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SUMMARY:Glaciovolcanic sequences and reconstructing past Antarctic ice she
 ets  - Professor John Smellie (University of Leicester\, Dept of Geology)
DTSTART:20121126T170000Z
DTEND:20121126T180000Z
UID:TALK39406@talks.cam.ac.uk
CONTACT:Lois Salem
DESCRIPTION:Subglacially erupted volcanoes are keystone elements of many g
 laciated terrains\, past and present. Over the past decade\, rapid develop
 ments in our understanding of the glaciovolcanic sequences thus formed hav
 e enabled them to become one of the most powerful proxies in existence for
  reconstructing past ice sheets. This will be demonstrated with reference 
 to successive recent investigations in Victoria Land\, Antarctica\, where 
 multiple volcanic sequences crop out with ages extending between Late Mioc
 ene (c. 10 Ma) and late Pleistocene. The results of those studies demonstr
 ate clearly that the volcanic rocks were erupted in association with a rel
 atively thin ice sheet\, typically just a few hundred metres in thickness\
 , a conclusion substantially different from all previous studies. Moreover
 \, they have provided unequivocal information on the thermal regime of the
  ice cover and how it varied spatially and temporally. The latter finally 
 resolves a major palaeoenvironmental controversy that has raged for more t
 han 30 years over the timing of the transition to a stable Antarctic ice s
 heet and has important implications for understanding temporal variations 
 of global sea level. The studies demonstrate that the arguments that have 
 separated the two polarised scientific groups are fatally undermined and t
 herefore anachronistic. No other methodology has been capable of resolving
  this controversy and the results serve to illustrate the increasing power
  of palaeoenvironmental investigations that incorporate\, or are led by\, 
 studies of glaciovolcanic sequences. 
LOCATION:Harker Room 1\, Department of Earth Sciences
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