THE ROLE OF GRAVITATIONAL POTENTIAL-ENERGY IN ACTIVE DEFORMATION IN THE SOUTHWESTERN UNITED-STATES

In orogenic belts, intrinsic (buoyancy) and extrinsic (boundary) force s act on the continental lithosphere; determining the relative importa nce of these forces is fundamental to understanding the dynamics of co ntinental deformation. In the western United States, estimates of grav itational potential energy show that, given available constraints on r heology, buoyancy forces are sufficient to produce the wide variety of rates and styles of observed deformation, including absence of deform ation. This underscores the importance of gravitational potential ener gy for deformation in orogenic belts.