Vast Oceans of Water may be Trapped in Earth's Interior , may be Wellspring for World's Oceans

The mineral is thought to exist in the mantle at depths between about 500 and 700 km; these samples were lab grown.
(Photo : Steve Jacobsen / Northwestern University)

Tech Times
 
Researchers from Northwestern University and the University of New Mexico report evidence for potentially oceans worth of water deep beneath the United States. Though not in the familiar liquid form -- the ingredients for water are bound up in rock deep in the Earth’s mantle -- the discovery may represent the planet’s largest water reservoir.

A reservoir of water lying deep under the Earth's surface may contain triple the volume of every one the world's oceans and may even be the "wellspring" source of them, U.S. researchers say.

Although not in a liquid form most familiar to all of us -- it is instead bound within rocks deep in the Earth's mantle -- it likely represents the largest reservoir of water on Earth, scientists at the University of New Mexico and Northwestern University say.

Writing in the journal Science, they report finding pockets of melted magma 400 miles underneath the North American continent that are likely signatures that water exists at those depths.

Scientists have long questioned whether the mantle, the rocky, hot layer between the Earth's crust and its core, might contain water bound up and trapped within rare minerals.

The new discovery is evidence water can be transported from the surface of the Earth to great depth by plate tectonics, the movement of continents and plates over the Earth's surface.

"Geological processes on the Earth's surface, such as earthquakes or erupting volcanoes, are an expression of what is going on inside the Earth, out of our sight," says geophysicist and study co-author Steve Jacobsen at Northwestern. "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."

Movement and partial melting of rocks in the mantle's transition zone -- a region between the mantle's lower and upper layers from around 250 to 400 miles deep -- could allow water to become tightly bound to the minerals there, the researchers said.