Deformación compresiva cuaternaria en la Cordillera Principal de Chile central (Cajón del Maipo, este de Santiago)

a detailed study of recent sediments in the maipo river valley (cajón del maipo), east of santiago, shows a compressive deformation documented by coeval reverse faults and drag-folds. these structures are characteristic of a principal stress direction trending roughly n-s (n338°e) that also affects the older sediments of the abanico formation constituting the bedrock of the quaternary alluvial terraces. two deformation episodes are superposed in the bedrock: a neogene deformation event (post 9 ma), having an e-w-trending al, and a late quaternary event with al roughly trending n-s. the latter would be the result of regional-scale partitioning of the oblique convergence vector between the nazca and south american plates; a buttress at 33°s would produce a north-south velocity gradient in the forearc leading to regional, north-south shortening. shallow crustal seismicity in the inner forearc (main cordillera) is -at least in part- compatible with the compression direction as obtained from the kinematic analysis of mesoscopic fault-slip data.