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SUMMARY:Active plate tectonics in the Paleoarchean - Simon Lamb\, Victoria
  University of Wellington
DTSTART:20241029T120000Z
DTEND:20241029T130000Z
UID:TALK220474@talks.cam.ac.uk
CONTACT:Dr Rachael Rhodes
DESCRIPTION:Plate tectonics has played a major role in the Earth’s evolu
 tion\, both in the cooling of the planetary interior\, and\, it is widely 
 argued\, the maintenance of liquid water and life at the surface. But was 
 the Earth always like this? The answer to this question is most likely to 
 lie in relicts of the early Earth’s surface\, preserved in Archean green
 stone belts and found in almost all the cratons. In this talk\, I compare 
 field relations in the 3.5 – 3.2 Ga Barberton Greenstone Belt in South A
 frica and Eswatini with the active New Zealand subducting plate-boundary z
 one. I show that there are remarkable similarities in structure and strati
 graphy\, with many of the distinctive features of convergent plate margins
 \, and I argue that the simplest explanation is that plate tectonics was f
 ully active in the Paleoarchean\, generating great earthquakes on the subd
 uction megathrust and growth folds and major low angle thrusts in the over
 lying accretionary prism and subsequent continental collision. \n\nOceania
  in the SW Pacific may provide us with the closest modern example of the s
 urface of the Paleoarchean Earth\, forming a water world with active volca
 noes\, back-arc spreading and small continental landmasses along a subduct
 ing plate boundary with local continental collision. In fact\, the eruptio
 n of boninites here in the back-arc region may be a direct analogy for the
  typical komatiitic volcanism in the early Earth. The explosive eruption o
 f Hunga Volcano near Tonga in 2022 could even provide clues to the origin 
 of life\, suggesting that life was born out of the extreme violence of pla
 te tectonics\, a far cry from Darwin’s benign and warm little pond!\n
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
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