University of Cambridge > Talks.cam > Scott Polar Research Institute - Physical Sciences Seminar > Revealing the Antarctic continent with recent aerogeophysical exploration

Revealing the Antarctic continent with recent aerogeophysical exploration

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The Antarctic continent plays a pivotal role in global Earth System. The major ice sheets that cover the continent are a key influence on both global sea level rise and the climate system, and the underlying geology is a critical piece of the puzzle for studies of supercontinental evolution and processes.

I will review some recent aerogeophysical exploration projects that the British Antarctic Survey has been performing together with its national and international collaborators over the last decade to help unveil both the geological structure of the continent and to assist in studying ice sheet behaviour, through an improved knowledge of basal conditions and englacial structures. In particular I will be focussing on our latest major aerogeophysical exploration campaign over the enigmatic Gamburtsev Subglacial Mountains in interior East Antarctica that was achieved by major international collaboration during the International Polar Year.

Although coupled climate and ice sheet models have suggested that the Gamburtsevs were a key nucleation site for the early formation and evolution of the Antarctic ice sheet the origin of this high elevation mountain range in an apparently stable Precambrian shield has remained an unresolved mystery ever since their first discovery some 50 years ago. With the aid of combined radar, gravity and magnetic measurements we investigated the structure and the processes that created the Gamburtsevs. We propose that a thick crustal root was formed under the Gamburtsevs province when different parts of East Antarctica came together (collided) perhaps a billion years ago or more. Normally these old roots are lost in the mantle, but here the root was preserved, probably becauseit was very dense and dry, as is the case for example in the Urals or the TransHudson Orogen. About 250 Ma ago, and then again about 100 Ma, a major rift system that extended for over 3,000 Km from India to South Pole reactivated the old root and through a processes known as flexure helped uplift the range. However, the modern Gambuirtsevs achieved their present day rugged Alpine topography through later valley incision processes that helped uplift the peaks. The remarkable preservation of the mountain range is linked to extremely low erosion rates that are due to the overlying cover by the East Antarctic Ice Sheet, as Antarctica plunged into an icehouse world some 34 Ma.

Testing the new geophysical models for the Gamburtsevs now require and even great challenge: drilling through several thousand meters thick ice (in places)to get samples. Ambitious plans for drilling are already on the Chinese research agenda, in particular to try and find the oldest ice of our planet and perhaps recover a rock sample!

This talk is part of the Scott Polar Research Institute - Physical Sciences Seminar series.

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