This is an extraordinary piece of
geological detective work that is important.
It is noteworthy that this rift compares to the African rift. There are a number of extinct rift about but
this one appears to be a live one and it is interesting. It is possibly the only way in which the Antarctic
cap could one day be eliminated but that still will take tens of millions of
years at least. I think the present
global disposition is vastly more stable than anyone assumes.
One of the triumphs of modern
science has been the relentless mapping on the globe’s geology. It is a long way from been complete, but
bricks are now been continuously added and it represents the ongoing work of
tens of thousands of individuals out there.
There are many more questions out
there.
Gamburtsev Mountains enigma unraveled in East Antarctica
by Staff Writers
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.
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 3km of ice - during the International Polar Year (2007- 09) 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 3,000km 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 km" 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.
No comments:
Post a Comment