March 15, 1995 Contact: Pamela Donegan or Robert Irion (408/459-2495)
UC SANTA CRUZ MAKES ITS MARK IN OCEAN DRILLING
FOR IMMEDIATE RELEASE
SANTA CRUZ, CA--Three miles under the whitecaps of the world's oceans, large chapters of earth's history are engraved in stone. Sediments that settled millions of years ago on the seafloor recorded everything from temperature change to the slow waltz of drifting continents. Geologists would have a field day--if they could. Alas, the crushing presence of all that water makes ordinary geological sampling impossible. But there is a way to reach those rocks without jeeps, shovels, or hammers: You can use a big seagoing drill.
Systematic scientific drilling began 27 years ago with the Deep Sea Drilling Program (DSDP) and continues today as the Ocean Drilling Program (ODP), an internationally financed operation run by Texas A&M University. The flagship of ODP is the 470-foot-long JOIDES Resolution, commissioned by the Joint Oceanographic Institutions for Deep Earth Sampling. It is no ordinary ship. Sporting a drilling derrick one-fifth the height of the Eiffel Tower, the ship has more than five miles of drill pipe. Beneath its deck are laboratories brimming with everything from microscopes to cryogenic magnetometers. Thus equipped, the world's earth and marine scientists have been gradually piecing together the story of the planet's many face-lifts and climate shifts.
Many of these pelagic planetary detectives hail from the University of California, Santa Cruz. "The level of our involvement with ocean drilling is really astounding for a place this size," says professor of earth sciences Eli Silver. At least twenty faculty and graduate students have signed on--some, more than once. They are undeterred by the rigors of eight weeks out of sight of land, twelve- hour work shifts, cramped quarters, and a woeful lack of lettuce.
J. Casey Moore, also a professor of earth sciences, has been out seven times--three times as one of the co-chief scientists directing drilling operations. He readily points out the unique contributions of the program. "Literally, until about 40 or 50 years ago, the ocean floor offshore was completely unknown," he says. "Now, with ocean drilling, we can get beneath it."
Moore credits ocean drilling with some of geology's most exciting discoveries. The best example, he says, is the evidence that rocks gradually increase in age the further they are from mid-ocean ridges. This confirmed a theory that the earth constantly gives birth to oceanic crust at these seams. Scientists now know that newly formed sheets travel away from the center like conveyor belts. At continental edges, these thin crustal plates have nowhere to go, and they dive into the planet, melting under the pressure of the overriding continental plates. This process is integral to the large- scale motions of the earth's crust known as plate tectonics.
Moore's own research has taken him to several plate boundaries, where the pressure of the collision between seafloor and continental plate cracks surrounding rock layers. "I'm into plate boundary faults," he says. "They're exciting. They produce big earthquakes." This past summer he and two UCSC doctoral students, Gretchen Zwart and Harold Tobin, drilled at a plate boundary off Barbados. There, they documented a fluid channel, like an underground river, running between the Caribbean plate and the diving Atlantic seafloor. He found a similar phenomenon in 1992 off the Oregon coast. Such channels provide clues about plate-boundary dynamics, he says, because the water pressure in the channels increases with the force of the plate collision. Greater forces indicate a greater likelihood of earthquakes at the fault. "If we can monitor these fluids, potentially we could plug into the earthquake cycle," he says.
Eli Silver also studies continental margins, especially in areas where plate collisions are raising mountains. He is a veteran of marine geophysical expeditions and sailed once as co-chief scientist aboard the JOIDES Resolution. Now, he is preparing for another cruise to Costa Rica in 1996. Like Barbados, Costa Rica is an area where one plate of the earth's crust rides over the top of another like a bulldozer. By drilling there, Silver hopes to measure the proportion of ocean sediments carried deep into the plate margin versus those that stay plastered at the edge. This diving material concerns scientists because it often returns to the surface in the form of volcanic eruptions.
Margaret Delaney, associate professor of marine sciences, pursued a different type of research on her one voyage with ODP. Using a vice to squeeze sediment cores, she measured the chemistry of the water trapped between the grains. She found that over millions of years, fossilized plankton lose some of their minerals into that broth. Because most scientists did not realize how much leaching occurred, Delaney's work may change the way that submarine fossils are used to trace the ocean's chemical history.
Another drilling program participant, assistant professor of earth sciences James Zachos, studied ancient climates during his cruises in 1985, 1988, and last spring. Zachos says his most important discovery occurred during drilling in the southern Indian Ocean. There, he found evidence that ice sheets first appeared on Antarctica 40 million years ago, some 25 million years earlier than previously thought. This has prompted scientists to revisit their theories of how ice ages begin. Originally, they believed that large ice sheets could exist only when the poles turned cold. However, the presence of the ice blanket on Antarctica during a relatively warm time in earth's history indicates that other factors must have triggered global glaciation.
Ocean drilling is not all about individual research, though. "It's an incredibly successful international program," says Moore. "It's phenomenal the level of cooperation it fosters." Even the occasional language barrier or personality quirk doesn't interfere with the camaraderie, Moore says. Silver agrees, but adds: "After two months at sea, you're really ready to get off the ship."
Editor's Note: For further information, contact any of the following
researchers:
Margaret Delaney: (408) 459-4736 or
This release is also available on UC NewsWire, the University of
California's electronic news service. To access by modem, dial (209)
244-6971.
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