Archaean global dynamics

Abstract

Archaean global tectonics and continental growth is founded on the existence of a differentiated upper mantle of average lherzolite composition. A thick segregated basalt layer constitutes the upper part of the upper mantle. The geodynamic state is determined by a high deeper mantle temperature and a mobile cool shallow basalt layer and this can explain the growth of the Archaean craton and its geothermal state. Of particular importance for continental tectonics are isostatic conditions which differ from the present in allowing for large relative and absolute vertical displacements.