Sascha Brune, Folarin Kolawole , Jean-Arthur Olive, Sarah Stamps, W. Roger Buck, Susanne Buiter

A rift is a nascent plate boundary where the continental lithosphere is extended and possibly broken. In this review, we focus on fundamental rift processes and how they evolve through time. We aim at providing a modular overview of the driving forces, resisting factors, and weakening processes as well as how their interaction generates the large variety of rifts on Earth. Rifting initiates when the joint contribution of lithospheric buoyancy forces, mantle tractions, and subduction-related forces overcome the lithospheric strength. Subsequently, rifting is facilitated by softening mechanisms, such as frictional weakening, diking and surface processes, but also by inherited rheological weaknesses, such as those coinciding with currently active rifts in East Africa. These positive feedback effects may however be counter-balanced by dynamic processes resisting deformation such as isostatic forces or lithospheric cooling, which may ultimately lead to the abandonment of a rift. A fundamental understanding of the force balance in rifts is required to assess their controls on rift-wide stress fields, which is essential when georesources like geothermal energy are to be exploited in a responsible way. These cross-scale interactions can only be understood through multidisciplinary approaches that integrate geophysical and geochemical data with modern modelling techniques.