There are two competing mechanisms of deformation in plastic anisotropic materials: One is strain localization, leading to development of kink-bands, and the other is distributed deformation of kinking. As the degree of anisotropy and the bulk strength vary, there is a gradual transition from localization forming simple kink-bands, to localization forming composite kink-bands, to diffused deformation forming symmetric kinks. The relative significance of localized kink-bands and diffused kinks allows one to estimate the degree of anisotropy of the rock at the time the structures were formed.
As a strain-localization phenomenon, the onset of kink-bands is controlled by rheology, stress state and deformation conditions, but subsequent development of kink-bands is largely kinematic. Kink-band boundaries migrate through material and rotate toward higher angles to the shortening direction as deformation advances. However, kink-band boundary migration is limited and does not lead to formation of kinks except in areas where a pair of conjugate kink-bands intersect.
Kinks are produced by folding of the anisotropy with axial planes close to 90 with respect to the shortening direction. Like kink-band boundaries, such axial planes may migrate through material as deformation advances.