The kink-band triangle: a triangular plot for paleostress analysis from kink-bands

A kink-band can be graphically represented as a point on an equilateral triangle whose vertices define the angles between external foliation and kink plane, between internal foliation and kink plane, and between internal- and external-foliations. Four typical deformation paths that correspond to the four modes of kink-band growth can be discerned on this triangle. The three linear relationships between each of the kink-band angles and the inclination of the σ1-axis with respect to the unrotated layering can be transformed into a straight line on the triangular plot. Application of this plot in paleostress analysis is demonstrated by several examples. The method, however, yields best results when a large number of data on the kink-band angles are plotted and contoured on the triangular graph.