Seismic surveys find evidence of a superplume in Earth's mantle that fueled ancient megaeruptions in the Pacific.
© Pseudopanax, CC BY-SA 4.0
One of the seismic lines that collected evidence of an ancient superplume ran through the Akatarawa Forest of New Zealand’s North Island.
Around 120 million years ago, in what's now the southwest Pacific Ocean, massive volcanic eruptions spewed out enough basalt to form a vast underwater plateau that could have covered
around 1% of Earth's surface. In the aftermath, worldwide temperatures rose dramatically, contributing to the "greenhouse Earth" of the Cretaceous period — a time when dinosaurs thrived and forests carpeted Antarctica.
The source of such extreme volcanism
could have been a giant mantle plume, or superplume, according to new evidence published in
Science Advances in May. First proposed in the 1970s, the plume hypothesis has become the mainstream
explanation for volcanism that occurs far from plate boundaries — though a vocal minority has
pointed out that physical evidence for plumes' existence remains thin.
According to plume theory, a plume is born where Earth's core meets its mantle, forming an expanding blob that gradually travels toward the crust. Heat from the head of the plume is thought to melt the crust above it and cause hot spot volcanoes, like those making up the island chain of Hawaii.
Picture a lava lamp, said
Simon Lamb, a geophysicist at Te Herenga Waka-Victoria University of Wellington (VUW) in New Zealand and coauthor of the new research. "Once in a while, one of these blobs is just unusually large" — a superplume, Lamb said. He and his colleague
Tim Stern, also a geophysicist at VUW, said they've found some rare evidence for one.
Comment: Check out the following short videos below to see the awesome visuals and for more on the experiments findings: