Geologists find that magma ‘conveyor belt’ has the longest supervolcano eruption...

An underground “conveyor belt” of magma that has been rising to the surface for millions of years was responsible for the longest stretch of erupting supervolcanoes ever seen on the planet, according to new research.
Shifts in the sea floor led to the formation of channels that allowed magma to flow freely, researchers say. This resulted in an extended eruption period from about 122 million years to 90 million years; Extraordinary when you consider that these types of currents typically only lasted 1 to 5 million years.

This all took place on the Kerguelen Plateau, which is now under the Indian Ocean. It is a large igneous province, or LIP, a widespread accumulation of magma and lava. Scientists can use these LIPs to trace volcanic activity back through time.

“Extremely large accumulations of volcanic rocks – known as large volcanic provinces – are of great interest to scientists because they are related to mass extinctions, rapid climatic disturbances and the formation of ore deposits,” says geologist Qiang Jiang of Curtin University in Australia.

Jiang and his colleagues used samples of black basalt rocks taken from the ocean floor, along with an argon isotope dating method, to determine the spread and rise of the LIP, which was on a so-called mantle cloud created by rising magma.

In the roughly 30 years of intense activity, the Kerguelen Plateau rose by around 20 centimeters per year, according to the researchers. At the gigantic size of the LIP – about three times the size of Japan – pouring lava equals 184,000 Olympic swimming pools per year.

The Kerguelen Plateau has had such a long and steady course of supervolcanic activity because of its unique configuration, as the study suggests: a mantle cloud that connects to slowly expanding ridges in the mid-ocean that direct the magma upwards.

“The volcanism lasted so long because magmas caused by the mantle cloud continuously flowed through the central ocean ridges, which in turn acted as a canal, or” magma conveyor, “for more than 30 million years,” said Hugo Olierook, Curtin geologist University.

“Other volcanoes would not erupt because the channels were clogged with ‘frozen’ magmas as the temperatures cooled. For the Kerguelen Plateau, the mantle cloud acts as a bunsen burner, which further melted the mantle, resulting in an extraordinarily long period of eruptive activity. ”

That’s a lot of volcanic eruption over many millions of years, but the rate dropped significantly about 90 million years ago, and scientists still aren’t sure why. The associated volcanic activity continues to this day to a much lesser extent.

It’s a fascinating look at our planet’s past and, of course, a clue to our study of volcanic activity in the present – the more we know how such systems can form and remain active, the better we can understand the interactions that took place before going take place under the surface of the earth.

“Finding this long, continuous eruption activity is important as it helps us understand what factors can influence the onset and end of volcanic activity,” says geochronologist Fred Jourdan of Curtin University.

“This has an impact on how we understand magmatism on earth and on other planets.”

The research was published in geology.