March 22nd, 2013 by Joshua S Hill
Scientists have for decades attempted to solve the ‘how’ of plate tectonics: how they move across the Earth’s mantle. Studies have shown in the past that dissolved water in mantle minerals results in a more ductile mantle that would facilitate tectonic plate motions, but clear images and data required to confirm such a theory have been beyond our grasp.
However, scientists from Scripps Institution of Oceanography at UC San Diego have found a layer of liquefied molten rock in Earth’s mantle that they believe may be acting as lubricant for the tectonic plates.
Beyond simply being a fascinating study of pate tectonics, such a discovery — if proven to be true — has the ability to better improve our understanding of volcanism and earthquakes; understanding that could theoretically save thousands, if not millions of lives.
Scripps scientists along with a representative of Woods Hole Oceanographic Institution took part in a 2010 expedition aboard the US Navy-owned and Scripps operated research vessel Melville, where they deployed a vast array of seafloor instruments that record natural electromagnetic signals to map features of the crust and mantle.
Images captured by the instruments revealed magma in a surprising place.
“This was completely unexpected,” said Kerry Key, an associate research geophysicist in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps. “We went out looking to get an idea of how fluids are interacting with plate subduction, but we discovered a melt layer we weren’t expecting to find at all—it was pretty surprising.”
“Our data tell us that water can’t accommodate the features we are seeing,” said Samer Naif, a Scripps graduate student and lead author of the paper. “The information from the new images confirms the idea that there needs to be some amount of melt in the upper mantle and that’s really what’s creating this ductile behavior for plates to slide.”
“One of the longer-term implications of our results is that we are going to understand more about the plate boundary, which could lead to a better understanding of earthquakes,” said Key.
They now hope to further their understanding by determining the source of magma discovered.
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