Thermomechanical models of mantle convection and melting in an inferred hotter Archean Earth show the emergence of pressure-temperature (P-T) regimes that resemble present-day plate tectonic environments yet developed within a non–plate tectonics regime. The models’ P-T gradients are compatible with those inferred from evolving tonalite-trondhjemite-granodiorite series rocks and the paired metamorphic belt record, supporting the feasibility of divergent and convergent tectonics within a mobilized, yet laterally continuous, lithospheric lid. “Hot” P-T gradients of 10–20 °C km–1 form along asymmetric lithospheric drips, then migrate to areas of deep lithospheric downwelling within ~300–500 m.y., where they are overprinted by high-pressure warm and, later, cold geothermal signatures, up to ~8 °C km–1. Comparisons with the crustal production and reworking record suggest that this regime emerged in the Hadean.
Research Article|August 20, 2019
Reconciling thermal regimes and tectonics of the early Earth
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F.A. Capitanio, O. Nebel, P.A. Cawood, R.F. Weinberg, P. Chowdhury; Reconciling thermal regimes and tectonics of the early Earth. Geology doi: https://doi.org/10.1130/G46239.1
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