eruptions starting near the rift zone but gradually marching into areas of stable crust. This slow march explains why kimberlite pulses don't peak until a bit after a big breakup begins, said Thomas Gernon, a geologist at the University of Southampton in the U.K. who led the study.

"You will see these peaks of kimberlites seem to happen after big supercontinents have broken up," he said. "But it's not just a one-hit thing; it's something that may last quite a long time after supercontinent breakups." 

 

Instabilities form at the edges of continents but migrate toward the hearts of the "cratons" over millions of years. (Image credit: Rory McNicol for Live Science, adapted from Gernon et al, 2023.)© Provided by Live Science

Kimberlites may be quite common at the bases of continents, said Tappe, whose 2018 study on kimberlites and supercontinent breakups came to similar conclusions as Gernon's. Tappe and his team found that these melts may have been particularly prominent during the breakup of Pangaea, because the mantle, which has been slowly cooling since Earth solidified, reached just the right temperature around 250 million years ago to have kimberlite-type melts dominate. Prior to that period, the rocks in that region may have been too hot to get that combination of melt and volatile material that makes kimberlites so eruptive. This may be one reason why most kimberlite diamond mines date from the breakup of Pangaea. 

Messages in a diamond

As the dull, white hills that once covered the Kimberley Mine attest, kimberlites themselves can't say much about the mantle where they originated. They weather away within a few years, losing much of what makes them interesting on a chemical level. However, the diamonds carried within kimberlites are a different story. They have their own formation histories that don't coincide with the formation of the kimberlite magma itself. But their chance meetings hundreds of miles below the surface mean that bits of the mantle that would never otherwise see daylight can reach human hands.

These bits are microscopic pockets of fluid from the time the diamonds formed. Many of these "inclusions" date back hundreds of millions of years, while a few specimens count their ages in the billions. Plus, some of these diamonds form very deep in the mantle, so certain stones can carry materials from as far down as the boundary between the mantle and the core. 

"Only in kimberlites we can see samples coming from 400 kilometers [250 miles], even down to 2,000 kilometers [1,200 miles]," said Maya Kopylova, a professor of diamond exploration at the University of British Columbia. "No other magmas on Earth do that."

Related: What's the deepest-forming gemstone on Earth? 

 

The rough Cullinan diamond, the largest known gem-quality rough diamond, was pulled from the Kimberley Mine in 1905. Diamonds like these can come from deep inside Earth and reveal billions of years of the planet's history. (Image credit: Public Domain)© Provided by Live Science

While the eruption of diamonds can trace a story of supercontinent breakup, their formation may also provide a clue to how continents come together. In a study published in October 2023 in the journal Nature, Timmerman studied diamonds from Brazil and Guinea that formed between 186 and 434 miles deep (300 to 700 km). By dating fluid inclusions within the diamonds, Timmerman and her colleagues estimated that the diamonds formed around 650 million years ago, when the supercontinent Gondwana was forming. The diamonds probably stuck to the base of the continent and sat there for millennia until Gondwana broke up during the Cretaceous period and kimberlites brought them to surface, Timmerman told Live Science. 

What was important about these superdeep diamonds, Timmerman said, was that they helped explain how continents grow. Supercontinents are built when oceanic crust pushes under continental crust. This process, called subduction, tugs two continents on opposite sides of an ocean closer together. This same subduction brings carbon to the depths, where it can be compressed into diamond.

Down in the mantle, bits of these subducting plates can become buoyant and rise back up, carrying superdeep diamonds with them, Timmerman explained. This material may stick to the bases of continents for millennia, helping them grow from below. It may also explain how superdeep diamonds land in a place where a kimberlite can catch them.

"Deep diamonds can inform us more about subduction processes, mantle convection, liquid-rock interactions and other processes happening below the crust during supercontinent cycles," Timmerman said. 

There are many other questions to answer, she added. For instance, scientists still don't know how subducted plates change the bases of supercontinents and whether that affects how long a supercontinent lasts before breaking up. Another open question is whether this recycled crustal material influences when and where kimberlite magmas form.

Ancient diamonds may also tell us about other milestones in Earth's chaotic history.

Some diamonds are forged from carbon that was incorporated into Earth upon its formation, Olierook said, while others form from carbon from ancient life, dragged down along with slabs of subducted crust. It's possible to tell which process formed the diamonds by analyzing the molecular structure of the carbon within diamond inclusions. These inclusions can thus hold secrets about hazy numbers in Earth history, such as when widespread subduction began or when life in the oceans became prevalent. 

But to get at those answers, researchers will need to get better at figuring out how old diamonds are. And they'll need more diamonds that are both ancient and from the deepest depths.

"Going back in time from the most recent supercontinent breakup to the ones before that," Olierook said, "I strongly suspect there are still lots to be discovered." 

The Moody Blues founder Mike Pinder has died aged 82

The Moody Blues founder and keyboardist Mike Pinder has died aged 82, his family have confirmed.

The family of The Moody Blues founder Mike Pinder have announced that the keyboardist has died at the age of 82. A cause of death has yet to be confirmed.

The official statement regarding Pinder’s death read:  “Michael Thomas Pinder died on Wednesday, April 24th, 2024 at his home in Northern California, surrounded by his devoted family.” 

“Michael’s family would like to share with his trusted friends and caring fans that he passed peacefully. His final days were filled with music, encircled by the love of his family. Michael lived his life with a childlike wonder, walking a deeply introspective path which fused the mind and the heart.” 

The Moody Blues founder Mike Pinder has died aged 82© British rock group The Moody Blues, 26th July 1978. Clockwise from top left, Graeme Edge, Ray Thomas, John Lodge, Mike Pinder and Justin Hayward. (Photo by Keystone/Hulton Archive/Getty Images)

“He created his music and the message he shared with the world from this spiritually grounded place; as he always said, ‘Keep your head above the clouds, but keep your feet on the ground.’ His authentic essence lifted up everyone who came into contact with him. His lyrics, philosophy, and vision of humanity and our place in the cosmos will touch generations to come.” 

Pinder was the band's original keyboardist and vocalist, and he played a key role in shaping their sound; his use of the Mellotron, an early type of synthesizer, was particularly influential in the band's music and helped define their progressive rock style.

Pinder was involved in many of The Moody Blues' early albums, including "Days of Future Passed" (1967), "In Search of the Lost Chord" (1968), and "On the Threshold of a Dream" (1969). 

His distinctive vocals and keyboard work contributed to the band's success during their peak years, but he would leave the band in 1978 expressing a desire to spend more time with his family and take a break from the demands of the music industry.

Pinder released his debut solo album, “The Promise,” in 1976, even before officially departing from The Moody Blues. The album featured a blend of rock and classical influences and included contributions from other notable musicians such as guitarist Joe Walsh.

In 1994, Pinder released another solo album titled “Among the Stars.” The album included collaborations with former Moody Blues bandmate Ray Thomas and other musicians. 

Ancient humans used cave in Spain as burial spot for 4 millennia, 7,000 bones reveal

Starting about 7,000 years ago, ancient humans in what is now northeastern Spain buried their dead deep in a cave, creating a necropolis of sorts that spans about four millennia and now contains more than 7,000 bones, according to archaeologists. And there are signs it may have been used for tens of thousands of years before that.

The Cova dels Xaragalls (Cave of the Ravines) was "a collective burial place," archaeologist Antonio Rodríguez-Hidalgo, a researcher at the Catalan Institute of Human Paleoecology and Social Evolution (IPHES) and the Merida Institute of Archaeology, told Live Science in an email.

He said people were buried in communal graves within the cave starting about 7,000 years ago, during the late Neolithic or New Stone Age, though most of the Chalcolithic ("Copper-Stone") period and throughout the Bronze Age, which ended in Spain about 3,000 years ago.

An analysis of the grave goods buried with the dead — typically ceramics, flint tools and necklaces — suggests that high-status individuals were buried alone in the cave during the late Chalcolithic and Bronze Age, while communal burials within the cave were still used for people lower in society, the researchers found.

Grave goods were especially abundant during the Bronze Age, when some individuals were buried with rich collections of weapons and other items, Rodríguez-Hidalgo said.

One of the Bronze Age skulls has a hole in the cranium made by a trepanation; this individual seems to have suffered from several illnesses, and this may have been an attempt at a cure, he said.

However, "we also know that [he or she] did not survive the intervention since there is no bone regeneration in the hole," Rodríguez-Hidalgo said.

This is the only trepanated skull found in Cova dels Xaragalls so far, but more than 100 trepanation scars have been found on other prehistoric skulls from Spain, he said.   

 

Archaeologists found this bronze dagger among the grave goods for one of the Bronze Age burials in the cave. (Image credit: Antonio Rodríguez-Hidalgo, Instituto de Arqueología de Mérida (CSIC-Junta de Extremadura))© Provided by Live Science

Neanderthal connection?

The Cova dels Xaragalls is in the mountains about 56 miles (90 kilometers) west of Barcelona. It was excavated several times during the 20th century and in 2008; Rodríguez-Hidalgo and his colleagues from IPHES excavated more of it in December 2023.

In addition to indications that the cave was used for burials from the Neolithic until the Bronze Age — a span of roughly 4,000 years — the latest excavations revealed bones of wild goats and charcoal in part of the cave that have been dated to more than 45,000 years ago. At that time, the region was inhabited by Neanderthals; paleoanthropologists think anatomically modern humans — Homo sapiens — replaced Neanderthals throughout Europe by about 40,000 years ago, although modern genetics shows they sometimes interbred. 

 

 

©Provided by Live Science

"This opens the possibility that Neanderthals could have used the cave as well," Rodríguez-Hidalgo said. "This is something to confirm."

It's not clear whether the cave was used continually for burials, or if it was used by various groups in different periods.

"At the moment, we have a few dates that allow us to understand that the cave was used as a tomb for millennia," Rodríguez-Hidalgo said. "Now we have to resolve whether it was continuous or not — we need to undertake a comprehensive radiocarbon dating to clarify this point."

Burial place

 

 

 

©Provided by Live Science

The latest discoveries can help chart how burial customs have changed over time. And although many details of the burials have varied over the millennia the cave was used for this purpose, each grave seemed to be given its own burial place, Rodríguez Hidalgo said.

"The people who lived in the fertile areas of the valleys had to climb a small mountain with the bodies of the dead to put them there," he said, adding that it seemed that different groups, from the Neolithic until the Bronze Age, respected the earlier burials.

The IPHES archaeological team plans to return to Cova dels Xaragalls this month.

"We are doing ancient DNA analysis, ceramic analysis, paleoanthropological studies, and [analyzing] the composition and origin of the metals we have found as grave goods," Rodríguez-Hidalgo said. Because the cave was used for burials for such a long time, "this is an important place," he said.