Dynamical aspects of active continental margins

Abstract

Many tectonic processes along active continental margins (and convergent plate boundaries, in general) are closely related to the dynamics of the subduction process. A major force associated with the subduction of oceanic lithosphere is the slab pull, the result of the density contrast between the cold and dense descending slab and the surrounding warmer mantle. This force is generally assumed to be compensated by resistive forces acting on the slab. In this paper I emphasize that such a compensation may be valid for a plate's convergent boundary as a whole but certainly not always for each segment of the trench system. Stress may be transmitted from the subducted slab to the attached lithospheric plate at the surface, and taking this into account provides insight into the relationship between upper mantle processes and tectonic processes near the surface (e.g. fragmentation of plates, accretion of sediments at trenches, and vertical tectonics of active continental margins).