Geochemical and metallogenic model of the santa fe sn-zn-pb-ag-(in) deposit in the central andean tin belt

Zusammenfassung

The Santa Fe mining district is located in the Central Andean tin belt and contains several Sn-Zn-Pb-Ag deposits. From the economic point of view, the most important deposits of the district are Japo, Santa Fe and Morococala. Beyond the traditional metal commodities, Central Andean Tin Belt could become an exploration target for indium, owing to the potential of the ore-bearing paragenesis to contain high concentrations of this technology-critical element. Notwithstanding the foregoing, important features about genesis and fluids evolution have been poorly studied. This work presents a reinterpretation of the Santa Fe deposit as a greisen deposit based in fluid inclusions and isotopic data, as well as, an extensive and accurate fieldwork. In the Santa Fe district, the ore mineralization occurs as two main styles: (a) Sn-rich mineralization, represented by cassiterite-quartz veins, and (b) Zn-Pb-Ag mineralization, represented by sphalerite, galena and stannite group phases. The In contents in igneous rocks are between 1.5 and 2.5 ppm, whereas in the ore concentrate it attains up to 200 ppm. The 1000×In/Zn ratio ranges from 25 up to 4000. Exceptionally high In values were found in sakuraiite (2.03 wt.%). Sakuraiite in this deposit show evidences for a link between stannite¿kësterite solution. Thus, there is an important relationship between stannite group and sulfosalts. Likewise, an important number of metal associations, including base, alloy, noble and critical metals, have been found in this ore deposit. There is a noteworthy exploration potential for these metals in the Santa Fe District and even in similar deposits also elsewhere in the Central Andean tin belt.