Geologists find magma ‘conveyor belt’ that powers the longest supervolcanic eruption on …

An underground “conveyor belt” of magma that has risen to the surface for millions of years has been responsible for the longest stretch of erupting supervolcanoes ever seen on the planet, according to new research.

Changes in the sea floor led to the formation of channels that allowed magma to flow freely, the researchers say. This resulted in an eruption period that extended from approximately 122 million years to 90 million years ago; extraordinary when you consider that these types of currents usually only lasted from 1 to 5 million years.

All of this took place on the Kerguelen Plateau, which now lies beneath the Indian Ocean. It is a large igneous province, or LIP, a widespread accumulation of magma and lava. Scientists can use these LIPs to track volcanic activity back in time.

“Extremely large accumulations of volcanic rocks – known as large volcanic provinces – are of great interest to scientists due to their connection with mass extinctions, rapid climatic disruptions and mineral deposit formation,” 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 the rising magma.

According to the researchers, in the roughly 30 years of intense activity, the Kerguelen plateau has grown by about 20 centimeters per year. In the gigantic size of the LIP – about three times the size of Japan – the lava spill corresponds to 184,000 Olympic swimming pools per year.

The Kerguelen Plateau, due to its unique configuration, has experienced such a long and steady course of supervolcanic activity as the study suggests: a mantle cloud that combines with slowly expanding ridges in the middle of the ocean directing the magma upward.

“The volcanism lasted so long because the magmas caused by the mantle cloud continually flowed through the ocean ridges, which in turn acted as a channel or ‘magma conveyor’ for over 30 million years,” says Hugo Olierook , geologist of Curtin University.

“Other volcanoes would no longer erupt because the channels were clogged with ‘frozen’ magmas as temperatures cooled. For the Kerguelen plateau, the mantle cloud acts as a Bunsen burner, which continued to melt the mantle, resulting in an extraordinarily long period of eruptive activity. ”

These are many volcanic eruptions over the course of many millions of years, but the rate dropped significantly around 90 million years ago and scientists are still not sure why. The associated volcanic activity continues to a much lesser extent today.

It’s a fascinating look into our planet’s past and, of course, also a reference 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 are taking place. take place below the earth’s surface.

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

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

The research was published in geology.