Now a North American team of scientists has documented for the first time a new phenomenon the creation of a void in the seafloor that draws in rather than expels surrounding seawater.

They report their discovery in the July 15 issue of the journal Nature.

Oregon State University oceanographer Robert Dziak said the discovery is important because it adds a new wrinkle to scientific understanding of seafloor spreading, the fundamental process of plate tectonics and the creation of ocean crust. Dziak has a dual appointment with the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory.

"Just when you think you're beginning to understand how the process works, there's a new twist," Dziak said. "There was an episode of seafloor spreading on a portion of the Juan de Fuca Ridge that was covered with about a hundred meters of sediment and what usually happens in that case is that lava erupts onto the ocean floor and hot fluid is expelled into the water.

"In this case, though, it actually drew water down into the subsurface, which is something scientists have never before observed," he said.

The research team included Earl Davis, of the Geological Survey of Canada's Pacific Geoscience Centre; Keir Becker, from the Rosenstiel School of Marine and Atmospheric Science at the University of Florida; Dziak; and John Cassidy, Kelin Wang and Marvin Lilley of the University of Washington.

Dziak said the researchers think the seafloor spreading caused the ocean crust to dilate, increasing the pore space much like a sponge. "It's like an anti-plume," he said. "Instead of sending materials from within the Earth to
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Contact: Robert Dziak
robert.dziak@oregonstate.edu
541-867-0175
Oregon State University
14-Jul-2004