Abstract
Analysis of balanced cross-sections and of the chronostratigraphy of the deformed forelandbasin successions allows to solve the structural kinematics of the eastern Fuegian thrust-fold belt. Basedon the Coulomb wedge theory, we propose a chronologically and geometrically well-constrainedgrowth history for the frontal Fuegian Andes orogen. The mountain front behaved in a critical mannerduring the Early Eocene, characterized by forward thrusting. The wedge became subcritical afterthat, until renewed forward propagation of the thrust front in the Early Miocene. The long period asa subcritical wedge enhanced retrodeformation, recorded by out-of-sequence thrusting and backthrusting.We suggest that backthrusts should be considered an important mechanism for accommodatingshortening in subcritical orogenic wedges.
