Geochronological constraints on the magmatic and hydrothermal evolution of the tras-os-montes hercynian domain (Galica, Spain) : position of the AU, SN-W mineralizing events.

Abstract

International audienceThe study area is located in the Galicia-Trás-os-Montes Zone (GTMZ zone, Arenas et al. 1986, Fig. 1), that belongs to the internal zone of the Hercynian belt and is composed of a relative autochthonous and parautochthonous units overthrusted by allochthonous complexes (Ribeiro et al. 1990). This domain of Palaeozoic schists is affected by a low to high temperature – medium pressure metamorphism. These rocks exhibit a well-developed regional schistosity related to nappes emplacement (D1 and D2 events) and are affected by NS-trending crenulation lineation and folds (D3 event) The late D3 event is characterized by a high-temperature metamorphism leading to development of local migmatite. Both parautochthonous and allochthonous units are intruded by syn- and post-kinematic plutons. Four generations of granites (G1 to G4) are identified by their textural and geochemical characteristics and by crosscutting relationships. Gold deposits are spatially associated with the G3 granites whereas Sn-W deposits are represented, in the study area, by disseminated and vein-type mineralization spatially close to the G2 granites (fig. 1)