Archean andesites in the east Yilgarn craton, Australia: Products of plume-crust interaction?

The timing of onset of modern plate tectonics on Earth is one of the fundamental unsolved problems in geology: How similar were the tectonic processes on early Earth, when the mantle was hotter and the crust more ductile, to those operating today? A key line of evidence for Archean (pre–2.7 Ga) plate tectonics rests on the presence of andesites, intermediate lavas that are the signature rock type of modern subduction zones. The 2.7 Ga Eastern Goldfields superterrane of the Yilgarn craton (herein east Yilgarn craton) in Western Australia is a richly mineral-endowed crustal element that has been a prime focus of debate between proponents of an uniformitarian, plate-tectonic–driven interpretation, and advocates of an alternative model wherein the entire assemblage of igneous rocks is derived ultimately from mantle plume activity. Andesites are a key component of the volcanic stratigraphy and potentially provide critical clues to the evolution of this piece of Archean lithosphere.