Quaternary tectonics and seismic potential of the Andean retrowedge at 33–34°S

Abstract

AbstractThe Andean retrowedge, located between 33°S and 34°S, lies in the transition region of the Pampean flat-slab subduction zone to the north and a normal subduction zone to the south. Neotectonic structures and shallow seismicity are very common north of this segment and become progressively less frequent southwards. The Frontal Cordillera and the Cerrilladas Pedemontanas are the main morphostructures involved in the Quaternary deformation of this region. The Frontal Cordillera is a thick-skinned fold-and-thrust belt uplifted since Late Miocene time. The Cerrilladas Pedemontanas are low-relief hills that represent the mild inversion of the Cuyo Triassic rift depocentre since Pliocene time. Middle Miocene–Holocene synorogenic strata cover the Cuyo basin and surrounding foreland areas. The Quaternary tectonic evolution of this area has been established through integration of new data from fieldwork in the Frontal Cordillera piedmont with subsurface information and previously published data. Mean Late Pleistocene uplift rates ranging between 0.21 and 0.92 mm a−1 and earthquake minimum moment magnitudes (Mw) of c. 6.4–6.7 have been estimated for the morphostructural units analysed in this manuscript.