The geodynamic mechanism of Archaean cratons is still a controversial topic in modern geology (Arndt, 2013; Condie, 2015; Bédard, 2018). At the centre of the controversy is whether or not Phanerozoic-style plate tectonics can be applied to the Archaean. If not, what is the main tectonic mechanism governing crustal formation and growth during Archaean time? A number of lines of evidence seem to support Archean plate tectonics, including TTG (Tonalite-Trondhjemite-Granodiorite) rocks dominant in Archean terrains similar to those in modern subduction zones; some Archean rocks geochemically with arc-affinities, and partial melting of mafic rocks to form TTG requiring H2O, which favours subduction zones (Arndt, 2013), etc. However, plate tectonics cannot well explain the following lithological, structural and metamorphic features that characterize Archean cratons: (1) dominant bimodal volcanic assemblages in the Archean greenstones (; (2) Archean komatiites whose formation needed a melting process that occurred at 1600-1900°C; (3) nearly coeval emplacement of TTG plutons over a whole craton within a narrow time gap; (4) mass balance problems if Archean TTG rocks were derived from the 10-30% partial melting of either eclogites or garnet amphibolites; (5) dominant domiform structures with vertical lineations; and (6) metamorphism characterized by anticlockwise P–T paths involving isobaric cooling following the peak metamorphism, which reflects the origin of the metamorphism related to underplating and intrusion of mantle-derived magmas. Although a continental magmatic arc model can also explain metamorphism involving anticlockwise P–T paths, it requires similar-aged relatively high pressure terrains with clockwise P-T paths to form paired metamorphic belts like those in current magmatic arcs (Brown, 2006), but such relatively high pressure rocks are absent in most Archean cratons. Considering the above lines of evidence against the Archean plate tectonics, we think that the formation and evolution of Archean continents (cratons) must have been governed by some non-plate tectonics, such as mantle plumes, heat pipes, sagduction, stagnant lids, etc, although none of these non-plate tectonic models can successfully explain all features of Archean cratons.

Reference(s)

Arndt, NT, 2013, Formation and Evolution of the Continental Crust. Geochemical Perspectives, v. 2(3), p. 405-533.
 
Bédard, JH, 2018, Stagnant lids and mantle overturns: Implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geoscience Frontiers, v. 9, p. 19-49.
 
Brown, B, 2006. Duality of thermal regimes is the distinctive characteristic of plate tectonics since the Neoarchean.Geology, v.34, p. 961-964.
 
Condie, KC, 2015, Changing tectonic settings through time: indiscriminate use of geochemical discriminant diagrams. Precambrian Research, v. 266, p. 587-591.