Geologists discover that the magma ‘conveyor belt’ has the longest eruption in the supervolcano …

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 extended from approximately 122 million years to 90 million years; Extraordinary considering that these types of currents typically only last 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 because they are linked to mass extinctions, rapid climatic disturbances and the formation of mineral 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 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. At the gigantic size of the LIP – about three times the size of Japan – pouring lava is equivalent to 184,000 Olympic-sized swimming pools a year.

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

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

“Other volcanoes would not 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 further melted 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, 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 we left. place beneath the surface of the earth.

“Finding this long and continuous eruptive activity is important as it helps us understand what factors can influence 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.