Caracterización de los fluidos hidrotermales en el área Chispas, este del Macizo del Deseado, provincia de Santa Cruz

GUIDO, D.

Río Cuarto

Congreso; VII Congreso de Mineralogía y Metalogenia (Minmet); 2004

Hydrothermal fluids of the Chispas area were characterized with fluid inclusions and oxygen and sulphur stable isotopes from the Stockwork quartz veinlets. These studies point out that the composition of the mineralising fluids in Chispas area had formed in an H2O-NaCl system, without CO2 in the vapour face, at an estimated temperature (Th) of 285°C and a 4.86 wt% NaCl salinity. The oxygen isotope composition (δ18OSMOW=-5.05?) shows that fluids had an important meteoric input, with affinities to local meteoric waters (-6 to -11?). Sulphur isotope (δ34Sfluid=0,02?) indicates that S source is related with middle to upper Jurassic volcanism (Bahía Laura Group and Bajo Pobre Formation). The low content of δ18O, together with the high Th of Chispas, allow to interpret that this deposit is relatively deep if compared with the rest of the known Deseado Massif epithermal deposits. Also a deepness estimation of 800 m below surface was done. Considering salinities of Chispas and Deseado Massif epithermal deposits, it can be concluded that hydrothermal fluids of the Deseado Massif are characterized by a higher salinity than classic low sulfidation deposits.