Publication: Evolución tectónica del Macizo Ibérico durante la orogenia Varisca: colisión
Gondwana - Laurrusia
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Publication Date
2016
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Sociedad Geológica de España.
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Abstract
La revisión de la evolución tectonometamórfica y magmática del Macizo Ibérico revela periodos de extensión y convergencia alternantes dentro de un proceso global de convergencia entre Gondwana y Laurrusia durante la formación de Pangea en el Paleozoico Superior. Fases dominadas por compresión a escala litosférica se caracterizan por el desarrollo de subducción oceánica y continental, generación de arcos magmáticos, cabalgamientos y procesos de acreción de litosfera continental y plegamiento. Eventualmente, la convergencia Varisca durante el Carbonífero produjo la transferencia de un conjunto de terrenos alóctonos peri-Gondwánicos, el denominado Alóctono Ibérico, sobre Gondwana. El Alóctono Ibérico muestra una impronta tectonometamórfica previa a ese proceso de transferencia fruto de la yuxtaposición temprana de Gondwana y Laurrusia tras el cierre del océano Reico en el Devónico Inferior. Las fases dominadas por fenómenos extensionales están representadas por la apertura de dos cuencas oceánicas efímeras a expensas de la corteza orogénica formada hasta el momento, primero en el Devónico Inferior-Medio, tras el cierre del Reico, y luego durante el Carbonífero Inferior, tras el emplazamiento del alóctono peri-Gondwánico. Seguidamente, un evento de extensión intra-orogénica durante el Carbonífero Inferior-Medio desmembró al Alóctono Ibérico en apilamientos individuales de unidades exóticas separados por fallas extensionales y domos. La tectónica transcurrente jugó un papel fundamental durante toda la orogenia Varisca, especialmente durante la creación de nuevos bloques tectónicos separados por zonas de cizalla transcurrentes intra-continentales en las últimas etapas de convergencia continental.
A review of the tectonometamorphic and magmatic evolution of the Iberian Massif reveals backs and forths in the overall convergence between Gondwana and Laurussia during the amalgamation of Pangea in Upper Paleozoic times. Stages dominated by lithosphere compression are characterized by subduction, both oceanic and continental, development of magmatic arcs, (over- and under-) thrusting of continental lithosphere, and folding. Variscan convergence resulted in the eventual transference of a large allochthonous set of peri-Gondwanan terranes, the Iberian Allochthon, onto the Gondwana mainland. The Iberian Allochthon bears the imprint of previous interaction between Gondwana and Laurussia, including their juxtaposition after the closure of the Rheic Ocean in Early Devonian times. Stages governed by lithosphere extension are featured by the opening of two short-lived oceanic basins that dissected previous Variscan orogenic crust, first in the Early-Middle Devonian, following the closure of the Rheic Ocean, and then in the Early Carboniferous, following the emplacement of the peri-Gondwanan allochthon. An additional, major intra-orogenic extensional event in the Early-Middle Carboniferous dismembered the Iberian Allochthon into individual thrust stacks separated by extensional faults and domes. Lateral tectonics played an important role through the Variscan orogenesis, especially during the creation of new tectonic blocks separated by intracontinental strike-slip shear zones in the late stages of continental convergence.
A review of the tectonometamorphic and magmatic evolution of the Iberian Massif reveals backs and forths in the overall convergence between Gondwana and Laurussia during the amalgamation of Pangea in Upper Paleozoic times. Stages dominated by lithosphere compression are characterized by subduction, both oceanic and continental, development of magmatic arcs, (over- and under-) thrusting of continental lithosphere, and folding. Variscan convergence resulted in the eventual transference of a large allochthonous set of peri-Gondwanan terranes, the Iberian Allochthon, onto the Gondwana mainland. The Iberian Allochthon bears the imprint of previous interaction between Gondwana and Laurussia, including their juxtaposition after the closure of the Rheic Ocean in Early Devonian times. Stages governed by lithosphere extension are featured by the opening of two short-lived oceanic basins that dissected previous Variscan orogenic crust, first in the Early-Middle Devonian, following the closure of the Rheic Ocean, and then in the Early Carboniferous, following the emplacement of the peri-Gondwanan allochthon. An additional, major intra-orogenic extensional event in the Early-Middle Carboniferous dismembered the Iberian Allochthon into individual thrust stacks separated by extensional faults and domes. Lateral tectonics played an important role through the Variscan orogenesis, especially during the creation of new tectonic blocks separated by intracontinental strike-slip shear zones in the late stages of continental convergence.