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The
birth of the Gamburtsev Subglacial Mountains buried beneath the vast
East Antarctic Ice Sheet—a puzzle mystifying scientists since their
first discovery in 1958—is finally solved. The remarkably long
geological history explains the formation of the mountain range in the
least explored frontier on Earth and where the Antarctic Ice Sheet first
formed. The findings are published this week in the journal Nature.
A
seven-nation team of scientists explored the Gamburtsev Subglacial
Mountains – buried beneath up to 3 km of ice—during the International
Polar Year (2007-2009) by using two twin-engine aircraft equipped with
ice penetrating radars, gravity meters and magnetometers.
By
analyzing the new data, the researchers describe the extraordinary
processes—which took place over the last billion years—that created
and preserved a root beneath the mountains and the East Antarctic rift
system—a 3,000 km long fracture in the earth’s surface that extends from
East Antarctica across the ocean to India.
One
billion years ago, before animals and plants evolved on Earth, several
continents (or micro-continents) collided, crushing the oldest rocks of
the mountain range together. This event formed a thick crustal root
extending deep beneath the mountain range. Over time these ancient
mountains were eroded but the cold dense root was left behind.
Around
250-100 million years ago—when dinosaurs walked the Earth—rifting paved
the way for the supercontinent Gondwana to break apart, which included
Antarctica, causing the old crustal root to warm. This rejuvenated
crustal root, together with the East Antarctic Rift forced the land
upwards again reforming the mountains. Rivers and glaciers carved deep
valleys and this helped uplift the peaks to create the spectacular
landscape of the Gamburtsevs, which resemble the European Alps. The East
Antarctic Ice Sheet, which formed 34 million years ago and covers 10
million km² of our planet (an area the size of Canada), protected the
mountains from erosion.
Lead
author, Dr. Fausto Ferraccioli from British Antarctic Survey says,
“Understanding the origin of the Gamburtsevs was a primary goal of our
International Polar Year expedition. It was fascinating to find that the
East Antarctic rift system resembles one of the geological wonders of
the world—the East African rift system—and that it provides the missing
piece of the puzzle that helps explain the Gamburtsev Subglacial
Mountains. The rift system was also found to contain the largest
subglacial lakes in Antarctica.”
Co-author,
Dr. Carol Finn from US Geological Survey says, “Resolving the
contradiction of the Gamburtsev high elevation and youthful Alpine
topography but location on the East Antarctic craton by piecing together
the billion year history of the region was exciting and challenging. We
are accustomed to thinking that mountain building relates to a single
tectonic event, rather than sequences of events. The lesson we learned
about multiple events forming the Gamburtsevs may inform studies of the
history of other mountain belts.”
Co-author,
Dr. Robin Bell of Columbia University’s Lamont-Doherty Earth
Observatory says, “The next steps will be to assemble a team to drill
through the ice into the mountains to obtain the first rock samples from
the Gamburtsevs. Amazingly, we have samples of the moon but none of the
Gamburtsevs. With these rock samples we will be able to constrain when
this ancient piece of crust was rejuvenated and grew to a magnificent
mountain range.”
“It
is very fitting that the initial results of Antarctica’s Gamburtsev
Province (AGAP) project are coming out 100 years after the great
explorers raced to the South Pole,” said Alexandra Isern, Programme
Director at the National Science Foundation. “The scientific explorers
of the AGAP project worked in harsh conditions to collect the data and
detailed images of this major mountain range under the East Antarctic
Ice Sheet. The results of their work will guide research in this region
for many years to come.”
These
discoveries in central East Antarctica have significant implications
for understanding mountain building and ice sheet evolution within
continental interiors.
Antarctica’s Gamburtsev Province Project at Columbia University
Antarctica’s Gamburtsev Province Project at British Antarctic Survey
