Huge fracture zone piled up Antarctic mountains

Newly discovered faulting system solves the origins of the Gamburtsew Mountains

3D model of the Gamburtsew mountains with ice cover (top) and without ice cover (middle) and view of the crust thickness under the mountains. © British Antarctic Survey
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Researchers have discovered a previously unknown, more than 2, 500-kilometer fault system under Antarctic ice. This hitherto unknown rift valley in the crust of the earth extends from the eastern Antarctic to India. This discovery solves one of the greatest mysteries of the Antarctic: the emergence of the Gamburtsev Mountains hidden under the ice. This reports the international research team in the journal "Nature".

"The Gamburtsew Mountains are the least understood tectonic phenomenon on earth, say Fausto Ferraccioli of the British Antarctic Survey and his colleagues. Geologically speaking, it is a real paradox: On the one hand, it resembles the Alps and thus a young mountain range with its towering, rugged peaks. On the other hand, it lies in the middle of one of the oldest landmasses on earth, the East Antarctic.

The newly discovered trench system now delivers the missing piece of the puzzle, which explains the emergence of the Gamburtsew Mountains, the researchers say. Because along this break shifted 250 million years ago and once again 100 million years ago the underground. These movements pushed parts of older earth's crust upwards and piled up the Gamburtsew Mountains.

Scheme of the Gamburtsew Mountains today (above) and during the formation of the mountains 250 to 100 million years ago by divergence and ascent of the Earth's crust along the East Antarctic fault. © British Antarctic Survey

Orogeny as a series of processes

Then rivers and glaciers dug deep into the mountains, leaving the rugged valleys and ravines behind. Only 34 million years ago, the ice covered the mountains and preserved it since then in its former state.

"So far, we've been used to seeing mountain building as a punctual tectonic event, not a series of processes, " says Robin Bell, co-author, Columbia University, New York City. The Gamburtsew mountains have now shown that this view is wrong. It may also be necessary to reconsider the geological history of other mountain ranges. display

View of the researchers' camp located at a height of 3.00 meters during the measurement campaign in the eastern Antarctic. British Antarctic Survey

Mapping of mountain geology using measurement aircraft

Information on the geology of the Gamburtsew Mountains and the newly discovered fracture zone was provided by data collected by several research groups in 2009 as part of the Antarctica's Gamburtsev Province (AGAP) project. The scientists had mapped the area from a research aircraft using radar measurements and measured the magnetic and gravitational field of the Earth at this point.

The data showed that the newly discovered rupture zone is similar in size and shape to the Great Rift Valley in East Africa. This rupture zone stretches from Syria in the north to Mozambique in the south, marking an area where two plates of earth are gradually falling apart.

Lakes identified under the ice

Using the new data, the researchers also identified several lakes that lie beneath the Antarctic ice in the area of ​​the East Antarctic fracture zone. These lakes are the largest of Lower Antarctic lakes and resemble the lakes along the rift valley in East Africa, die the scientists write. (Nature, 2011; doi: 10.1038 / nature10566)

(Nature / dapd, 17.11.2011 - NPO)