Thrust-related metamorphism in Carboniferous slates of southern Patagonia (South America): The fate of forearc successions.

• Autores: Suárez, Rodrigo; González, Pablo Diego; Oriolo, Sebastián; Parada, Martín; Ghiglione, Matías; Zaffarana, Claudia Beatriz; Albano, Juan; Ponce, Juan José
• Año de publicación: 2024
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Ambientales y de la Tierra; metamorphism; petrology; Patagonia; Gondwanide; Ciencias Ambientales y de la Tierra
• Institución: Universidad Nacional de Río Negro

Fil: Suárez, Rodrigo. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: González, Pablo Diego. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Oriolo, Sebastián. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Parada, Martín. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Ghiglione, Matías. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Zaffarana, Claudia Beatriz. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Albano, Juan. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
Fil: Ponce, Juan José. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina
The Devonian to early Carboniferous western margin of Patagonia (South America) includes a NW-SE-trending magmatic arc associated with a NE-dipping palaeo-subduction zone. Along the Andean region of southern Patagonia, the Eastern Andean Metamorphic Complex developed in a forearc position and consists of a succession of very low- to low-grade metaturbidite–metabasic rocks emplaced from the Devonian to Carboniferous. There are significant uncertainties surrounding this metamorphic complex, mainly related to the tectonosedimentary setting of the basin and the subsequent conditions of deformation and metamorphism, which hinder our understanding of the orogenic architecture. To reveal the links between tectonics and metamorphism, we conducted a structural analysis and sampled metapelites to measure the illite crystallinity along a regional structural cross-section in the Eastern Andean Metamorphic Complex. Our analysis reveals broadly lower to upper anchizonal metamorphism roughly synchronous with deformation along northwards-verging thrusts. These findings support the development of a forearc hyperextended basin that was subsequently closed during the Gondwanide Orogeny (late Paleozoic), a model that reconciles previous proposals suggesting passive margin back-arc basin models. This closure led to the emplacement of supra-subduction zone ophiolites and turbidites over the continent through the landwards migration of brittle–ductile reverse shear zones.
The Devonian to early Carboniferous western margin of Patagonia (South America) includes a NW-SE-trending magmatic arc associated with a NE-dipping palaeo-subduction zone. Along the Andean region of southern Patagonia, the Eastern Andean Metamorphic Complex developed in a forearc position and consists of a succession of very low- to low-grade metaturbidite–metabasic rocks emplaced from the Devonian to Carboniferous. There are significant uncertainties surrounding this metamorphic complex, mainly related to the tectonosedimentary setting of the basin and the subsequent conditions of deformation and metamorphism, which hinder our understanding of the orogenic architecture. To reveal the links between tectonics and metamorphism, we conducted a structural analysis and sampled metapelites to measure the illite crystallinity along a regional structural cross-section in the Eastern Andean Metamorphic Complex. Our analysis reveals broadly lower to upper anchizonal metamorphism roughly synchronous with deformation along northwards-verging thrusts. These findings support the development of a forearc hyperextended basin that was subsequently closed during the Gondwanide Orogeny (late Paleozoic), a model that reconciles previous proposals suggesting passive margin back-arc basin models. This closure led to the emplacement of supra-subduction zone ophiolites and turbidites over the continent through the landwards migration of brittle–ductile reverse shear zones.