The role of slab geometry in the exhumation of cordilleran-type orogens and their forelands: Insights from northern Patagonia

• Autores: Genge, Marie C.; Zattin, Massimiliano; Savignano, Elisa; Franchini, Marta Beatriz; Gautheron, Cécile; Ramos, Victor Alberto; Mazzoli, Stefano
• Año de publicación: 2021
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: NORTH PATAGONIA; APATITE (U-Th)/He; APATITE FISSION-TRACK; THERMO-KINEMATIC MODELING
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

In cordilleran-type orogens, subduction geometry exerts a fundamental control on the tectonic behavior of the overriding plate. An integrated low-temperature, large thermochronological data set is used in this study to investigate the burial and exhumation history of the overriding plate in northern Patagonia (40°–45°S). Thermal inverse modeling allowed us to establish that a ~2.5–4-km-thick section originally overlaid the Jurassic–Lower Cretaceous successions deposited in half-graben systems that are presently exposed in the foreland. Removal of the sedimentary cover started in the late Early Cretaceous. This was coeval with an increase of the convergence rate and a switch to a westward absolute motion of the South American Plate that was accompanied by shallowing of the subducting slab. Unroofing was probably further enhanced by Late Cretaceous to early Paleogene opening of a slab window beneath the overriding plate. Following a tectonically quiescent period, renewed exhumation occurred in the orogen during relatively fast Neogene plate convergence. However, even the highly sensitive apatite (U-Th)/He thermochronometer does not record any coeval cooling in the foreland. The comparison between Late Cretaceous and Neogene exhumation patterns provides clear evidence of the fundamental role played by inter-plate coupling associated with shallow slab configurations in controlling plate-scale deformation. Our results, besides highlighting for the first time how the whole northern Patagonia foreland was affected by an exhumation of several kilometers since the Late Cretaceous, provide unrivalled evidence of the link between deep geodynamic processes affecting the slab and the modes and timing of unroofing of different sectors of the overriding plate.
Fil: Genge, Marie C.. Università di Padova; Italia. Centre National de la Recherche Scientifique; Francia. Université de Lille; Francia. Université du Littoral; Francia
Fil: Zattin, Massimiliano. Università di Padova; Italia
Fil: Savignano, Elisa. Università di Padova; Italia
Fil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Universidad Nacional del Comahue; Argentina
Fil: Gautheron, Cécile. Université Paris Sud; Francia. Centre D'etudes de Saclay; Francia. Centre National de la Recherche Scientifique; Francia
Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina
Fil: Mazzoli, Stefano. Università degli Studi di Camerino; Italia