The Bermuda Volcano was formed in a way that has never been seen elsewhere on Earth

Scientists have discovered that a volcano under Bermuda had formed in a way never seen before. The volcano appears to have been created by materials emerging from an area deep beneath the Earth's surface, the transition zone.

The transition zone is the region between the upper and lower mantle. It extends 250 to 400 miles below the surface of the planet and is rich in water, crystals and molten rocks.

Volcanoes normally form when the tectonic plates are brought closer together or apart, producing a crack on the surface of the Earth where magma can escape. They can also form at "hot spots", where mantle plumes rise and melt a hole in the plate – Hawaii is an example.

Researchers have now discovered that volcanoes can also form when material rises from the transition zone. The team estimates that a disturbance in the transition zone caused the material of this layer to melt and rise to the surface. Their results are published in the journal Nature.

The researchers analyzed a dormant volcano under the Atlantic Ocean, responsible for the formation of Bermuda. They examined the chemical composition of a 2,600-foot core sample; by understanding its composition, they could get an idea of ​​the volcanic history of Bermuda.

"Before our work, Bermuda was interpreted as the result of a deep thermal anomaly in the Earth's mantle, but no direct data corroborated it.This is due to the fact that the volcanic edifice is entirely covered with limestone "said Cornell Esteban Gazel, one of the authors of the study, said Newsweek.

In a statement, he said that they were expecting to show that the volcano was a coat plume formation like that of Hawaii. This is not what they found, however. The measurements taken from the base sample did not look like anything at all, suggesting that the lava originated from an unidentified source previously.

The samples contained signatures of the transition zone. Compared to samples taken in the subduction zones, there was more water trapped in the crystals. We know that the transition zone contains huge amounts of water. According to one study, there would be three times more water in this region of the Earth than in all the oceans of the world.

"I first suspected that the volcanic past of Bermuda was special because I sampled the core and I noticed the diversity of textures and mineralogy preserved in the various flows lava, "said in the statement Sarah Mazza, senior author of the University of Münster, Germany. "We quickly confirmed the extreme enrichments in trace mineral compositions. It was exciting to review our first results … the mysteries of Bermuda began to unfold. "

Illustration showing how the volcano was formed. Wendy Kenigsberg / Clive Howard – Cornell University, modified from Mazza et al. (2019)

The numerical models developed by the team indicate that a disturbance in the transition zone forced the material to rise. This would have occurred about 30 million years ago and provided the foundation on which Bermuda rests today.

"We have found a new way to make volcanoes," Gazel said in a statement. "This is the first time we find a clear indication of the transition zone located at the bottom of the Earth's mantle that volcanoes can form this way."

The researchers think that there will be other examples of volcanoes formed in this way. "Through this work, we can demonstrate that the Earth's transition zone is an extreme reservoir of chemicals," said Gazel. "We are just beginning to recognize its importance in terms of global geodynamics and even volcanism."

Talk to Newsweek, he added, "I think that many hot spot sites (…) are not deeply anchored at the boundary between the core and the mantle probably have a past similar to that of Bermuda."

This article has been updated to include quotes from Gazel.