Close-up of Subsea 'Lost City'

It may not be Atlantis, but this field of hydrothermal vents sure resembles a lost city.  

"Lost City is truly one of the most remarkable places on our planet. Its serendipitous discovery shows that there is still much left to be learned about our oceans and the life they sustain," said NOAA scientist Debbie Kelley.

The image above is of the summit of the 200-foot tall carbonate chimney named Poseidon. The white chimney in the foreground is active and venting fluids at temperatures of 131 degrees Fahrenheit. As chimneys get older, they turn grayish brown like the one in the background.

Kelly and her colleagues discovered the field of hydrothermal chimneys in 2000, the first of its kind to be discovered. Unlike "black smoker" chimney vents, the fluid venting at Lost City is not driven by heat from cooling volcanoes, but from heat when seawater reacts with rocks below the field.

Fluids in black chimney smokers are hot (reaching more than 700 degrees F), but at Lost City vents are cooler (less than 200 degrees F). Unique life forms make their home in the Lost City, living without sunlight and thriving on methane and hydrogen gases given off during alteration of the rocks.

The field - about 1,300 feet long and 1,000 feet wide at a depth of 2,600 feet - is on top of the Atlantis Massif, part of an underwater chain of mountains that zig-zag around the planet. There are more than 30 active and inactive chimneys in the field, which has been active for nearly 30,000 years.

The ocean crust the vents grow from is about 1.5 million years old. "Because of its unique chemistry and geologic setting, Lost City may be one of our closest analogues to hydrothermal systems active during early formation of oceans on Earth and other planets," said Kelley.

The July 23 through August 1 mission is financially supported and coordinated by NOAA.

--Bjorn Carey

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Credit: NOAA / University of Washington