Geometry and origin of fault-related folds in extensional settings

The majority of folds in extensional tectonic settings are associated with normal fault systems over a wide range of scales. Longitudinal folds include drag folds, reverse-drag folds and rollover folds. Drag folds have a smaller wavelength than reverse-drag or rollover folds and may be superimposed on these larger structures. Basin-scale synclines are the largest type of transverse folds. Transverse folds are also associated with segmented fault systems: hanging-wall synclines are located near the centers of fault segments, whereas hanging-wall anticlines are found at segment boundaries where the fault segments commonly overlap. Some transverse folds may be caused by movement along an undulatory fault surface. -from Author