From Earth's deep mantle, scientists find a new way volcanoes form

[Jim__]

From phys.org:

Far below Bermuda's pink sand beaches and turquoise tides, geoscientists have discovered the first direct evidence that material from deep within Earth's mantle transition zone—a layer rich in water, crystals and melted rock—can percolate to the surface to form volcanoes.

Scientists have long known that volcanoes form when tectonic plates (traveling on top of the Earth's mantle) converge, or as the result of mantle plumes that rise from the core-mantle boundary to make hotspots at Earth's crust. But obtaining evidence that material emanating from the mantle's transition zone—between 250 to 400 miles (440-660 km) beneath our planet's crust—can cause volcanoes to form is new to geologists.

"We found a new way to make volcanoes. This is the first time we found a clear indication from the transition zone deep in the Earth's mantle that volcanoes can form this way," said senior author Esteban Gazel, associate professor in the Department of Earth and Atmospheric Sciences at Cornell University. The research published in Nature.

"We were expecting our data to show the volcano was a mantle plume formation—an upwelling from the deeper mantle—just like it is in Hawaii," Gazel said. But 30 million years ago, a disturbance in the transition zone caused an upwelling of magma material to rise to the surface, forming a now-dormant volcano under the Atlantic Ocean and then forming Bermuda.

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