Las mineralizaciones intragraníticas de Uranio en el batolito de Cabeza de Araya (provincia de Cáceres)el Saguazal, Brechas NNE y La Zafrilla

Resum

The U mineralizations within the most evolved granitic faciès of the Cabeza de Araya batholith are controlled by reverse faults, N120-130E (El Saguazal), or by subvertical ones, NNE (La Zafrilla). Two different paragenesis have been identified in these mineralizations separated by a brecchiation process. The second one is rich in U and is constituted by pyrite, pitchblende (gummites) and cryptocrystalline silica. This paragénesis is typical of the U epithermal deposits with quartz or jasper, which are the best ones represented in the Hesperian Massif. The origin of the mineralizations is related to the remobilization, transport and redeposition of the disperse U in the host granites. This is a consequence of the joint action or the granite weathering and the hydrothermal stage associated with the development of huge sinistral strike-slip faults that, with a NNE direction, affected the zone. Consequently, it can be assumed that the first U mineralizing process ocurred in the Permian. That is, after the faults had become inactive at the beginning of the Triassic period. The possibility of remobilizations during the intrusion of the NNE basic dykes and the alpine fracture-type tectonic cannot be put aside.