Active crustal-scale pure shear foreland deformation of Western Argentina Abstract


  • Reanalysis of teleseismic body waves from the June 11, 1944 San Juan, Argentina earthquake, plus other moderate earthquakes in the region, demonstrate that pure-shear deformation with steep conjugate planar faults extending to 40-50 km characterizes active deformation of the Andean foreland. This deep-seated deformation via blind reverse faulting is masked by thin-skinned structures in the shallow crust. Existing crustal-scale models invoke thin-skinned fault geometries, which are splays from an east-dipping mid-crustal d├ęcollement. These new results illustrate primary role of thick-skinned pure-shear reverse faulting, which involves more than 75% of the crust, and must be balanced by lower crustal and mantle flow.


publication date

  • 2009