Abstract
An oceanic plate subducting eastwards below a continental margin and resulting in crustal shortening can be inferred to have been active in central Chile during the Palaeozoic. However, the geological record for the Mesozoic and Palaeogene shows evidence of a persistent tensional régime and absence of crustal shortening. Although lateral asymmetry, inherent to a subducting model, is shown by this record, a bilateral symmetry is also well substantiated. A coupled action of plate subduction and spreading-subsidence, the latter taking place within the margin of a continental plate, is suggested to explain these features.