Evolution of passive continental margins and initiation of subduction zones

Abstract

The initiation of subduction is a key element in plate tectonic schemes for the evolution of the Earth's lithosphere. Nevertheless, up to present, the underlying mechanism has not been very well understood (e.g. Dickinson and Seely, 1979; Hager, 1980; Kanamori, 1980). The insight into the initiation of subduction process has lagged far behind the progress made in the last few years in the study of other aspects of plate tectonics, making this topic an outstanding problem'in geodynamics (Dziewonski and Boschi, 1980; Flinn, 1982). Vlaar and Wortel (Vlaar, 1975; Vlaar and Wortel, 1976; Wortel, 1980) have shown that a fundamental parameter in lithospheric studies is provided by the age of the oceanic lithosphere. It was, therefore, decided to investigate whether the age-dependence of lithospheric properties might provide a clue to better understanding of the initiation of the subduction process (Cloetingh et al., 198l). It is the aim of this thesis to give a systematic investigation into the mechanical conditions under which the initiation of a subduction zone can take place.