Using one of the deepest-diving submersibles in the world, scientists hope to begin exploring the sea floor off Northern California this week to investigate the extent of minerals deposited there by hot water seeping upward through sediments.
The scientific effort is intended to map out deposits of copper, zinc and precious metals such as silver within the only area in the nation's coastal Exclusive Economic Zone where stores of these minerals are thought to exist.
The ambitious plan for a month of dives on an undersea formation called the Gorda Ridge also represents a milestone in a 4-year federal effort to turn the San Diego-based Sea Cliff submersible from a U.S. Navy workhorse into a regular resource for civilian oceanographers.
Chance to Prove Mettle
The scientific community's response to a partnership with the military has been lukewarm, and the expedition is giving the Navy its best chance to prove the mettle of the Sea Cliff and its new mother ship to skeptical scientists.
This is especially important to the Navy after a disappointing 1986 trip to the same area, during which the Sea Cliff repeatedly could not be launched because
its inadequate mother ship needed very calm seas.
Tucked into a shelter aboard its new, more versatile mother ship, the Laney Chouest, the 31-foot Sea Cliff left port in San Diego Friday for the spot 150 miles west of Eureka where it now is waiting to dive.
This time around, the three-person Sea Cliff was to have begun diving Monday, but 35 m.p.h. winds and 20-foot seas prevented launching the submersible so far this week, said John Smith, co-chairman of the group overseeing the research effort, in a phone interview from the ship at sea.
The civilian ship Laney Chouest, leased by the Navy this spring, is carrying a crew of about 50, divided roughly equally among three groups: the ship's civilian crew, the scientists and the Navy crew for the submersible itself.
"This is very different. It's weird," said Lt. Cmdr Michael R. Popovich, officer in charge of Sea Cliff, of the military-civilian partnership. His comments came during an interview last week, shortly before the ship left its berth at the 32nd Street Naval Station.
Exploring Gorda Ridge
Indeed, the effort to explore an undersea mountain range known as the Gorda Ridge since 1984 has drawn together an unusual conglomeration of federal officials, officials of California and Oregon, business people and scientists. Meeting under the auspices of an umbrella group called the Gorda Ridge Technical Task Force, which is financed by the U. S. Minerals Management Service, they have met regularly to coordinate exploration on the Gorda Ridge.
The odd combination continues this year. The task force is using $200,000 of Minerals Management Service money to pay for research projects and its own administrative expenses, but the Navy is providing the submersible free.
At a rate of $5,000 a day for dive time--the rate the Navy has suggested in the past for Sea Cliff use--that amounts to at least a $120,000 "loss leader" by the Navy to prove the submersible's scientific value. The nation's premier research submersible, the Alvin, costs $22,000 a day to use.
The area the researchers are targeting is a vast underwater mountain range known as the Gorda Ridge, which stretches 120 to 150 miles off the West Coast from central Oregon to Eureka in Northern California. On land, the craggy valleys of the Gorda Ridge system would rival the Grand Canyon in scale.
It is an area where two giant "plates" of the Earth's crust are spreading apart, allowing water to sink through cracks and come into contact with hot volcanic rocks. The heated water leaches minerals from the volcanic rocks, then rises and redeposits them on the ocean floor when it hits the cold ocean waters. On bare rocks such as are the norm in the northern portion of the Gorda Ridge, the minerals can build up as tall "chimneys." Through sediments, the hot water percolates upward to form broad blankets of minerals within the sediments.
Research in 1986 indicated that this process in the area 150 miles west of Eureka may have deposited such blankets over many square miles of a heavily sedimented valley at the southern end of the Gorda Ridge, called the Escanaba Trough.
The extent of the deposits, the quality of the ore and whether it will ever be economically feasible to mine it from under more than 10,000 feet of water remains uncertain. Still, the Minerals Management Service wants to document the ore deposits as a potential future resource within the EEZ that President Reagan declared in 1983.
In 1984, Secretary of the Navy John F. Lehman Jr. announced a major initiative to turn the Sea Cliff and another San Diego submersible, the Turtle, into scientific resources, said Lt. Cmdr. William Grella, deep submergence commander for Submarine Development Group 1 in San Diego, which operates Sea Cliff.
But, since then the only taker on the offer has been the Gorda Ridge task force, Grella said.
Scientists say they have been concerned both about the submersible's availability and its capabilities.
For instance, while the Sea Cliff was being readied for the current trip, it had to be pulled off to search for the remains of a Navy helicopter that crashed off San Francisco July 19. Grella said a similar diversion is always possible during a scientific expedition, but every effort will be made to avoid it.
"The Navy would not want to cut off its nose to spite its face," Popovich said. "It would have to be a problem that none of our other assets could handle."
Also, oceanographers say that, despite its upgrading since 1983, the submersible remains less useful than the much-used Alvin. That is despite the fact that Alvin, operated by Woods Hole Oceanographic Institution in Massachusetts, dives to only two-thirds the depth of the 20,000-foot Sea Cliff. Only one other small submersible, operated by the French, goes as deep as Sea Cliff.
Most notably, Sea Cliff's robotic manipulator arms for taking samples are not as versatile as Alvin's, said John Edmond, a veteran Alvin diver and an oceanographer at Massachusetts Institute of Technology.
"We're all sitting to wait and see," Edmond said of the Sea Cliff's research trip. "If they do come up with a reliable operation and they do come up with real scheduling procedures and if they put on more advanced manipulators, I certainly would be interested in using it."
Using the submersible Alvin earlier this summer, researchers led by Edmond found 220-degree Celsius water venting over a 300-foot-square area of the Escanaba Trough. The area was covered by tube worms and mussels similar to those that, at other hot-water vents, use hydrogen sulfide in the vent waters for energy, he said, and there were indications of other areas with similar vent patterns.
So far, the only other interest in using the Sea Cliff for science has come from Peter Lonsdale of Scripps Institution of Oceanography, Grella said. Lonsdale has done research with the sub in the past and wants to use it to study the geology of the ocean floor near the Galapagos Islands, Grella said.
For some oceanographers, another issue in working with the Navy has been its concern for security and its military-style rules.
For instance, only scientists with security clearances can view the best available maps of the sea floor. The Gorda Ridge trip organizers had to obtain special permission from the Navy for women to be allowed in the scientific party.
Smith, a Minerals Management Service geologist and one of three co-chairs of the Gorda task force, said he was operating as "a guest on board of a Navy vessel" during the expedition.
The Sea Cliff's dives over the next month will be divided between the southern and northern parts of the Gorda Ridge system, with 14 dives planned in the south and 10 dives in the north. Chief scientist aboard the first leg of the trip is Mark L. Holmes of the U.S. Geological Survey. Chief scientist for the second half will be Peter Rona of the National Oceanic and Atmospheric Administration.
Two marine biology graduate students at Scripps Institution of Oceanography, Scott France and Michel Boudrias, will be assisting with biological experiments during the dives.