Tectonic rotations and transcurrent deformation south

Tectonic rotations and transcurrent deformation south of the Abancay deflection in the Andes of southern Peru Pierrick Roperch,1 Victor Carlotto,2,3 Gilles Ruffet,4 and Michel Fornari5 Received 14 April 2010; revised 2 January 2011; accepted 11... More

Tectonic rotations and transcurrent deformation south of the Abancay deflection in the Andes of southern Peru Pierrick Roperch,1 Victor Carlotto,2,3 Gilles Ruffet,4 and Michel Fornari5 Received 14 April 2010; revised 2 January 2011; accepted 11 January 2011; published 8 April 2011. [1] We report new paleomagnetic results from 55 out of 76 sites sampled at different localities along a transect from Nazca to Cuzco where the general structures of the Peruvian Andes are strongly offset across the Abancay deflection. Nine new 39 Ar/40 Ar ages better constrain the timing of volcanism along the western edge of the Western Cordillera at the latitude of Nazca. A mean paleomagnetic result from 22 sites in the lower Miocene volcanics does not show significant rotation (R = −2. 3° ± 7. 7°) of the western margin of the Central Andean Plateau since the early Miocene. Within the Western Cordillera we sampled three structural blocks bounded to the north by the Abancay fault Less