%0 Journal Article
%A Gómez Barreiro, Juan
%A Martínez Catalán, José Ramón
%A Díez Fernández, Rubén
%A Arenas Martín, Ricardo
%A Díaz García, Florentino
%T Upper crust reworking during gravitational collapse:the Bembibre–Pico Sacro detachment system(NW Iberia)
%D 2010
%@ 0016-7649
%U https://hdl.handle.net/20.500.14352/44358
%X The kinematics of the basal allochthon in the SW of the O´ rdenes Complex is analysed to constraintits evolution during collisional and postcollisional stages of the Variscan orogeny. Two distinct sequences havebeen identified in the basal allochthon of this sector: the upper and lower sequences, in close correlation withthe subdivision of the basal allochthon in the Malpica–Tui Complex. Three main tectonic episodes have beenestablished in the basal allochthon: a high-pressure event related to continental subduction, a mesozonal eventof regional exhumation by thrusting and recumbent folding, and a regional-scale extensional episode thatresulted in the development of the Bembibre–Pico Sacro detachment system. The Bembibre–Pico Sacrosystem rejuvenated pre-existing shear zones, whose weakness favoured the nucleation of the detachments.Shear zones associated with the detachments overprinted the previous tectonic fabrics under conditionsranging from lower amphibolite to greenschist facies, and with heterogeneously distributed ductile to brittledeformation. The detachment system is coeval with late orogenic collapse and widespread magmatism, andrepresents its upper crustal expression. It correlates with mid- and lower crustal flow and the development ofgneiss domes at depth in such a way that the basal allochthon can be considered a rheological boundarybetween the more rigid allochthonous sequences above and the more viscous Schistose Domain andautochthon below.
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