Scientists have discovered a reservoir of water three times the size of all the oceans beneath the Earth’s surface, according to an international study. The water has been found between the transition zone of the Earth’s upper and lower mantles. The research team analyzed a speed diamond formed 660 meters below Earth’s surface using techniques such as Raman spectroscopy and FTIR spectrometry, ANI reported.
The study confirmed something that had long been just a theory, which is that ocean water accompanies entrained plates and thus enters the transition zone. This means that our planet’s water cycle includes the Earth’s interior.
“These mineral transformations greatly impede the movement of rock in the mantle,” explains Prof. Frank Brenker from the Institute of Geosciences at Goethe University in Frankfurt. For example, mantle plumes — rising columns of hot rock from the deep mantle — sometimes stop directly below the transition zone. The movement of mass in the opposite direction also comes to a standstill.
Brenker says, “Subduction plates often struggle to break through the entire transition zone. So there’s a whole graveyard of such plates in this zone under Europe.”
Until now, however, the long-term effects of “draining” material into the transition zone on the geochemical composition and whether greater amounts of water were present were unknown. Brenker explains: “The subducting plates also carry deep-sea sediments into the Earth’s interior. These sediments can contain large amounts of water and CO2. But until now it was unclear how much enters the transition zone in the form of more stable, hydrous minerals and carbonates. — and it was therefore unclear whether really large amounts of water are stored there.”
The prevailing conditions would certainly be conducive to that. The dense minerals wadsleyite and ringwoodite (unlike the olivine at shallower depths) can store large amounts of water, so much so that the transition zone could theoretically absorb six times the amount of water in our oceans. “So we knew that the boundary layer has a tremendous capacity to store water,” Brenker says. “However, we didn’t know if it actually did that.”
An international study involving the geoscientist from Frankfurt now provides the answer. The research team analyzed a diamond from Botswana, Africa. It was formed at a depth of 660 kilometers, right at the interface between the transition zone and the lower mantle, where ringwoodite is the predominant mineral. Diamonds from this region are very rare, even among the rare diamonds of super-deep origin, which make up only one percent of the diamonds. The analyzes revealed that the stone contains numerous ringwoodite inclusions – which show a high water content. The research group was also able to determine the chemical composition of the stone. It was almost exactly the same as that of virtually every fragment of mantle rock found in basalt around the world. This showed that the diamond certainly came from a normal part of the Earth’s mantle. “In this study, we showed that the transition zone is not a dry sponge, but contains significant amounts of water,” says Brenker, adding, “This also brings us one step closer to Jules Verne’s idea of an ocean in the Earth.” is that there is no ocean down there, but water-bearing rock that Brenker said would neither feel wet nor drip water.