Late-stage evolution of fault-propagation folds: principles and example

Fault-propagation folding commonly occurs near the fronts of mountain belts. This type of folding may even represent, in some thrust systems, the major mode of deformation. However, fault propagation folds are frequently altered by two kinds of late-stage evolution: breakthrough thrusting or transport on the flat. We model the geometric features of these kinds of fold, in particular the late stage modification, and present the algorithms and equations used in an original program. An application, based on an example from the Atlas mountains of Algeria, illustrates the main features of the model.