How many arcs can dance on the head of a plume?: A ‘Comment’ on: A critical assessment of Neoarchean ‘plume only’ geodynamics: Evidence from the Superior province, by Derek Wyman, Precambrian Research, 2012

Bédard (2006) proposed that Archaean cratons formed above large, long-lived mantle plumes, where the thick basaltic crust cannibalized itself to generate TTGs (tonalite-trondhjemite-granodiorite) and complementary eclogitic restites. In this model the dense eclogitic restites foundered into the depleted upper mantle and refertilized it, triggering generation of new basaltic melt pulses, and so eclogite represents a catalyst for coupled crust–mantle differentiation. Since most of the eclogite is destroyed in the upper mantle, voluminous hidden eclogitic reservoirs are not predicted. The model was not intended to explain the generation of overprinting fabrics and terrane assembly, but to account for chemical evolution of the coupled crust–mantle system in the initial stages of craton development. Wyman (2013) argues that the models and hypotheses presented in Bédard (2006) are unrealistic and irrelevant, and reaffirms his opinion that the Archaean world was dominated by plate tectonics. The criticisms and arguments of Wyman (2013) are invalid.

► Archaean terranes do not resemble modern convergent margin assemblages.
► Plate tectonic models cannot be applied to the Archaean.
► Archaean cratons could have formed by coupled catalytic differentiation of the crust and mantle.