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

TORRES CARBONELL, PABLO; DIMIERI, LUIS; OLIVERO, EDUARDO

Departamento de Geología, Universidad de Oviedo

Simposio; International Meeting of Young Researchers in Structural Geology and Tectonics (YORSGET); 2008

Universidad de Oviedo

Analysis of balanced cross-sections and of the chronostratigraphy of the deformed sedimentary successions allows solving the structural kinematics within the eastern Fuegian thrust-fold belt. Based on the critical Coulomb wedge theory, we propose a chronologic and geometrically well-constrained growth history for the frontal Fuegian Andes orogen. The orogen behaved dominantly as subcritical from late Paleocene to middle Miocene, reaching critical taper only during a short stage in the early Miocene. These large periods as a subcritical wedge enhanced retrodeformation, recorded by out of sequence thrusting and backthrusting. We suggest that backthrusts should be considered as an important mechanism to accommodate shortening in subcritical orogenic wedges.