Archean oceanic flake tectonics

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Abstract
Assuming that the Archean mantle was hotter and the oceanic crust thicker than at present, we estimate that the Archean oceanic lithosphere had a "sandwich" rheology, with the lower crust behaving as a soft, ductile layer. Accordingly, the Archean oceanic lithosphere had a rheological structure similar to present‐day continental lithosphere but unlike present‐day oceanic lithosphere. The thickness of the ductile layer is a decreasing function of age, while its strength is an increasing function of age. The buoyancy problem in Archean subduction could be overcome by delamination of oceanic upper crust, but mass balance calculation indicates that most Archean oceanic crust must have been recycled. Where the right dynamic conditions existed for delamination, oceanic flake tectonics may have been an important process leading to the preservation of oceanic upper crust in "greenstone belts" that are characteristic of Archean terrains.