Ocean floor image of study site reveals unusual setting where volcanic ridgeline separates into two overlapping ridges

Durham, NC - A Duke University-led expedition studying an expanding part of the bottom of the Pacific Ocean will be sharing its experiences on a website presented by Duke's Nicholas  School of the Environment and Earth Sciences.

From March 25 to April 21, a research ship carrying scientists, graduate students and middle- and high school educators will be positioned over an "overlapping spreading center" (OSC) off the western coast of Central America where molten rock is repaving the sea floor.

They will be using a robotic underwater vehicle named Jason to study this geologically unusual region at 9 degrees, 03 minutes North, known as the 903 OSC for short. Jason is equipped with mechanical arms and grasping claws to pick up rock samples, and it can make continuous digital photographs and videos of its surroundings and activities.

The 903 OSC was previously probed with sound waves to reveal the outline of a subterranean "magma chamber," an irregularly shaped lens of molten rock overlying a wider and deeper region of hot rock and melt.

The researchers working aboard the research ship -- the RV Atlantis, based at Woods Hole, Mass. -- will be looking for evidence of the pathways through which molten rock finds its way to the ocean floor above.

"There have been all sorts of assumptions about what you see at the surface and in the magma chamber deep in the crust," said Emily Klein, the Duke geology professor who will serve as the expedition's chief scientist. "But we have not been able to test these assumptions. Some scientists have thought that where the melt lens is widest, there is going to be abundant lava flow on the surface above it. One of our main goals will be to test this idea."

The 903 OSC is one of five such geologic areas located along the East Pacific Rise, an underwater mountain chain that stretches from the Gulf of California south almost to Antarctica. New ocean floor is made all along this chain when the crust opens up and spreads apart, releasing molten lava.

Because a large magma chamber system has been documented under parts of the 903 OSC, Klein is hoping the expedition will also discover a hydrothermal vent system at the site. These ocean-floor vents allow mineral-laden superheated water to well up through chimney-shaped geological formations, supporting unusual forms of marine life in the vicinity.

Educators on the Atlantis expedition will be testing out a new project to let middle- and high school students communicate with scientists and explore data from ashore. The web-based project will become part of a worldwide hands-on education and science program known as GLOBE, for "Global Learning and Observations to Benefit the Environment." The expedition is being funded by the National Science Foundation; GLOBE is supported by NSF and NASA.