A journey far below Earth’s crust. A global team of intrepid scientists. And a bounty of a quadrillion ton of diamonds, which are darn near impossible to reach. No, it’s not Dwayne Johnson’s next summer blockbuster, but a new discovery from geologists at the Massachusetts Institute of Technology and other universities. Their findings? That, based on sound waves, there is likely an unimaginably large haul of diamonds buried more than 100 miles below our planet’s surface — far deeper than any drilling expedition has been before.
The discovery is the result of an anomaly in seismic activity data kept by agencies like the United States Geological Survey. Scientists are able to use this data to gain an understanding of what the Earth’s interior might look like, since sound waves move at different speeds depending on the temperature, density, and composition of the rocks they travel through. By analyzing this data, the researchers suggest that a fraction of the cratonic roots — the oldest and least movable sections of rock beneath the center of most continental tectonic plates — is probably made up of diamonds.
“This problem was an integrated puzzle that required input from lots of different scientists to work out,” Joshua Garber, from the Earth Science department at the University of California, Santa Barbara, told Digital Trends. “We know that seismic waves generated by earthquakes pass through certain parts of the mantle faster than we expect. We tested numerous combinations of different possible constituents that could explain these wave speeds. We found that one to two percent diamond is compatible with a whole host of constraints including the wave speeds, but also a number of independent datasets. And we know that the amount of diamond required is compatible with the amount of carbon in the bulk Earth and the mantle.”
Garber said that the work is interesting because it gives us a better handle on understanding the distribution of carbon in the deep Earth. Sadly, there is very little chance of anyone managing to retrieve the diamond haul — through human efforts, at any rate.
“The only way these diamonds will get to the surface is through natural excavation by kimberlite pipes,” Garber continued. “Kimberlites are explosive mantle volcanic products that involve the interaction between carbon-hydrogen-oxygen fluids and the mantle, and result in pieces of the cratonic mantle being picked up and carried to the surface. The depths we considered are far too deep for human drilling. The rocks are just too hot and under too much pressure for us to get down there.”
However, he notes that the diamonds we mine at the surface today are also from kimberlites, suggesting that these stones may also one day be naturally brought to the surface. We suggest quietly investing in buckets and storage units.
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