Multiple migmatite events and cooling from granulite facies metamorphism within the Famatina arc margin of northwest Argentina

• Autores: Mulcahy, Sean R.; Roeske, Sarah M.; McClelland, William C.; Ellis, Joshua R.; Jourdan, Fred; Renne, Paul R.; Vervoort, Jeffrey D.; Vujovich, Graciela Irene
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: OCLOYIC DEFORMATION; CHANIC DEFORMATION; CUYANIA; CHILENIA
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The Famatina margin records an orogenic cycle of convergence, metamorphism, magmatism, and extension related to the accretion of the allochthonous Precordillera terrane. New structural, petrologic, and geochronologic data from the Loma de Las Chacras region demonstrate two distinct episodes of lower crustal migmatization. The first event preserves a counterclockwise pressure-temperature path in kyanite-K-feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at ∼12 kbar and 868°C at 461 ±1.7 Ma. The shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive Ordovician migmatization throughout the Famatina margin. One-dimensional thermal modeling coupled with regional isotopic data suggests Ordovician melts remained at temperatures above their solidus for 20–30 Ma following peak granulite facies metamorphism, throughout a time period marked by regional oblique convergence. The onset of synconvergent extension occurred only after regional migmatites cooled beneath their solidus and was synchronous with the cessation of Precordillera terrane accretion at ∼436 Ma. The second migmatite event was regionally localized and occurred at ∼700°C and 12 kbar between 411 and 407 Ma via vapor saturated melting of muscovite. Migmatization was synchronous with extension, exhumation, and strike-slip deformation that likely resulted from a change in the plate boundary configuration related to the convergence and collision of the Chilenia terrane.
Fil: Mulcahy, Sean R.. University of California at Berkeley; Estados Unidos
Fil: Roeske, Sarah M.. University of California at Davis; Estados Unidos
Fil: McClelland, William C.. University of Iowa; Estados Unidos
Fil: Ellis, Joshua R.. Kinross Gold Corporation; Canadá
Fil: Jourdan, Fred. Curtin University; Australia
Fil: Renne, Paul R.. University of California at Berkeley; Estados Unidos
Fil: Vervoort, Jeffrey 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