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AGAP Antarctica findings: Gamburtsevs ghost mountains lived twice

Posted: Nov 17, 2011 04:51 pm EST

(Newsdesk) Owned by nobody, Antarctica is the core of Gondwanaland, the first land* (see comments for correction) to form on earth. The earth’s fifth continent; larger than Australia, hides the files of our world's beginning. Somewhere deep in her frozen ice, lays the world’s very first rock.

In 2009, a seven-nation team led by the British Antarctic Survey (BAS) completed a mission to uncover the Gamburtsev subglacial mountains, thought to be the birthplace of the East Antarctic Ice Sheet.

Two science teams set up two remote field camps on both sides of Dome A, the highest point on the sheet, and flew survey aircraft exploring the ice with radar, aeromagnetic and gravity sensors.

Buried mountains - and liquid water

This first glimpse of the landscape buried under up to 4km (2.5 miles) of ice was the first clear picture of the mysterious mountain range discovered by Russian scientists 50 years ago. The radar showed mountains the size of the European Alps with similar peaks and valleys and liquid water three kilometers down at the bottom of the ice sheet.

"And this adds even more mystery about how the vast East Antarctic Ice Sheet formed," said scientists back then.

"If the ice sheet grew slowly then we would expect to see the mountains eroded into a plateau shape."

"But the presence of peaks and valleys could suggest that the ice sheet formed quickly – we just don’t know. Our big challenge now is to dive into the data to get a better understanding of what happened."

Mystery solved of young-looking mountains in the middle of an old continent

Today BBC reports that the AGAP team now believes the radar data shows the Gamburtsevs actually had two lives; eroding away only to come back.

Starting before complex life had formed on the planet, the team believes continents collided, pushed up the mountains and produced an underlying thick, dense "root" that sat down in the crust.

At the time of the dinosaurs the crust started to pull apart again close to the old root, lifting the land once more to re-establish the mountains. Further uplift still was achieved as deep valleys were later cut by rivers and by glaciers that spread out and merged to form the East Antarctic Ice Sheet, entombing the Gamburtsevs in the process.

"This research really solves the mystery of how you can have young-looking mountains in the middle of an old continent," US principal investigator Dr Robin Bell from the Lamont-Doherty Earth Observatory of Columbia University told BBC.

Rock samples would confirm the model being put forward in the Nature publication.

Antarctica is divided into Greater (east) and Lesser (west) Antarctica. Great Antarctica is one stable plate, whereas the lesser Antarctica consists of several smaller, moving plates. The South Pole is on Greater Antarctica. Greater and lesser Antarctica is divided by the Transantarctic mountain range and there is a circle of mountains surrounding the coast.

While Mount Vinson (4,897m) on the southern part of the Sentinel Range is the highest altitude mark in Antarctica; Dome A is the highest ice feature, comprising a dome or eminence of 4,093 m elevation, located near the center of East Antarctica and approximately midway between the head of Lambert Glacier and the South Pole. It is thought to be one of the coldest naturally occurring places on Earth, with temperatures believed to reach -90 °C. (The lowest air temperature, -89.2°C, at the surface of the earth was recorded in July 1983 at Vostok, which is almost 600 m lower in elevation than Dome A.)

Neither flat nor very snowy, Antarctica's mountain ranges the size of the Alps in Europe are buried in her ice with only the summits exposed; making for pretty short climbs. Eternal deserts lay bare at places, dotted by meteorites and ancient skeletons preserved forever by the dry air. In the sky, the earth’s magnetic field bends, attracting meteorites and the spectacular solar winds. Katabatic winds, the strongest on earth, sweep down her plateau. The atmosphere is very thin.

Antarctica’s ice sheet, 1.5 times the size of or America or Europe, is the world’s sweet water reservoir. At places pushed up to 2000ft (600m) below sea level the ice sheet can reach more than 2.5 miles (4km) in thickness.

The ice is the result of snowfall over millions of years. All this snow, frozen and preserved, tells the history of past climates. Drilling a sample shows the chemicals and gases trapped in the ice thousands of years ago. This is helpful in understanding cyclic global warming.

#Polar #Science #feature

in 2009 the AGAP project captured the first clear picture of the mysterious Gamburtsevs mountain range near the South Pole in East Antarctica, discovered by Russian scientists 50 years ago. Radar images revealed mountains the size of the European Alps with liquid water in valleys buried deep beneath the ice. Yesterday BBC reported that the AGAP team now believes the Gamburtsevs actually had two lives; eroding away only to come back.
Image by BAS/ antarctica.ac.uk courtesy BAS/ antarctica.ac.uk, SOURCE