Petrogenetic links between granites and pegmatite in the Fregeneda-Almendra area ( Salamanca, Spain and guarda, Portugal): new insights from 40Ar/39Ar dating in micas

Resumo

The Fregeneda-Almendra pegmatite fi eld (Spain-Portugal) is characterized by the occurrence of numerous pegmatites of different types. Most of these pegmatites are barren, but Li- and/or Sn-rich bodies are also abundant in the northern part of the fi eld. These pegmatites show a zonal distribution, with the degree of evolution increasing northwards relative to the Meda-Penedono-Lumbrales granite. 40Ar/39Ar geochronology in micas associated to all the pegmatite types, as well as to the granite suggests that the Li-rich pegmatites are not genetically related to the Meda-Penedono-Lumbrales granitic complex, whereas the Sn-rich dykes and the barren pegmatites could be related with the latest facies of this granite.