Thrust-fold belt kinematics and orogenic growth in Tierra del Fuego, Argentina: implications of backthrusting for critical Coulomb wedge development.

PABLO TORRES CARBONELL; LUIS DIMIERI; EDUARDO OLIVERO

Trabajos de Geología

Universidad de Oviedo

Lugar: Oviedo, España; Año: 2009 vol. 29

0474-9588

Analysis of balanced cross-sections and of the chronostratigraphy of the deformed foreland basin successions, allows solving the structural kinematics within the eastern Fuegian thrust-fold belt. Based on the Coulomb wedge theory, we propose a chronologic and geometrically well-constrained growth history for the frontal Fuegian Andes orogen. The mountain front behaved as critical during the early Eocene, characterized by forward thrusting. The wedge became subcritical after that, until renewed forward propagation of the thrust front in the early Miocene. The large period as a subcritical wedge enhanced retrodeformation, recorded by out-of-sequence thrusting and backthrusting. We suggest that backthrusts should be considered an important mechanism to accommodate shortening in subcritical orogenic wedges.