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Título:
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Unraveling the origins and P-T-t evolution of the allochthonous Sobrado unit (Órdenes Complex, NW Spain) using combined U–Pb titanite, monazite and zircon geochronology and rare-earth element (REE) geochemistry
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Autores:
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Benítez Pérez, José Manuel ;
Castiñeiras García, Pedro ;
Gómez Barreiro, Juan ;
Martínez Catalán, José Ramón ;
Kylander-Clark, Andrew ;
Holdsworth, Robert
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Tipo de documento:
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texto impreso
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Editorial:
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European Geosciences Union, 2020
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Dimensiones:
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application/pdf
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Nota general:
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cc_by
info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Geología: Geodinámica
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Materia = Ciencias: Geología: Geoquímica
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Materia = Ciencias: Geología: Petrología
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Tipo = Artículo
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Resumen:
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The Sobrado unit, within the upper part of the Órdenes Complex (NW Spain) represents an allochthonous tectonic slice of exhumed high-grade metamorphic rocks formed during a complex sequence of orogenic processes in the middle to lower crust. In order to constrain those processes, U–Pb geochronology and rare-earth element (REE) analyses of accessory minerals in migmatitic paragneiss (monazite, zircon) and mylonitic amphibolites (titanite) were conducted using laser ablation split stream inductively coupled plasma mass spectrometry (LASS-ICP-MS). The youngest metamorphic zircon age obtained coincides with a Middle Devonian concordia monazite age (?380?Ma) and is interpreted to represent the minimum age of the Sobrado high-P granulite facies metamorphism that occurred during the early stages of the Variscan orogeny. Metamorphic titanite from the mylonitic amphibolites yield a Late Devonian age (?365?Ma) and track the progressive exhumation of the Sobrado unit. In zircon, cathodoluminescence images and REE analyses allow two aliquots with different origins in the paragneiss to be distinguished. An Early Ordovician age (?490?Ma) was obtained for metamorphic zircons, although with a large dispersion, related to the evolution of the rock. This age is considered to mark the onset of granulite facies metamorphism in the Sobrado unit under intermediate-P conditions, and related to intrusive magmatism and coeval burial in a magmatic arc setting. A maximum depositional age for the Sobrado unit is established in the late Cambrian (?511?Ma). The zircon dataset also record several inherited populations. The youngest cogenetic set of zircons yields crystallization ages of 546 and 526?Ma which are thought to be related to the peri-Gondwanan magmatic arc. The additional presence of inherited zircons older than 1000?Ma is interpreted as suggesting a West African Craton provenance.
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En línea:
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https://eprints.ucm.es/id/eprint/63394/1/Unraveling%20the%20origins%20and%20P-T-t%20evolution%20of%20the%20allochthonous%20Sobrado%20unit%20%28%C3%93rdenes%20Complex%2C%20NW%20Spain%29%20using%20combined%20U%E2%80%93Pb%20titanite.pdf
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