Abati Gómez, Jacobo and Dunning, Gregory R. and Arenas Martín, Ricardo and Díaz García, Florentino and González Cuadra, Pablo and Martínez Catalán, José Ramón and Andonaegui Moreno, Pilar (1999) Early Ordovician orogenic event in Galicia (NW Spain): evidence from U–Pb ages in the uppermost unit of the Ordenes Complex. Earth and Planetary Science Letters , 165 . pp. 213-228. ISSN 0012-821X
New U–Pb data (zircon, monazite and rutile) obtained from rocks of the uppermost allochthon in the Variscan belt of NW Spain indicate that the hangingwall to the suture includes an allochthonous unit with a pre-Variscan tectonothermal evolution. 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 to the igneous intrusions requires convergence and crustal thickening in order to generate the Barrovian facies pattern shown by the lithologies of the uppermost allochthon. The almost coeval magmatism and metamorphism, and the chemistry of the metabasites suggest an accretionary complex, probably related to a volcanic arc, as the most probable setting for the origin of the uppermost unit. The implications of the existence of Early Ordovician convergent plate boundaries are discussed in the context of Gondwana–Laurentia–Avalon interactions.
|Uncontrolled Keywords:||U/Pb; Geochronology; Ordovician; Thermal metamorphism; Hercynian orogeny; Galicia Spain|
|Subjects:||Sciences > Geology > Petrology|
|Deposited On:||10 Dec 2012 12:47|
|Last Modified:||10 Dec 2012 12:47|
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