Scientists find evidence of hydrothermal vents on seafloor near Antarctica

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Washington, March 4 (ANI): Scientists at Columbia's Lamont-Doherty Earth Observatory have found evidence of hydrothermal vents on the seafloor near Antarctica, formerly a blank spot on the map for researchers wanting to learn more about seafloor formation and the bizarre life forms drawn to these extreme environments.

Hydrothermal vents spew volcanically heated seawater from the planet's underwater mountain ranges-the vast mid-ocean ridge system, where lava erupts and new crust forms.

Chemicals dissolved in those vents influence ocean chemistry and sustain a complex web of organisms, much as sunlight does on land.

In recent decades, more than 220 vents have been discovered worldwide, but so far no one has looked for them in the rough and frigid waters off Antarctica.

From her lab in Palisades, New York, geochemist Gisela Winckler recently took up the search.

By analyzing thousands of oceanographic measurements, she and her Lamont colleagues pinpointed six spots on the remote Pacific Antarctic Ridge, about 2,000 miles from New Zealand, the closest inhabited country, and 1,000 miles from the west coast of Antarctica, where they think vents are likely to be found.

Two important facts helped the scientists isolate the hidden vents.

First, the ocean is stratified with layers of lighter water sitting on top of layers of denser water.

Second, when a seafloor vent erupts, it spews gases rich in rare helium-3, an isotope found in earth's mantle and in the magma bubbling below the vent.

As helium-3 disperses through the ocean, it mixes into a density layer and stays there, forming a plume that can stretch over thousands of kilometers.

The Lamont scientists were analyzing ocean-helium measurements to study how the deep ocean exchanges dissolved gases with the atmosphere when they came across a helium plume that looked out of place.

It was in a southern portion of the Pacific Ocean, below a large and well-known helium plume coming off the East Pacific Rise, one of the best-studied vent regions on earth.

But this mystery plume appeared too deep to have the same source.

Suspecting that it was coming from the Pacific Antarctic Ridge instead, the researchers compiled a detailed map of ocean-density layers in that region, using some 25,000 salinity, temperature and depth measurements.

After locating the helium plume along a single density layer, they compared the layer to topographic maps of the Pacific Antarctic Ridge to figure out where the plume would intersect.

The sites they identified cover 340 miles of ridge line - about 7 percent of the total 4,300 mile-ridge. (ANI)

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