Algumas idades Rb-Sr e K-Ar de rochas granitóides da região de Vilarinho da Castanheira-Foz do Sabor (Carrazeda de Anciães-Nordeste de Portugal)

In this work present some Rb/Sr and K/Ar isotopic determinations of absolute ages in granitoids rocks of the AlijoCarvicais antiphorme, correspondent to the region at east-southeast of Carrazeda de Anciaes (Vilarinho da Castanheira-Foz do Sabor) The whole rock of the Castedo-Cabanas de Cima and Zedes-Cabeca Boa-Especiarias granites, placement indiferenciated, furnished the Rb/Sr conventional ages of 361.1±23.8 and 404.7±22.3M.a., with inicial rate (Sr/Sr)i=0.705±0.002. Their biotits gived the K/Ar apparent ages of 284.5±9.3 and 313.9±8.3M.y. The Vilarinho da Castanheira granite, very sheared during the D3 variscan phase deformation, furnished a whole rock Rb/Sr exact isochron diagram, in four samples, computed in 326.3±59.2M.y., with initial rate (Sr/Sr)i=0.7112±0.0059 (errors 95% confidence level) and MSWD=0.151158. Their biotits gived the K/ar apparent age of 306.4±11.0M.y. One of the K/Ar apparent ages (284.5±9.3M.y.) reflect the finished of the variscan regional metamorphism, possibiliting to give the finish of the consolidation of the variscan granitoids rocks and the influence of the late vaiscan shears. However, the other two seem to confirm the Rb/Sr isocronic age of the Vilarinho da Castanheira granite.