A controversial new theory suggests massive eruptions of lava that coincided with many of Earth's largest extinctions are linked to two unusually hot blobs of mantle 1,700 miles beneath the crust that formed just after Earth itself, 4.5 billion years ago, NewScientist.com reported Wednesday.
Huge amounts of magma have periodically burst through the planet's crust to form enormous oceans of lava that poisoned the atmosphere and wiped out entire groups of animals.
Such events flooded almost 40,000 square miles, creating distinct geological regions known as large igneous provinces or LIPs, formed when the dinosaurs went extinct.
"There is an amazing correlation between mass extinctions and LIPs," Andrew Kerr at the University of Cardiff says.
Matthew Jackson at Boston University and colleagues say they've found evidence LIPs are fed by 4.5-billion-year-old stores of mantle. Jackson's team found 62-million-year-old basalts from the North Atlantic LIP contain isotopes of elements in ratios that reflect the chemistry of early Earth's mantle.
Studies to probe the mantle's structure with seismic waves have revealed two unusual areas of magma some 1,700 miles beneath Africa and the Pacific Ocean, and research suggests most LIPs formed while one of these two areas lay directly beneath them.
"It's an interesting idea -- that a giant blob of hot magma might burp from near Earth's core every now and then, causing havoc for life," says Gerta Keller at Princeton University.
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