Geology seminar series talk: Active plate tectonics in the Paleoarchean, Simon Lamb
Plate tectonics has played a major role in the Earth’s evolution, 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 greenstone 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 Africa and Eswatini with the active New Zealand subducting plate-boundary zone. I show that there are remarkable similarities in structure and stratigraphy, with many of the distinctive features of convergent plate margins, and I argue that the simplest explanation is that plate tectonics was fully active in the Paleoarchean, generating great earthquakes on the subduction megathrust and growth folds and major low angle thrusts in the overlying accretionary prism and subsequent continental collision.