World's deepest known undersea volcanic vent found

[April 20, 2010]  LONDON (AP) -- Scientists using a remote-controlled submarine have discovered the deepest known volcanic vent and say the superheated waters inside could contain undiscovered marine species and perhaps even clues to the origin of life on earth.

Experts aboard the RRS James Cook said they found the underwater volcanic vent more than three miles (five kilometers) beneath the surface of the Caribbean in an area known as the Cayman Trough, a deep-sea canyon that served as the setting for James Cameron's underwater thriller "The Abyss."

Geologist Bramley Murton, the submersible's pilot, said exploring the area was "like wandering across the surface of another world," complete with spires of multicolored mineral deposits and thick collections of fluorescent blue microorganisms thriving in the slightly cooler waters around the chimneys.

The scenes "were like nothing I had ever seen before," Murton said.

Volcanic vents are areas where sea water seeps into small cracks that penetrate deep into the earth's crust -- some reaching down more than a mile (two kilometers.) Temperatures there can reach 750 degrees Fahrenheit (400 degrees Celsius), heating the water to the point where it can melt lead.

The blazing hot mineral-rich fluid is expelled into the icy cold of the deep ocean, creating a smoke-like effect and leaving behind towering chimneys of metal ore, some two stories tall. The spectacular pressure -- 500 times stronger than the earth's atmosphere -- keeps the water from boiling.

The environment in volcanic vents may appear brutal: the intense heat and pressure combines with toxic metals to form a highly acidic undersea cocktail. But vents host lush colonies of exotic animals such as blind shrimp, giant white crabs, and even large red-lipped tubeworms whose lack of any apparent digestive system once left scientists scratching their heads.

At the base of this ecosystem present are chemical-eating bacteria who draw on the hydrogen sulphide and methane erupting from the vents to make food.

"Although those are lethally hostile conditions for surface-dwellers like us, life exists at all depths in the oceans, right down to the bottom of the deepest trenches," said marine biologist Jon Copley in an e-mail interview from the James Cook.

"We're still figuring out how."

Because the vent area is nearly half a mile deeper than any previously discovered, scientists speculate that it could be the hottest ever found. Study of the vent could yield a variety of new insights into the history of the ocean, the physics of so-called "supercritical fluids" -- liquids so hot they act like gasses -- and the chemical makeup of the deep ocean.

Most tantalizing is the prospect that the expedition, led by geochemist Douglas Connelly of Britain's National Oceanography Center, could also reveal a variety of new life forms specially adapted to the Trough's punishing environment.

"The deep sea is full of surprises," a statement posted to the expedition's Web site said. "We may find species unlike any seen before. The Cayman Trough may be like (Arthur) Conan Doyle's 'Lost World,'" a novel that imagines an area populated by prehistoric monsters hidden deep in the Amazon.

Other scientists said they were excited by the discovery.

"I'm extremely curious to see and hear what they have found there in terms of biology," said Maya Tolstoy, a marine geophysicist at Columbia University's Lamont-Doherty Earth Observatory.

This vent and others like it are also of interest to scientists because of the role some scientists believe they played in the creation of life on earth.

Copley said it has been theorized that life may have originated in similar environments early in the Earth's history -- in part because the microorganisms found in deep-sea vents appear close to some of the Earth's most ancient organisms.

Still, Copley said, "there are a lot of assumptions in that deduction."

"The origin of life is one of the greatest unanswered questions in science, and at the moment vents are one of the contenders, but they are certainly not the only one."

The Cayman Trough vent was discovered on April 6, according to Copley, who said the team used a cube-shaped submersible linked to the ship by three miles (five kilometers) of cable. Copley said the discovery had been three years in the making and built on the work of a U.S.-led survey of the area last year.

He said the find illustrated how little was known about what lurks at the bottom of the sea, a sentiment backed by Tolstoy.

"We know more about the surface of the Moon and Mars than we do about our own planet because two-thirds of our planet is covered by ocean making it very hard to explore," she said.

"We've only seen a tiny fraction of the deep-sea floor so there are undoubtedly many more vents and other amazing things to discover."

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On the Net:

RRS James Cook: http://www.thesearethevoyages.net/

[Associated Press; By RAPHAEL G. SATTER]

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