While the depth of the oceans hides several secrets, there is one that was recently discovered thanks to research conducted by a team of scientists at Macquarie University in Sydney, Australia.
The group of researchers carried out experiments that recreate extreme conditions of the terrestrial interior, and detected that the sea water in the sediments of the bottom of the ocean reacts in the correct way to produce the balance of salts that is found in diamonds.
The studies, published in Science Advances, point out that small traces of salt trapped within diamonds show that precious stones are formed from ancient sea beds that were buried 124 miles away.
“We knew there should have been some kind of salty liquid while the diamonds were being formed, and now we have confirmed that the marine sediment fits perfectly,” study lead author Michael Forster said in a statement.
For this process to occur, a large seafloor slab would have to slip to a depth of more than 124 miles below the surface rather quickly, in a process known as subduction in which one tectonic plate slides under another.
Thomas Stachel, an expert on diamonds at the University of Alberta, points out that this mechanism may not apply to the oldest diamonds that formed billions of years ago on early Earth, when our recent planet was much hotter. But for the most recent diamonds, “it’s definitely a very good and interesting explanation”.
Normally, diamonds are formed almost 100 miles below the earth’s surface and crystallize in the so-called cratonic roots, regions of ancient and rigid mantle that underpin the overlying continents.
According to National Geographic, the maximum depth drilled to date is no more than 7.5 miles, so no one has been able to study directly what happens at these extreme depths.
We can only enjoy diamonds because they come to the surface during rare volcanic eruptions that unearth molten rock from the depths known as kimberlite magma. But the exact conditions that cause its formation have been a mystery for years.