Fault motion and curved slickenlines: a theoretical analysis

Abstract

Slickenlines record on a fault surface the nature of relative movement of the faulted blocks. An assemblage of straight slickenlines indicates linear-translational fault motion. Curved slickenlines, on the other hand, may arise either due to rotational-translational fault motion or due to fault motions where the translation direction changes continuously (curvilinear-translational fault motion). The analysis of roto-translational fault motion involves the ratio of relative rate of rotation vs translation whereas that of curvilinear-translational fault motion involves the ratio of rate of change of translation direction to the rate of translation. The analyses reveal that an assemblage of curved slickenlines where each slickenline differs in shape from the other is indicative of roto-translational fault motion, whereas an assemblage where the slickenlines are of similar shape is the consequence of curvilinear-translational fault motion.