Lithogeochemistry of the El Valle disseminated gold deposits, Asturias, NW-Spain

The aim of this paper is to present the geochemical characterization of a suite of subvolcanic dykes and associated alterations of their host-rock in the disseminated gold deposit of the El Valle. From the lithogeochemical study, two different types of felsic subvolcanic rocks are distinguished and are probably the result of compositional gradients in the magma chamber due to crystal-melt fractionation and liquid-fractionation processes. Moreover, the elemental fluxes during the associated alterations indicate a decarbonation process accompanied by silicification and argillization of K-Al-bearing phases. This may be accompanied by iron released from reactive Fe-bearing minerals and the precipitation of disseminated arsenian pyrite and arsenopyrite with "invisible gold" during a sulphidation proccess.