%0 Journal Article
%A Abati Gómez, Jacobo
%A Dunning, Gregory R.
%A Arenas Martín, Ricardo
%A Díaz García, Florentino
%A González Cuadra, Pablo
%A Martínez Catalán, José Ramón
%A Andonaegui Moreno, María Del Pilar
%T Early Ordovician orogenic event in Galicia (NW Spain): evidence fromU–Pb ages in the uppermost unit of the Ordenes Complex
%D 1999
%@ 0012-821X
%U https://hdl.handle.net/20.500.14352/57752
%X New U–Pb data (zircon, monazite and rutile) obtained from rocks of the uppermost allochthon in the Variscan belt ofNW Spain indicate that the hangingwall to the suture includes an allochthonous unit with a pre-Variscan tectonothermalevolution. This evolution is characterised by an Early Ordovician (498–500 Ma) bimodal magmatism followed almost immediately(493–498 Ma) by a Barrovian style metamorphism up to the granulite facies. The metamorphism subsequent tothe igneous intrusions requires convergence and crustal thickening in order to generate the Barrovian facies pattern shownby the lithologies of the uppermost allochthon. The almost coeval magmatism and metamorphism, and the chemistry of themetabasites suggest an accretionary complex, probably related to a volcanic arc, as the most probable setting for the originof the uppermost unit. The implications of the existence of Early Ordovician convergent plate boundaries are discussed inthe context of Gondwana–Laurentia–Avalon interactions.
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