March 21, 2013
Magma Could Be Earth’s Natural Lubricant For Tectonic Plate Movement
redOrbit Staff & Wire Reports - Your Universe Online
Scientists from the University of California, San Diego´s (UCSD) Scripps Institution of Oceanography (SIO) have discovered a liquefied layer of molten rock in the planet´s mantle — a substance which could be acting as a lubricant of the sliding motions of the Earth´s tectonic plates.
The magma layer was discovered at the Middle America trench offshore Nicaragua during a 2010 expedition aboard the US Navy-owned research vessel Melville. Using several different types of seafloor instruments, the researchers recorded natural electromagnetic signals in order to map the crust and mantle.
In the process, they managed to locate magma in a most surprising location — a discovery which is detailed in the March 21 issue of the journal Nature.
“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,” he added.
The researchers used advanced seafloor electromagnetic imaging technology, pioneered at the Scripps Institution, in order to create a 15.5 mile thick layer of partially melted mantle rock beneath the edge of the Cocos plate at the point where it moves underneath Central America.
The forces and circumstances that allow Earth´s tectonic plates to slide across the mantle have been the subject of much scientific debate for years. Previous research has shown that dissolved water in mantle minerals resulted in a more ductile mantle, which would help facilitate tectonic plate motions.
However, previously there had been no images or data in order to prove or disprove that belief. Now, Key, lead author Samer Naif, and co-authors Steven Constable of SIO and Rob Evans of the Woods Hole Oceanographic Institution (WHOI) have made a discovery that they believe could help provide better understanding of the functions behind plate movement.
“Our data tell us that water can't accommodate the features we are seeing,” explained Naif, a Scripps graduate student. “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,” Key added.