New crust being formed in novel way

Scientists at the Woods Hole Oceanographic Institution (WHOI) have observed ocean crust forming almost ten times farther away from an active ocean ridge than previously recorded
Ocean crust is usually formed as magma bubbles up through volcano-like openings in a narrow (about five-kilometre-wide) zone along the boundaries between two plates that are pulling away from each other. Working at the Guaymas Basin in the Gulf of California, the WHOI scientists used a sound-wave-emitting air gun, side-scan sonar and ocean-floor cameras to confirm that magma was forming sills within the top one or two kilometres of the thick layer of sediment that fills the basin, about 50 kilometres away from the plate boundary.

The process has important implications for the local marine life, as well as the carbon cycle. The heat from the rising magma releases nutrient-rich fluid from within the sediments that is feeding communities of sea creatures similar to those found around vent sites near deep-water mid-ocean ridges. It also causes the release of significant amounts of carbon from the sediments around ten times more carbon dioxide and methane than a similar volume of volcanic rock emerging from a vent.

The researchers suspect that the phenomenon is not restricted to the Gulf of California, but is almost certainly taking place in other sites.

January 2011

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