Mechanisms generating normal fault curvature: a review illustrated by physical models

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Abstract This paper briefly reviews the mechanisms generating fault curvature during extension, illustrates them using physical models, and discusses their applicability at different scales and for specific extensional styles. These mechanisms are in two groups. In the first, initially curved fault planes are essentially of mechanical origin. They commonly result from marked vertical changes in stress orientation and rheology within the faulted layer. Experiments suggest that such mechanisms are more likely to influence secondary faults that form where deformation and displacements are severely constrained. The second group includes faults that become curved after they form, either by volume loss due to compaction, by internal deformation of fault blocks, or by interacting sedimentation and faulting. Fault curvature due to compaction is mainly restricted to growth-faulted areas. Internal deformation of blocks affects fault shapes at the transition zone between continuous and discontinuous deformation. Block rotation during rapid deposition can lead to strongly curved fault profiles. Blocks or faults are distorted during block rotation to maintain geometric compatibility within and between the blocks. This review suggests that normal growth faults in deltaic areas are more likely to be listric than crustal-scale normal faults.