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 New U-Pb SHRIMP zircon ages for pre-variscan orthogneisses from Portugal and their bearing on the evolution of the Ossa-morena tectonic zone
Please use this identifier to cite or link to this item http://hdl.handle.net/10773/13028

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
Iberian Massif
Ossa-Morena Zone
U-Pb geochronology
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.
URI: http://hdl.handle.net/10773/13028
ISSN: 0001-3765
publisher version/DOI: http://dx.doi.org/10.1590/S0001-37652006000100013
source: Anais da Academia Brasileira de Ciências
appears in collectionsGEO - Artigos

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