Geometry and kinematics of fault-bend folding.

Abstract

Many map-scale folds in sedimentary sequences are formed by the bending of fault blocks as they ride over non-planar fault surfaces. These structures, here called fault bend folds, include 'reverse-drag' or 'rollovers' associated with normal faults that flatten with depth and the bending of thrust sheets as they ride over steps in decollement. This paper presents a number of geometric and kinematic properties of parallel fault-bend folds, the most important of which is a relationship between fault shape and fold shape for sharp bends in faults. These relationships are useful tools for developing internally consistent cross sections in areas of suspected fault-bend folding, particularly in fold-and-thrust belts. -from Author