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According to new research, an underground “conveyor belt” of magma, which has been pushing to the Earth’s surface for millions of years, has been responsible for the longest stretch of erupting supervolcanoes ever seen on the planet, according to new research.
The changes in the sea floor caused channels to form, through which magma could flow freely, the researchers say. This resulted in a long period of eruptions that lasted from about 122 million years ago to 90 million years ago; exceptional, considering that typically these types of flows lasted just 1-5 million years.
All of this took place on the Kerguelen Plateau, which now lies beneath the Indian Ocean. It is known as 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 very interesting to scientists because of their links to mass extinctions, rapid climatic perturbations and the formation of mineral deposits,” says geologist Qiang Jiang of the University. by Curtin in Australia.
Jiang and his colleagues used samples of black basalt rocks taken from the sea floor, along with an argon isotope dating method to determine the diffusion and rise of the LIP while sitting on what is known as a mantle plume. , created by the increase of magma.
During the roughly 30 years of intense activity, the Kerguelen Plateau has increased by about 20 centimeters per year, the researchers say. Across the gigantic size of the LIP – roughly three times the size of Japan – the vent is equivalent to filling 184,000 Olympic-sized swimming pools with lava annually.
The Kerguelen Plateau has seen such a long and steady run of supervolcano activity due to its unique configuration, the study suggests: a mantle plume that combines with slow-diffusing ocean ridges that channel magma upward.
“The volcanism lasted so long because the magmas caused by the mantle plume continuously flowed through the mid-ocean ridges, which subsequently acted as a channel or ‘magma conveyor’ for over 30 million years,” says the geologist Hugo Olierook, of Curtin University.
“Other volcanoes would stop erupting because, as temperatures cool, the channels are clogged with ‘frozen’ magmas. For the Kerguelen Plateau, the mantle plume acts as a Bunsen burner that has continued to allow the mantle to melt, resulting in in an extraordinarily long period of eruptive activity. “
That’s a lot of volcanic eruption activity over the course of many millions of years, but the rate dropped significantly about 90 million years ago, and scientists are still not sure why. The associated volcanic activity continues today, on a much smaller scale.
It’s a fascinating look at our planet’s past history and, of course, informs our study of volcanic activity even today: the more we know about how these types of systems can form and remain active, the better we can understand the interactions that take place under the Earth’s surface right now.
“Finding this long and continuous eruptive activity is important because it helps us understand what factors can control the start and end of volcanic activity,” says geochronologist Fred Jourdan, of Curtin University.
“This has implications for how we understand magmatism on Earth and on other planets as well.”
The research was published in Geology.
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