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Getting to the root of the Gamburtsev Mountains: enigma hidden beneath the Antarctic Ice Sheet

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During the International Polar Year 2008-09 seven nations, including the UK, pooled their logistic and scientific resources to explore the largest unexplored continental frontier on Earth, the interior of East Antarctica, within the AGAP project. Here I present the results of this challenging and ambitious international project that led to major discoveries regarding the structure and origin of the enigmatic Gamburtsev Subglacial Mountains hidden beneath Dome A, the least understood mountain range on Earth (Ferraccioli et al., 2011, Nature; Bell, Ferraccioli et al., 2011 Science). I will show the major challenges that had to be overcome to explore this frontier region. I will explain why investigating the origin and evolution of the enigmatic Gamburtsev Mountains hidden beneath an ice sheet that is in places more than 4 km thick and in others is less than a few hundred meters thick is important to: i) comprehend the geological evolution of the interior of East Antarctica with the global supercontinental puzzle and ii) understand the role of intraplate mountain building in the nucleation and long term stability of the Antarctic ice sheet, following the Eocene-Oligocene climate transition. Stunning new aerogeophysical images coupled with continental-scale views from satellite data enabled us to reveal that East Antarctica is dissected by one of the longest continental rift systems on Earth that resembles in terms of extent the East Antarctic Rift System. The rift exploited the pre-existing tectonic boundaries separating a mosaic of previously unknown basement provinces that can now be recognised as forming the interior of East Antarctica. We proposed that rifting and faulting within the East Antarctic plate triggered the initial uplift of the Gamburtsev Mountains, probably both in Permian and Cretaceous times, while the remarkably rugged Alpine morphology of its peaks is due to isostatic responses to both fluvial and glacial valley incision that likely occurred throughout the Cenozoic. Alternative or additional views involving intraplate compression may be possible but remain to be more fully tested. Our new geophysical interpretations challenge the traditional paradigm of a geologically stable East Antarctic continent since Cambrian times. It is now apparent that the interior of East Antarctica was not immune at all from the large-scale tectonic processes responsible for the Mesozoic break-up of the Gondwana supercontinent. More broadly speaking it is clear that continental interior tectonics must be considered in large-scale geological and geophysical research efforts (in Antarctica and beyond), and its impacts on landscape, climate and ice sheet evolution need to be more fully understood.

This talk is part of the Sedgwick Club talks series.

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