Fehn to study volcanoes, ocean in Japan

"The oceans and the continents aren't separate, they have a relationship," said Fehn. "We once thought that the interaction was one-way, that the land eroded into the sea. But it may be that some of the ocean floor gets thrown back onto the land also."

When tectonic plates, the masses of earth that make up the continents and sea floor, collide with one another, one usually gets pushed beneath the other like a sports car jammed under an SUV. Oceanic plates are covered under miles of sediment that has accumulated over millions of years as sea life dies and drifts to the ocean floor. When this sediment-encrusted plate is jammed under a continental plate, volcanoes form on land--volcanoes that may be spewing out that same sediment that has been pushed miles and miles beneath them.

Fehn will start in Kyoto on April 1 and for six months will sample the fluids belched forth from Japanese volcanic islands and geothermal fields to test for an isotope called iodine-129. This isotope--present in abundance only in the ocean floor--allows scientists to determine the age of the ocean sediment by measuring how much of the radioactive iodine has decayed. If Fehn finds that it is being ejected from lava vents on land, it will provide strong support for the theory that much of what sinks to the bottom of the ocean may someday make an encore appearance on dry land.

The project is an expansion of work carried out by Fehn and graduate student Glen Snyder at two other subduction zones in Central America and New Zealand. Both projects are supported by the National Science Foundation.

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