Encontrados 4 documentos, a visualizar página 1 de 1
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and b...
Pereira, M. Francisco; Chichorro, M.; Silva, J. Brandão; Ordonez-Casado, B.; Lee, James K.W.; Williams, Ian S.New U–Pb and 40Ar–39Ar geochronology and structural data from high- tomedium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465±14Ma (Middle Ordovician) measured on migmatite from the Coimbra–Cordoba shear zone is inte...
Zircon U–Pb geochronology of paragneisses and biotite
Pereira, M. Francisco; Chichorro, Martim; Williams, Ian S.; Silva, Jose B.Sensitive high-resolution ion microprobe U–Th–Pb age determinations on detrital and inherited zircon from the E ´ vora Massif (SW Iberian Massif, Portugal) provide direct evidence for the provenance of the Ossa–Morena Ediacaran basins (Se´rie Negra) and a palaeogeographical link with the West African craton. Three samples of the Se´rie Negra paragneisses contain large components of Cryogenian and Ediacaran (c. ...
Cambrian ensialic rift-related magmatism in the Ossa-Morena Zone
Chichorro, Martim; Pereira, M. Francisco; Diaz-Azpiroz, M.; Williams, Ian S.; Fernandez, C.; Pin, Ch.; Silva, Jose B.The Late Ediacaran (c. 560–550 Ma) Série Negra sediments of the Évora–Aracena metamorphic belt, Ossa-Morena Zone, SW Iberian Massif, preserve a record of the erosion of an Avalonian–Cadomian magmatic arc and subsequent related turbiditic sedimentation. Detrital zircon from the Série Negra is characterized by predominantly Ediacaran and Cryogenian ages, with few Paleoproterozoic and Archean cores, and a marked l...
New insights from U–Pb zircon dating of Early Ordovician magmatism on
Sola, A. Rita; Pereira, M. Francisco; Williams, Ian S.; Ribeiro, Luisa; Neiva, Ana M.R.; Montero, Pilar; Bea, Fernando; Zinger, T.The Central Iberian–Ossa-Morena transition zone (SW Iberian Massif) represents a segment of the northern Gondwana margin with a long geodynamic evolution, characterized by the superposition of Cadomian and Variscan events. The Early Ordovician is mainly represented by porphyritic felsic volcaniclastic rocks (the Urra Formation) that pass up into a siliciclastic sediments typical of the Central Iberian Zone (Low...
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