Marc Flemming
Renovator
offline
Registered: Jan 2003
Local time: 04:58 PM
Location: Santa Cruz
Posts: 3663
|
Scientists are returning to one of the most remarkable places on our planet, the so-called Lost City of Atlantis.
An expedition from the University of Washington is to use the submersible Alvin to take the first samples from the formation of 18-storey-high hydrothermal vents in the mid-Atlantic.
Formed by superheated water seeping out of the seafloor, the strange structures are made in a different way from other known hydrothermal vents.
It could be home to new forms of life and it could shed new light on the origin of life on the Earth and on other worlds as well.
'Black smokers'
The so-called Lost City of Atlantis was discovered by accident in December 2000.
An automated sea-bed explorer stumbled across it near the end of a University of Washington, Scripps Institution of Oceanography and US National Science Foundation expedition to survey the mid-Atlantic.
Sketchy details were sent back allowing the submersible Alvin to briefly visit the site before bad weather ended the expedition.
Soon it was dubbed the Lost City of Atlantis, and it became clear that it was like no other hydrothermal vent system yet discovered.
Until then, known hydrothermal vent systems were formed when inky superheated water, saturated with chemicals, seeped from undersea volcanic vents. Towers of deposits formed around the vents that were called "black smokers."
These systems were home to unique ecosystems that lived off sulphur-eating bacteria.
The Lost City appears to be very different from this. It is a far older than other vents, with taller towers - up to 55 m (180 ft) - made of a different material from the dark mottled mix of sulphides in the black smokers.
The system is being heated by old hot mantle rocks, a million years-old, not young volcanism.
Origin of life
The towers are composed of carbonate, the same material as limestone in caves. It appears that they are formed by water that is somewhat cooler than the 400C that forms the black smokers, possibly 40 - 70C.
Since it was discovered, it has been visited by a film crew and Russian scientists, but the forthcoming expedition will be the first time the formation will have been studied in detail.
The researchers will once again use the Alvin submersible for a series of six-hour dives to survey the region and collect samples.
Some believe that the Lost City spires could actually be the most common form of hydrothermal vent on the seafloor, with many others awaiting discovery along the 10,000 km (6,200 mile) Mid-Atlantic Ridge.
The site may have importance for astrobiology as well.
Researchers think that life may have started on our planet in a place just like it, and the same could be happening on other worlds such as under the ice-crusted ocean of Jupiter's moon Europa.
During the expedition the scientists will be posting a daily report on the internet.
Source: BBC
|
04-23-2003 01:08 AM
