Un yacimiento de Au en carbonatos del Orógeno Hercínico: el área de Salamón (N León)

The Salamon gold prospect constitutes an example of carbonate-hosted gold deposit formed during the last events of the Hercynian orogeny. It is formed by a complex paragenetic sequence of AuAs- Sb-Hg-Cu-Ni-Co-Pb-Zn-U minerals in jasperoid and quartz-dolomite host rack. Au correlates positively with As at single crystal scale in pyrite and arsenopyrite. Fluid inclusion studies and arsenopyrite geothermometry show temperatures in the range 140-280° at 350-400 bars. Stable isotope data suggest reduction of sulfur from marine evaporites and buffer of carbon in the fluid by the host carbonates. The age of the deposit is 269 ± 5 m.y. accroding U-Pb determination on uranite grains, which is consistent with an uranite age from Villamarin and with age determinations of intrusive rocks spatially associated to several ore deposits in the area.