Patterns of imbricate thrusting

Through the use of seismic reflection profiles, satellite images, and balan ced kinematic models, we describe patterns that help to identify imbricate structures and define the sequence of thrusting in fold-and-thrust belts, m easures of folding shear strains are employed to define break-forward syste ms in which younger, deeper faults refold overlying thrust sheets. In contr ast, break-backward sequences form a wide range of viable geometries that a re not expected to conserve these folding strains. Thus, measures of foldin g shear strains provide a means to define thrusting sequence. We also explo re map-view patterns of imbricate thrusting by using three-dimensional mode ls and stereoscopic satellite images, We present an example from the Peruvi an Andes in which these map patterns are combined with seismic reflection p rofiles to define a complex imbricate system with components of both break- forward and break-backward thrusting. These integrated methods provide new tools for understanding the deformational histories of fold-and-thrust belt s, including the definition of complex structural closures with opportuniti es for hydrocarbon-reservoir duplication.