Crustal-scale pure shear foreland deformation of western Argentina

Abstract

New analyses of teleseismic body waves from moderate earthquakes in western Argentina demonstrate that active shortening of the Andean foreland occurs on reverse faults extending to 40-50 km depth. Existing crustal-scale models of foreland deformation invoke thin-skinned fault geometries, which root into an east-dipping mid-crustal décollement. Whereas thin-skinned thrust sheets dominate shallow-crustal structure, seismological and geological data illustrate that planar reverse faults and pure-shear deformation involving more than 75% of the crust characterizes this thick-skinned structural province. Copyright © 2010 by the American Geophysical Union.