The geodynamics of lithospheric extension

Lithospheric extension is a fundamental plate tectonic process controlling the collapse of mountain belts, the break-up of continents and the formation of new oceanic basins. This review summarises major advances on understanding: a) the nature of the ocean–continent transition, b) the origin and evolution of detachment faults, c) the dynamic strength of continental lithosphere during extension, and d) the role of magmatism during extension. Major steps have been made in mapping out the complexities of the ocean–continent transition zone, particularly in magma-poor rifted margins, where extensional structures are not masked by voluminous magmatism. The role of detachment faulting during rifting seems to be crucial and explains observations on depth-dependent stretching of the lithosphere. Despite new insights into the dynamic behaviour of the lithosphere, its rheological response remains a major uncertainty in modelling the evolution of extensional systems. Likewise, the multiple roles that basaltic magmatism may have in modifying extension remain a key question. Future insights into the global behaviour of extensional systems will be gained by constraining lithospheric rheology through integrating structural evolution and magmatism in the field, geodetic measurements of active extension, thermochronology, seismic surveys and drilling programs.