Iceland volcano sits on hottest bit of North Atlantic mantle plume: A magma hotspot


Mighty eruptions at a volcano in Iceland involve huge amounts of lava, so it's no surprise the Bardarbunga volcano lies directly over the hottest portion of the North Atlantic mantle plume, researchers say.

The volcano in central Iceland, which has been ejecting huge amounts of lava since Aug. 31, is evidence that such eruptions require extremely high mantle temperatures deep beneath the Earth's surface to generate such massive amounts of magma, scientists from the University of California Davis and Denmark's Aarhus University say.

"From time to time the Earth's mantle belches out huge quantities of magma on a scale unlike anything witnessed in historic times," says UC Davis earth and planetary science Professor Charles Lesher.

"These events provide unique windows into the internal working of our planet," says Lesher who, along with his former doctoral student Eric Brown, published the findings of their study in the journal Nature Geoscience.

Bardarbunga lies beneath Iceland's Vatnajokull glacier at the junction between the eastern and northern volcanic rift zones where the present-day center of the mantle hot spot beneath Iceland is thought to be.

Such hot spots are thought to be the source of areas known as large igneous provinces that have existed through Earth's history, Lesher says.

Lesher and Brown say their study strongly suggests extreme mantle temperatures are a factor in generating the huge magma volumes that created North Atlantic provinces bordering Greenland and northern Europe.

Some researchers have discounted the role mantle plumes play in their formation, suggesting instead they are the result of chemical anomalies in the mantle.

However, the new findings, based on both the volcanic record of the region over the past 56 million years and computer modeling, put mantle plumes of hot, deep sources of magma back in the forefront.

"There's little doubt that the mantle is composed of different types of chemical compounds, but this is not the dominant factor," Brown says. "Rather, locally high mantle temperatures are the key ingredient."

Bardarbunga has experienced around 300 to 400 eruptions during the past 10,000 years, including one around 8,600 years ago that produced the Earth's largest known lava flow of the last 10,000 years. It was estimated to have been around 21 cubic kilometers in volume and travelling more than 60 miles from the volcano to Iceland's south coast.

In historic times, there have been 23 eruptions at rates of around twice every century, with the last one before the current event taking place in 1910.

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