Jakarta –
The breakup of Earth’s first supercontinent left this planet with unique diamonds. The Argyle Formation in western Australia is the source of 90% of Earth’s pink diamonds.
This is indeed an odd place for diamonds, being on the edge of a continent, rather than in the center, where most diamond mines tend to be, and in a slightly different type of rock from the rock that usually contains diamonds.
Now, new research shows that the strange colors and geology likely stem from the same origin, namely the planet’s plate tectonics some 1.3 billion years ago. Recent studies from other researchers suggest that these large-scale continental movements were also important in bringing diamonds of other colors to the surface.
“The breakup of these continents was fundamental in bringing diamonds out of great depths,” said Hugo Olierook, a researcher at Curtin University, Australia and lead author of a study on the origins of pink diamonds, quoted from Live Science.
The study, published September 19 in the journal Nature Communications, states that pink diamonds are different from blue or yellow diamonds, whose color comes from impurities such as nitrogen and boron.
In contrast, pink diamonds are colored only because their crystal structure has been bent. Argyle also hosts many brown diamonds, which get their color due to greater deformation of the crystal structure.
“Pink, say, is a small push. If you push too hard, it will turn brown,” says Olierook.
The Argyle diamond mine closed in 2020. Research from the 1980s, shortly after the discovery of the cache, estimated the age of the rocks there at about 1.2 billion years.
But even the scientists who conducted the initial research weren’t sure of that number because of technical limitations. Olierook and his colleagues decided to reexamine them using modern equipment, specifically laser ablation technology that allowed them to carefully pinpoint individual crystals in the rock.
The results of this new study reveal that Argyle containing pink diamonds are 100 million years older than previously believed, namely 1.3 billion years. This places its origins right at the start of the breakup of the Nuna supercontinent.
This provides a new picture of how Argyle pink diamonds are formed. First, about 1.8 billion years ago, two pieces of continental crust collided with each other as part of the formation of Nuna.
What eventually became Argyle’s formation was right at this time. The collision of the Earth’s crust may be what caused the diamond to bend and give it its pink color.
The breakup of Nuna, 500 million years later, then brought diamonds to the surface. The continent did not break apart at Argyle, but the stretching that occurred likely weakened the ‘old wounds’ of the continental collision where the formation was located. This weakening allows rock eruptions carrying rare pink diamonds, which occur over days to weeks.
“I think we see how in general, the mantle becomes unstable when supercontinents break apart,” Olierook said.
“The rifting process doesn’t seem to just be happening at the edges of continents, it’s also happening in the middle of continents, and that’s probably what allows diamonds to appear in the middle of continents in many cases,” he said.
Tracing the diamond’s path from depth to the surface is helpful for understanding how carbon enters and exits the planet’s interior. For your information, diamonds are mostly pure carbon.
According to him, Argyle is a quite unique place. But it is possible that pink diamonds can be found elsewhere on Earth. The problem is that if a pink diamond formed at the edge of a continent, then it would have formed there, most likely buried under a lot of eroded rock and sediment.
“I think we will find another Argyle, another pink diamond treasure. But it will take a lot of luck to find it,” he concluded.
Watch the Video “Le Minerale & IDI Collaboration Reminds the Importance of Essential Minerals”
(rns/rns)
2023-09-23 15:00:40
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