High and intermediate sulphidation environment in the same hydrothermal deposit: the example of Au-Cu Palai–Islica deposit, Carboneras (Almería)

Two epithermal environments have been identified in the Miocene Palai–Islica Au–Cu deposit: A) Intermediate sulphidation, hosted mainly in quartz veins, comprises pyrite, chalcopyrite, sphalerite and galena as the major sulphides, which are accompanied by a variety of Ag-bearing accessory minerals. Au–Ag alloys are the only gold-bearing phase. The veins are enclosed by sericitic and chloritic alteration. Fluid inclusions in quartz, sphalerite and calcite give Th between 118–453 ºC, and salinities between 0.2–51.4 wt.% NaCl eq, with high salinities being related to high-grade mineralisation. Stable isotopes indicate magmatic and marine fluids. B) High sulphidation consists of massive host rock silicification with disseminated pyrite and minor chalcocite, covellite, native copper and native gold. The surrounding alteration is advanced argillic/argillic in style. Fluids have Th between 224–381 ºC have salinities between 0.4 and 41.1 wt.% NaCl eq. The stable isotope data demonstrate the dominance of magmatic fluids, and disproportion processesUniversidad de Granada. Departamento de Mineralogía y PetrologíaGrupo de Investigación de la Junta de Andalucía RNM-0131.Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR)The research has been supported by the project BTE 2001-3308 of DGI of Ministerio de Ciencia y Tecnología of Spain and the RNM 0131 Research Group of Junta de Andalucía. AJB is funded by NERC support of the Isotope Community Support Facility at SUERC