Structural evolution of a composite middle to lower crustal section: The Sierra de Pie de Palo, northwest Argentina

• Autores: Mulcahy, S. R.; Roeske, S. M.; McClelland, W. C.; Jourdan, F.; Iriondo, A.; Renne, P. R.; Vervoort, J. D.; Vujovich, Graciela Irene
• Año de publicación: 2011
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: STRUCTURE; GEOCHRONOLOGY; PIE DE PALO; CUYANIA / PRECORDILLERA TERRANE
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The Sierra de Pie de Palo of northwest Argentina preserves middle to lower crustal metamorphic rocks that were penetratively deformed during Ordovician accretion of the Precordillera terrane to the Gondwana margin. New structural, petrologic, and geochronologic data from a 40 km structural transect reveals that the Sierra de Pie de Palo preserves a middle to lower crustal ductile thrust complex consisting of individual structural units and not an intact ophiolite and cover sequence. Top-to-the-west thrusting occurred intermittently on discrete ductile shear zones from ∼515 to ∼417 Ma and generally propagated toward the foreland with progressive deformation. Ordovician crustal shortening and peak metamorphic temperatures in the central portion of the Sierra de Pie de Palo were synchronous with retro-arc shortening and magmatic flare-up within the Famatina arc. Accretion of the Precordillera terrane resulted in the end of arc flare-up and the onset of synconvergent extension by ∼439 Ma. Continued synextensional to postextensional convergence was accommodated along progressively lower grade shear zones following terrane accretion and the establishment of a new plate margin west of the Precordillera terrane. The results support models of Cordilleran orogens that link voluminous arc magmatism to periods of regional shortening. The deformation, metamorphic, and magmatic history within the Sierra de Pie de Palo is consistent with models placing the region adjacent to the Famatina margin in the middle Cambrian and not as basement to the Precordillera terrane.
Fil: Mulcahy, S. R.. University of Nevada; Estados Unidos. University of California at Davis; Estados Unidos
Fil: Roeske, S. M.. University of California at Davis; Estados Unidos
Fil: McClelland, W. C.. University of Iowa; Estados Unidos
Fil: Jourdan, F.. Curtin University; Australia. Berkeley Geochronology Center; Estados Unidos
Fil: Iriondo, A.. Universidad Nacional Autónoma de México; México
Fil: Renne, P. R.. Berkeley Geochronology Center; Estados Unidos. University of California at Berkeley; Estados Unidos
Fil: Vervoort, J. D.. Washington State University; Estados Unidos
Fil: Vujovich, Graciela Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina