Mineral-Rich Plume Found Deep in the Pacific

A “very spectacular” plume of mineral-rich, warm water was discovered deep in the Pacific Ocean off the Oregon coast by scientists who believe that they have stumbled across a fundamental process of nature.

At the annual meeting of the American Geophysical Union here Tuesday, the researchers said they found the plume while studying a field of small, hot vents on the ocean floor. They said the plume was unlike anything seen before.

It measured more than 12 miles in diameter and apparently was caused by hot gases and lava spewing out of a crack in the ocean floor, said Edward Baker, an oceanographer with the National Oceanic and Atmospheric Administration.

Baker was with a team of scientists aboard the agency’s research vessel, Discover, when they came across the plume. They were studying a field of smaller hot vents along the Juan de Fuca Ridge, a sea-floor ridge that marks the edge of two tectonic plates--the giant land masses that float on the Earth’s molten mantle.

It is in that area of “sea-floor spreading,” where the tectonic plates are separating, that the much smaller hot vents, called “black smokers,” release gases and lava that well up from deep within the Earth. These vents have been widely studied in recent years because of the exotic plant and animal life found nearby.

While studying these vents in August, instruments aboard the research vessel began acting strangely, Baker said at a press conference. The instruments recorded a twentyfold increase in minerals and the slight warming of a huge area.

Baker said they rechecked their instruments and then stayed in the area for six days--until the plume gradually disappeared. By that time they had determined that the plume was enormous, measuring 12 miles in diameter and about half a mile deep.