Nature & Environment
Mystery Source of African Lava Revealed: Massive Outpourings Close to Earth's Surface
Catherine Griffin
First Posted: Apr 23, 2014 10:12 AM EDT
Early in our Earth's history, vast outpourings of lava from deep within our planet accompanied the breakup of continents. Now, though, researchers have found that these massive outpourings may not be as deep as once thought, and could have originated nearer to the surface rather than deep within the mantle.
In order to learn more about the massive lava flows which accompany continental rifting and continent breakup, the researchers conducted field studies on the African tectonic plate. The Great Rift Valley of East Africa in particular provided a snapshot of how a continent can be torn apart. In fact, the ancient African outpouring that occurred about 30 million years ago poured out an estimated 350,000 cubic kilometers of lava, which is comparable to twice the amount of water in all the world's lakes.
"For decades, there's been a big debate as to where the lavas from this massive outpouring came from," said Tyrone Rooney, one of the researchers, in a news release. "Did they emit from deep within the Earth? Or was there some contribution from shallower sources? Our paper shows that some lavas came from within the African tectonic plate itself."
While much of the lava is probably from deep sources, the researchers found some parts of the tectonic plate that had melted to form an unusual group of lavas in Ethiopia. The rocks that were artifacts from this ancient outpouring actually had chemical signatures of materials found in the lithosphere and were different from most of the other rocks in Ethiopia. Not only that, but the researchers found that these Ethiopian samples matched rocks collected from other distant regions-Arabia, Jordan, Egypt and Sudan. This suggested that some of the ingredients that supply the massive outpourings have a shallow source that is tapped as the continents split apart.
"We're interested in this because these massive outpourings happen around the same time continents break apart, create new oceans and affect the planet and the environment on a global scale," said Rooney in a news release. "So knowing the source of the lava gives us insights into a process that we still know little about."
The findings reveal that these massive outflows didn't all occur from deep within the Earth. Instead, there are shallower sources available. This, in turn, shows a little bit more about our planet's history.
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First Posted: Apr 23, 2014 10:12 AM EDT
Early in our Earth's history, vast outpourings of lava from deep within our planet accompanied the breakup of continents. Now, though, researchers have found that these massive outpourings may not be as deep as once thought, and could have originated nearer to the surface rather than deep within the mantle.
In order to learn more about the massive lava flows which accompany continental rifting and continent breakup, the researchers conducted field studies on the African tectonic plate. The Great Rift Valley of East Africa in particular provided a snapshot of how a continent can be torn apart. In fact, the ancient African outpouring that occurred about 30 million years ago poured out an estimated 350,000 cubic kilometers of lava, which is comparable to twice the amount of water in all the world's lakes.
"For decades, there's been a big debate as to where the lavas from this massive outpouring came from," said Tyrone Rooney, one of the researchers, in a news release. "Did they emit from deep within the Earth? Or was there some contribution from shallower sources? Our paper shows that some lavas came from within the African tectonic plate itself."
While much of the lava is probably from deep sources, the researchers found some parts of the tectonic plate that had melted to form an unusual group of lavas in Ethiopia. The rocks that were artifacts from this ancient outpouring actually had chemical signatures of materials found in the lithosphere and were different from most of the other rocks in Ethiopia. Not only that, but the researchers found that these Ethiopian samples matched rocks collected from other distant regions-Arabia, Jordan, Egypt and Sudan. This suggested that some of the ingredients that supply the massive outpourings have a shallow source that is tapped as the continents split apart.
"We're interested in this because these massive outpourings happen around the same time continents break apart, create new oceans and affect the planet and the environment on a global scale," said Rooney in a news release. "So knowing the source of the lava gives us insights into a process that we still know little about."
The findings reveal that these massive outflows didn't all occur from deep within the Earth. Instead, there are shallower sources available. This, in turn, shows a little bit more about our planet's history.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone