Towering sea spires amaze researchers in Atlantic

By JOSEPH VERRENGIA

Associated Press

Oceanographers patrolling the mid-Atlantic in a miniature research submarine have stumbled onto a spectacular deep-sea garden of hot springs and towering spires they nicknamed the “Lost City.”

“They rival redwood trees in height,” said Debbie Kelley, a University of Washington expert on hydrothermal vents. “Above your head, the flanges trap reflecting pools of water. They make perfect mirror planes and look like upside-down waterfalls.”

The scientists spotted the formations on Dec. 4 more than 3,200 feet below the frigid, stormy Atlantic during a monthlong expedition to explore a submerged mountain.

The scientists have posted their findings on a Web site, earthguide.ucsd.edu,c but have had little contact with onshore colleagues. They are scheduled to return to Woods Hole, Mass., today aboard the research ship Atlantis.

Understanding the peculiarities of the Lost City formations may shed light on Earth’s geological development and the origins of simple life, as well as conditions on Jupiter’s moon Europa and elsewhere around the solar system, they said.

They said some of the ghostly white mineral formations soar 180 feet – the tallest undersea spires ever seen. Collectively, they cover an area larger than a football field on the flanks of a 14,000-foot mountain known as the Atlantic massif at 30 degrees north latitude.

The formations have risen over eons as the result of the accumulation of minerals dissolved in hot water bubbling up through fissures known as thermal vents. They occur where plates in the Earth’s crust collide and grind.

Gleaming against the pitch-black ocean depths, some of the pinnacles resemble stalagmites in a cave, while others look like dribble-sand castles on the beach. Ledges, or flanges, of the crusty, feathery crystals jut from the spires like mushrooms.

“If this were on land,” Duke University geologist Jeff Karson said, “it would be a national park.”

Until now, ocean scientists believed they had seen all that seafloor vents had to offer in previous expeditions.

But the Lost City contains scientific surprises, besides a stunning appearance.

For starters, researchers said, it occurs on a piece of the Earth’s crust that is about 1 million years old. Most vents occur at points where the crust is much younger.

The water from the vents is relatively cool at 160 degrees. The structures are composed of carbonate minerals and silica. Most seafloor hot springs deposits are formed by iron and sulfur-based minerals.

Rocks in the rugged area were formed in the Earth’s hot mantle and pushed several miles up to the seafloor along active faults.

Unlike vents in the Pacific, the mid-Atlantic vent field shows relatively little complex life. The scientists saw dense, floating mats of microorganisms but little else.

Researchers using the submarine’s robotic equipment took samples of microbes and vent fluids for DNA analysis.

“Why we did not see clams, mussels or shrimp is a mystery to me,” UW scientist Kelley said. “The microorganisms that live within these fields may be very different.”

The formations were initially spotted after midnight in a video image supplied by an unmanned research vehicle Argo that is towed at the end of a two-mile cable by the Atlantis.

A day later, researchers explored the area in the minisub Alvin.