Fig. 4: Schematic model for the Candelaria IOCG district.
a Slow cooling of a dioritic intrusion and separation of a fluid phase, coalescence of the fluid phase, and encapsulation of magnetite microlites to form a magnetite-fluid suspension accumulation under overpressure conditions that scavenges Fe, Cu, Au, S, and Cl57, 58. b The accumulated fluid is sporadically “tapped” by active, deep crustal sinistral strike-slip faults initially associated with the formation of the sedimentary basin. Fault movement allowed the ascent of high-temperature Fe-rich fluids. c Further fault movement would allow the ascent of (Cu, Fe)-rich fluids; Cu in the fluid increases due to increased solubility of CuCl at ~650 °C. d Fluids cooling to temperatures of about 600 °C; further cooling to ~500 °C of the ascending hydrothermal fluids by convection causes Cu precipitation. Peak chalcopyrite mineralization occurs at temperatures of ~400 °C. At the final stage, hydrothermal fluids would have interacted with external, basin derived fluids, which would have added reduced sulfur into the system in the form of pyrite but no important Cu mineralization20. *Depth estimated for pressure conditions of 100 MPa.
