Comment on “The West Andean Thrust, the San Ramón Fault, and the seismic hazard for Santiago, Chile” by Rolando Armijo et al.

Abstract

[1] In a recent contribution, Armijo et al. [2010] provided a provocative model to interpret the kinematics and style of deformation of the central Andes at ∼33°S latitude (SL) in which they suggested that the Andes grew trenchward instead of cratonward. They challenge not only the hypothesis on building of the Andean belt but also the critical taper wedge model [Davis et al. 1983] and histories of thrust tectonics of different subduction systems like the South and North American Cordilleras. Armijo et al. [2010] assume that the “main” orogenic loading (represented by the cordilleran shortening) shifted westward generating a “foreland basin”: the Chilean Central Depression, bounded to the west by the Coastal Cordillera. [2] Our discussion is focused on the development of Andean basins and associated synorogenic sedimentary stratigraphy. We present three main lines of reasoning that, in turn, are interrelated: (1) thrust shifting, (2) basin formation along the Argentine foreland (considered explicitly by Armijo et al. [2010] as back‐thrust‐related basins), and (3) the Chilean Central Depression: a foreland basin?