Latitudinal variations in the amount of tectonic shortening and deformation style may have been controlled by regional heterogeneities in the upper continental crust and subducted slab (Jordan et al., 1983;Mpodozis & Ramos, 1989). Among these, the Pampean flat-slab subduction zone (27°S-33°S) is one of the most remarkable features in this orogen (Cahill & Isacks, 1992;Gutscher et al., 2000). It is characterized by a series of tectonic domains, with an accretionary wedge in the Coastal Cordillera, Quaternary deposits in the Central Valley, a hybrid thrust belt in the Principal Cordillera, a rigid block uplift in the Frontal Cordillera, basement uplift in the Precordillera and the Sierras Pampeanas, and a series of Neogene-Quaternary broken foreland basins (