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|title: ||New U-Pb SHRIMP zircon ages for pre-variscan orthogneisses from Portugal and their bearing on the evolution of the Ossa-morena tectonic zone|
|authors: ||Cordani, U. G.|
Nutman, A. P.
Andrade, A. S.
Santos, J. F.
Azevedo, M. do Rosário
Mendes, M. H.
Pinto, M. S.
|keywords: ||Cadomian orogeny|
|issue date: ||2006|
|publisher: ||Academia Brasileira de Ciências|
|abstract: ||New SHRIMP U-Pb zircon ages for the Portalegre and Alcáçovas orthogneisses document a complex pre-Variscan history for the Iberian basement in Portugal. The available geochemical and geochronological data for the Alcáçovas orthogneiss (ca. 540 Ma) tend to favor its involvement in a Cadomian orogenic event. This is consistent with the development of an active continental margin setting at the end of the Proterozoic and supports a Gondwanan provenance for the Iberian crust. On the other hand, the Ordovician emplacement age obtained for the magmatic precursors of the Portalegre orthogneisses (497 ± 10 Ma) provides additional evidence for the occurrence of rift-related magmatic activity during the Lower Paleozoic.|
|publisher version/DOI: ||http://dx.doi.org/10.1590/S0001-37652006000100013|
|source: ||Anais da Academia Brasileira de Ciências|
|appears in collections||GEO - Artigos|
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