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New microthermometric data combined with stable isotope geochemistry and paragenetic relationships support a previously suggested cooling-mixing model for the iron oxide-copper-gold mineralization in the Mantoverde district. Fluid inclusions show characteristics of a CO 2 -bearing aqueous NaCl±CaCl 2 salt system. The evolution of the Mantoverde hydrothermal system is characterized by (1) an early hypersaline, high to moderate temperature fluid; (2) a moderate saline, moderate temperature fluid; and (3) a low saline, moderate to low temperature fluid. Early magnetite formation took place at median temperatures of 435.0°C, whereas hematite formed at median temperatures of 334.4°C. The main sulfide mineralization texturally post-dates the iron oxides and occurred before late-stage calcite, which developed at a median temperature of 244.8°C. Boiling occurs only locally and is of no relevance for the ore formation. The microthermometric and stable isotope data are supportive for a fluid cooling and mixing model, and suggestive for a predominantly magmatic-hydrothermal fluid component during the iron oxide and main sulfide mineralization. Thereafter, the incursion of a nonmagmatic fluid of ultimately meteoric or seawater gains more importance.

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