Washington, July 25 : Scientists have found black hydrothermal vent fields inside the Arctic Circle, which are farther north than anyone has ever seen before.
According to Marvin Lilley, a University of Washington oceanographer, dissolved sulfide minerals that solidify when vent water hits the icy cold of the deep sea have, over the years, accumulated around the vent field in what is one of the most massive hydrothermal sulfide deposits ever found on the seafloor.
The cluster of five vents - one towering nearly four stories in height - are venting water as hot as 570 F.
The vents are located at 73 degrees north on the Mid-Atlantic Ridge between Greenland and Norway, which is more than 120 miles from the previous northernmost vents found during a 2005 expedition.
Other scientists have detected plumes of water from hydrothermal vents even farther north, but have been unable to find the vent fields on the seafloor to image and sample them.
In recent years, scientists have been interested in knowing how far north vigorous venting extends. That's because the ridges where such fields form are so stable up north, usually subject only to what scientists term "ultra-slow" spreading.
That's where tectonic forces are pulling the seafloor apart at a rate as little as 6/10th of an inch in a year. his compares to lower latitudes where spreading can be up to eight times that amount, and fields of hydrothermal vents are much more common.
"We hadn't expected a lot of active venting on ultra-slow spreading ridges," said Lilley.
While the active chimneys in the new field are mostly black and covered with white mats of bacteria feasting on the minerals emitted by the vents, older chimneys are mottled red as a result of iron oxidization.
All are the result of seawater seeping into the seafloor, coming near fiery magma and picking up heat and minerals until the water vents back into the ocean.
The same process created the huge mound of sulfide minerals on which the vents sit.
"That deposit is about 825 feet in diameter at its base and about 300 feet across on the top and might turn out to be the largest such deposit seen on the seafloor," said Lilley.
"Given the massive sulfide deposit, the vent field must surely have been active for many thousands of years," he added.
The area around the vents was alive with microorganisms and animals. Preliminary observations suggest that the ecosystem around these Arctic vents is diverse and appears to be unique, unlike the vent communities observed elsewhere.