Epithermal vein system of the Josefina prospect, Deseado Massif, Patagonia Argentina

MOREIRA, P.; FERNÁNDEZ, R.; SCHALAMUK I.B.A

Digging Dipper

S.J. Andrew et al. Eds

Lugar: Dublin (Irlanda); Año: 2007; p. 711 - 714

The central sector of the La Josefina Au-Ag Prospect contains eight structurally controlled quartz veins hosted in middle to upper Jurassic volcaniclastic rocks. The alteration and vein minerals, Au/Ag ratios, fluid inclusion temperatures and salinity results indicate that La Josefina is an epithermal occurrence. The stable isotopic compositions of the quartz point to an important meteoric water component. The d34S value of barite indicates sulphate was derived from a magmatic source. The bimodal volcanism and extensional tectonic setting of the Deseado Massif and the attributes of the veins (structural control, hydrothermal alteration, banded quartz textures and late carbonate-replacement texture) are consistent with the low sulphidation model. Alternatively, the barite, specular hematite, and abundance of thick comb texture quartz are characteristic of the intermediate sulphidation model.