Oceans of water trapped deep beneath the surface of the United States could be the largest deposits of the substance anywhere on the planet. This water is found in a bizarre state, unlike any encountered in day-to-day life.
Northwestern University researchers, along with colleagues from the University of New Mexico, found evidence of vast storehouses of the material deep in Earth's mantle.
Water deep underground would not be in the form of liquid, ice or steam. Subjected to temperatures of 2,000 degrees Fahrenheit and enormous pressures, the familiar molecule of H2O divides into hydroxyls, the main component of alcohols, and oxygen. The two chemical components can combine into water.
Steve Jacobsen, a geophysicist at Northwestern University and seismologist Brandon Schmandt of the University of New Mexico, discovered pockets of magma 410 miles beneath the Earth. They believe this provides evidence of the ingredients of water in the mantle of our planet.
Jacobsen provided evidence for this theory with his experiments, subjecting a mineral called ringwoodite to conditions similar to those found 410 miles underground.
Geologists have long wondered how much water is transferred between the oceans of the Earth and reservoirs beneath the crust. This material can be carried hundreds of miles through the ground by tectonic forces, driven by continental drift.
"I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades," Jacobsen said.
Water driven into the mantle can help drive melting of rock, forming polls of magma.
Scientists have long believed water could be trapped in the mantle of the Earth, between 250 and 410 miles under the ground. This study was the first to provide evidence of water in a "transition zone" that extends under most of the continental United States.
"Melting of rock at this depth is remarkable because most melting in the mantle occurs much shallower, in the upper 50 miles," Schmandt said.
Researchers estimated that if just one percent of the mass of the transition zone of mantle is composed of water, it could contain three times as much material as all the world's oceans combined.
In March 2014, a study published in the journal Science examined a piece of ringwoodite that was brought to the surface from 400 miles underground by a volcano. Analysis revealed a surprising concentration of water bound in the rock.
Study of magma pools within the Earth's mantle could aid geologists investigating the formation of the Earth.
Discovery of magma pools beneath the United States and their possible connection to water reservoirs was detailed in the journal Science.
