Fluid samples taken from underwater vents on the Juan de Fuca Ridge coupled with the finding of a body of molten rock suggest that contact with magma, not movement on faults associated with an ocean floor earthquake, caused a rapid change in the chemistry of the vents off of the California/Oregon coast, according to scientists from the University of Washington and, the National Oceanic and Atmospheric Administration (NOAA). NOAA is an agency of the U. S. Department of Commerce.

The findings, described in a paper by Marvin D. Lilley and Eric J. Olson of the School of Oceanography, University of Washington, John Lupton of the Pacific Marine Environmental Laboratory (PMEL), and David A. Butterfield of the Joint Institute for the Study of the Atmosphere and Ocean, University of Washington and PMEL, will be published in the April 24 issue of the science journal Nature.

“This is why ocean exploration and observation are important,” said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. “There findings help to further our understanding of how planet earth works.”

Samples were collected in 1999 using the deep-sea vehicle Alvin, which is owned by the U.S. Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Mass.

“This makes us reexamine our ideas about the heat source driving the hydrothermal system in that area,” said John Lupton, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory in Newport, Oregon.

“We looked at samples from five of the vents - Hulk, Dante, Bastille, Puffer, and Sully,” said Lilley. “The data show an increase in carbon dioxide and helium, which are usually found in areas with active magma chambers, such as the Axial volcano off of the Oregon coast, the Loihi seamount in Hawaii, and an eruptive area on the East Pacific Rise.”

Those spikes along with new data collected in July 2002 indicating a body of magma molten rock about 1.5 miles (2.3 km) deep below the ocean floor, have scientists rethinking the vent field’s heat source.

Volcanic events, rather than earthquakes alone, can have rapid and profound effects on the fluid that comes up, Lilley and co-authors reported. There are changes in temperature, the ratio of water and rock, and the concentration of gases. During seismic events, these changes happen much more slowly.

First discovered in 1977, underwater vents are places where hot water flows into the ocean after being heated in the earth’s crust. Unusual sea life, such as tubeworms, crabs, and clams, are often attracted to the chemical soup that is spewed up through the vents. NOAA’s VENTS Program, which is part of the Pacific Marine Environmental Laboratory, conducts research on the impacts and consequences of submarine volcanoes and hydrothermal venting on the global ocean.

The NOAA Office of Oceanic and Atmospheric Research is dedicated to enhancing economic security and national safety through research to better understand weather and climate-related events and to manage wisely our nation's coastal and marine resources.

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