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SUMMARY:The uplift and erosion history of the Gamburtsev Subglacial Mounta
 ins and their role in the formation of the East Antarctic Ice Sheet - Guy 
 Paxman (Durham)
DTSTART:20260506T130000Z
DTEND:20260506T140000Z
UID:TALK246415@talks.cam.ac.uk
CONTACT:Alice Turner
DESCRIPTION:Valley networks in mountain ranges record the interactions bet
 ween climate\, tectonics\, and geology. While drainage network analysis ha
 s transformed our understanding of these interactions in subaerial setting
 s\, the landscape evolution of ice-covered orogens is poorly known. The Ga
 mburtsev Subglacial Mountains are a ~600 km-long mountain range situated b
 eneath the East Antarctic Ice Sheet\, the largest ice sheet on Earth. Thes
 e mountains are thought to have been an important nucleation site for the 
 ice sheet approximately 34 million years ago and are now buried beneath ~2
  km of ice. Airborne geophysical surveying has revealed that the Gamburtse
 vs are characterised by a rugged\, incised landscape\, but their geologica
 l structure and uplift history remain enigmatic.\n\nThis talk will explore
  how radio-echo sounding (radar) data can be used to extract valley networ
 ks and longitudinal profiles from the Gamburtsevs. We combine analysis of 
 these valley profiles with gravity and magnetic anomalies to infer details
  of the tectonic and geomorphic development of the mountains. For example\
 , channel steepness indices and their relationship with magnetic anomalies
  allow us to confirm the positions of major geological boundaries that may
  date back to Gondwana assembly. Drainage basin analysis and stream power 
 incision modelling are used to show that the morphology of the valley netw
 orks is largely consistent with fluvial incision that occurred prior to Eo
 cene/Oligocene glaciation. This relic landscape is now preserved beneath t
 he non-erosive centre of the East Antarctic Ice Sheet. Tectonic geomorphic
  analysis suggests that the routing of Gamburtsev fluvial systems was like
 ly influenced by extensional faulting within East Antarctica\, which may h
 ave controlled pre-glacial base level and the locations of interior sedime
 nt depocentres. We use these findings\, together with independent estimate
 s of denudation rates\, to evaluate competing scenarios for the mechanism(
 s) and timing of Gamburtsev mountain uplift and valley incision. Finally\,
  through numerical ice-sheet modelling\, we examine how the uplift of thes
 e mountains may have played a crucial role in governing the nature and tim
 ing of the initial growth of the East Antarctic Ice Sheet.
LOCATION:Wolfson Lecture Theatre
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