Abstract

Plate tectonics would have operated very efficiently in Archean time provided the plates were, in bulk, komatiitic in composition, moving over an asthenosphere that was hotter and thus lighter and less viscous than today. Simple models of thin, dense komatiitic plates overlying a dunitic upper asthenosphere at about 1700 °C imply that resistive forces to plate motion may have been much less than today. The relatively light, low-viscosity asthenosphere would have allowed the Archean plates to move easily and would have enabled them to be subducted rapidly.

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