July 27, 2003

The Lost City and the Origins of Life

The Atlantis Massif, site of the Lost City

Mysterious and haunting discoveries emerge almost weekly not from outer space but from the depths of our own oceans. One that I find especially chill inducing concerns the structures at the top of the Atlantis Massif:Hydrothermal Vent Systems Could Have Persisted Millions Of Years, Incubated Life

The staying power of seafloor hydrothermal vent systems like the bizarre Lost City vent field is one reason they also may have been incubators of Earth's earliest life, scientists report in a paper published in the July 25 issue of Science.

Discovered just 2 years ago during a National Science Foundation-funded expedition in the mid-Atlantic Ocean, Lost City has the tallest vents ever seen; the 18-story behemoth at the site dwarfs most vents elsewhere by at least 100 feet.

Water is circulated through the vent field by heat from serpentinization, a chemical reaction between seawater and the mantle rock on which Lost City sits, rather than by heat from volcanic activity or magma, responsible for driving hydrothermal venting at sites scientists have been studying since the early 1970s.

Spire of the Lost City

The daily journals of the Lost City Expedition can be found online with entries such as this one:

We drove along the cliff face for about an hour, and only saw veins, carbonate rubble, and steep slopes of serpentinite. Because of this, Debbie decided that we should go further up the cliff, to trace where the carbonate was coming from.When we reached the top of the cliff, we found a broad, flat area that was covered in carbonate, and was the probable source for the pieces we found further down the slope. We grabbed a few samples to finish our exploration to the east. Pat flew us back to Lost City, and we circled around Poseidon, the huge structure in the middle of the field. We were on the lookout for an active vent structure, called the Beehive, that the previous Alvin dive had knocked over. We managed to find the site of venting and took some water samples from this vent. Then we searched until we found the shattered remains of the Beehive. While we were doing this, I was looking out the window at Poseidon. It's so big that I couldn't see the top, the bottom, or around the corner. It is simply unbelievably huge. After I gawked at it for awhile, we still had a little time left to explore to the west of Lost City. Along the western cliff, we saw beautiful outcrops of serpentinite, topped by breccias and carbonate...

Posted by Vanderleun at July 27, 2003 10:54 PM
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