Page last updated at 20:10 GMT, Wednesday, 13 December 2006

Survey targets 'ghost' mountains

By Jonathan Amos
Science reporter, BBC News, San Francisco

Twin Otter aircraft (Lamont Dahoerty/M.Studinger)
Twin Otter aircraft will sweep the ice, mapping the features below

Scientists look set to undertake a detailed survey of Antarctica's Gamburtsev mountain range - one of the Earth's most enigmatic mountain groups.

It extends for more than 1,200km and rises to about 3,400m, but is totally buried under more than 600m of ice.

Computer modelling suggests these great peaks were a nucleation point some 30 million years ago for the huge ice sheets now covering the continent.

The study would be a flagship project of the 2007-8 International Polar Year.

"We want to find out what these gigantic mountains are and where they come from; because no-one really knows how they formed," Dr Michael Studinger, a principal investigator on the project, told BBC News.

"They are a big puzzle to the scientific community.

It was such a remarkable discovery that you'd have thought people would have been out there investigating straight away
Prof Charles Bentley

"They are the size of the Alps, so far as we know, and there's really no straightforward explanation as to how you get such high mountains in the interior of a continent," said the researcher from the Lamont-Doherty Earth Observatory of Columbia University, New York.

Scientists from several nations are working together on the proposal. Details have been described here at the American Geophysical Union's Fall Meeting.

Ice histories

The Gamburtsev subglacial range was discovered by a Soviet team during the last geophysical year in 1957-8, but has been the target of only limited exploration since - by an international scientific programme that took place in the 1970s.

On one level, this is hardly surprising. Anyone who goes to that part of eastern Antarctica has to battle hostile weather; temperatures can go down to more than -80C.

See a topographic map of the Antarctic bedrock

And yet, these mountains hold vitally important clues to the origin and evolution of the White Continent, and by extension the climate state experienced on Earth today.

The expedition would be a testing logistical effort as well as a physical one. A tented field camp must be set up deep in the Antarctic wilderness, and supplied with fuel to run the Twin Otter aircraft that will carry out the aerogeophysical survey.

Equipped with a suite of instruments, these planes would sweep back and forth over the ice to map the hidden terrain.

They will trace the mountains' topography, and take gravity and magnetic readings. This data should give telling clues as to the forces that built up the rocks.

One theory holds that the mountains are old "hot spot" volcanoes that punched their way through the Earth's crust, much like the Hawaiian islands have done in the middle of the Pacific.

"We will also look at internal structures in the ice, layers that record the dynamic history of the ice sheet and how it has evolved over time," explained Dr Studinger.

'Inaccessible' pole

The survey will provide crucial new inputs into climate models.

These suggest the snows that fell on the Gamburtsev peaks at the end of the Eocene Epoch were the starting point for great glaciers that eventually merged to form the East Antarctic Ice Sheet.

It was a period that saw Earth move into a cool phase as it shifted on its orbital axis and carbon dioxide levels in the atmosphere fell.

New knowledge about how ice moves in this region now will inform simulations of Antarctica's future as greenhouse gases rise and the planet warms once again.

"The Gamburtsev story is extremely relevant because in the next century we will probably exceed the levels of CO2 that in our models triggered the growth of the ice sheets," explained Dr Rob DeConto from the University of Massachusetts, Amherst.

"We don't think the ice sheet will melt away at the same level of carbon dioxide that it grew; there is delay in the system. But it is important that we get new data on the Gamburtsevs so we can refine our models."

In addition, the aerial survey is expected to support Chinese efforts "on the ground". These aim to establish a more permanent base from where a drill hole can be sent down through the covering sheet to obtain ice and rock samples.

The survey data should reveal the best places to core. It may even identify locations where future drilling projects can retrieve ancient ices for analysis - ices that are more than a million-and-a-half years old.

The project would be part of the wider AGAP (Antarctica's Gamburtsev Province) initiative, which aims to gather a range of data on a vast swathe of the continent running from the subglacial mountains to Prydz Bay on the coast.

A return to the Gamburtsev range in the coming International Polar Year would be "very appropriate", commented the veteran Antarctic explorer Professor Charles Bentley, from the University of Wisconsin-Madison.

"When the Soviets discovered the mountains, it was a complete surprise. People assumed East Antarctica was just one big Archaean platform with very few features on it - just like the interior of Canada.

"It was such a remarkable discovery that you'd have thought people would have been out there investigating straight away; but the Soviets were on a traverse to a place called the Pole of Inaccessibility and that tells you everything you need to know - it's such a difficult place to get to."

Antarctic (BBC)
The Gamburtsev range was discovered by a Soviet Antarctic expedition during the International Geophysical Year of 1957-58
The Soviets were conducting a seismic survey as they headed for the Pole of Inaccessibility, the point inland furthest from any coast
Dome A (Argus) is the highest ice elevation on Antarctica; the Vinson Massif is the highest rock feature on the continent

Jonathan.Amos-INTERNET@bbc.co.uk

SEE ALSO
Robotic route for Polar pioneers
05 Apr 06 |  Science & Environment
Antarctica's ice bottom exposed
06 Dec 05 |  Science & Environment
Huge polar initiative announced
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