Study finds magma deep below Pacific Ocean

U.S. scientists say studies of magma deep beneath a Pacific Ocean seafloor volcano are yielding clues to how new seafloor is created. Since the plate tectonics theory of the 1960s scientists have known new seafloor is created in the world's major ocean basins at linear chains of volcanoes known as mid-ocean ridges, but have been unsure where the erupting magma comes from. Researchers at Scripps Institution of Oceanography at the University of California, San Diego, say their capturing of a unique image of a site deep in the Earth where magma is generated could lead to a better understanding of the process. Using electromagnetic technology, the researchers mapped a large area beneath the seafloor off Central America at the northern East Pacific Rise, a seafloor volcano located on a section of the global mid-ocean ridges that together form the largest and most active chain of volcanoes on Earth. The cross-section area of the melting region they mapped would rival the size of San Diego County, they said. "Our data show that mantle upwelling beneath the mid-ocean ridge creates a deeper and broader melting region than previously thought," Scripps geophysicist Kerry Key said. "This was the largest project of its kind, enabling us to image the mantle with a level of detail not possible with previous studies." The marine electromagnetic technology behind the study was originally at Scripps in the 1960s and has been used by the energy industry to map offshore geology as an aid to exploring for oil and gas reservoirs. Scripps researchers said were pleased at how it has now been used to advance the science of plate tectonics. "We have been working on developing our instruments and interpretation software for decades, and it is really exciting to see it all come together to provide insights into the fundamental processes of plate tectonics," Scripps geophysicist Steven Constable said. "It was really a surprise to discover that melting started so deep in the mantle -- much deeper than was expected."