Late variscan granite pluton of Vila Pouca de Aguiar( Northern Portugal): an example of low 87Sr/86Sr felsic granites

• Type: Article in International Scientific Journal
• Date: 2006

Authors

H. C. B. Martins (Author) FCUP; F. Noronha (Author) FCUP

Journal

Title: Geochimica et Cosmochimica Acta

Vol. 70 No. 18

Pages: A395-A395

ISSN: 0016-7037

Publisher: Elsevier

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Abstract (EN): The Vila Pouca de Aguiar pluton (VPA) is an example of late to post-orogenic felsic Variscan granites in northern Portugal (NW of Iberian Peninsula). It is a composite and zoned pluton with three biotite monzogranites: Vila Pouca de Aguiar granite (VPAG), Pedras Salgadas granite (PSG) and Gouvães da Serra granite (GSG). The emplacement of this pluton, subsequent to the third Variscan deformation phase (D 3 ), was controlled by a regional tectonic structure, the Régua-Verin fault. The U-Pb zircon data define a normal discordia (MSWD = 1.28) with an upper intercept age of 299 ± 3 Ma which is in good agreement to the whole rock Rb-Sr ages of 299 ± 9 Ma and can be interpreted as the emplacement age of the pluton. The lack of a mechanism that could link the chemistry of these granites suggests an intervention of different processes and/or distinct sources in its genesis. The geochemical and mineralogical data (biotite and zircon) suggest that these granites, although displaying a common potassic sub-alkaline signature are not related to the same initial magma. This is supported by their contrasting isotopic compositions: 87Sr/ 86Sr i = 0.7067–0.7071 and &z.epsiv;Nd = −2.5 for VPAG, and Sr i = 0.7044–0.7050 and &z.epsiv;Nd = −1.9 to −2.0 for PSG. The VPA pluton granites are significantly less radiogenic in Sr but more radiogenic in Nd than most of the Variscan granitoid rocks of Iberia

Language: English

Type (Professor's evaluation): Scientific