Two mineral deposit models are proposed for La Parrilla: intrusion-related carbonate replacement deposits and mesothermal fault-veins.
Mineralization occurs as vein and replacement deposits, the locations of which are structurally controlled by pre-existing faults, fractures, and bedding planes. Veins can be either open space filling, forming massive sulphide and breccia veins, or fault-related, consisting of matrix-supported breccias or gouge containing disseminated sulphides and oxides. Gradations commonly occur between the two types in any vein system. Stockwork veining can occur at country rock/vein contacts. Replacement deposits occur as oblique or perpendicular splays to veins and faults, and as larger replacement deposits concordant with sedimentary bedding.
La Parrilla deposits contain primary sulphides such as galena, sphalerite, pyrite, pyrrhotite, arsenopyrite, chalcopyrite, covellite, acanthite, native silver, and silver sulphosalts (tetrahedrite freibergite- solid solution). Due to supergene oxidation, the primary sulphides in the upper parts of some deposits have been altered to cerussite, anglesite, hemimorphite, hydrozincite, jarosite, goethite, hematite, cervantite, malachite, chrysocolla, chalcanthite, and native silver.
The major mineralized zones are:
• Rosarios vein: strikes north 70 degrees (°) west on average, dips at 64° to the northeast (290°/64°) and has a known strike length of 2 kilometres (km). The mineralizat ........