Abstract

LOAIZA, Diego; ALVARAN-ECHEVERRI, Mauricio  and  LLANOS, Juan Sebastián. Pétrographie, metallographic, microthermometric characterization of the mineralizations and hydrothermal alterations of the Campana prospect (Cu-Au±Mo Porphyry), in Pácora (Caldas, Colombia). Bol. geol. [online]. 2025, vol.47, n.2, pp.61-81.  Epub Sep 16, 2025. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v47n2-2025003.

The Campana prospect is a porphyry-type Cu-Au (±Mo) deposit, located within the Miocene Middle Cauca Belt, in the municipality of Pácora, Caldas. It is located across the Romeral fault system, which is a suture that contacts rocks of continental affinity to the east with rocks of oceanic affinity to the west. In this prospect, 4 main stages of intrusions associated with the development of magmatic-hydrothermal breccias were identified from petrographic and metallographic studies. Each phase induced various hydrothermal alteration assemblages of sodium-calcic, potassic, propylitic, phyllic (sericitic quartz), intermediate argillic and advanced argillic type, although telescoping processes locally disrupted the stratigraphic order in certain zones of the prospect. The mineralization presents: i) sulfides and sulfosalts, such as, pyrite, chalcopyrite, sphalerite, galena, tetrahedrite-tennantite and freibergite; ii) oxides, predominantly magnetite, hematite and, Ti-bearing dioxides; and iii) native elements such as gold, silver, electrum. These occur in mineralization styles ranging from disseminations, veinlets of different types, to replacements and inclusions. The microthermometric data on fluid inclusions obtained in the different types of veinlets, presented homogenization temperatures ranging from 530.1°C to 296.6°C and salinities between 50.09% and 0.177% wt. eq. NaCl. The wide range of salinity and homogenization temperature suggests that the genesis of the deposit begins with a magmatic-hydrothermal stage, characterized by the higher temperatures obtained in this study, and ends with a shallower and lower temperature late epithermal stage. All this allows concluding that this zone represents a complete porphyritic system, from the internal intrusive part to the shallower stages or zones represented by zones characterized by low- to intermediate-sulfidation epithermal veins, which are consistent with those reported worldwide for this type of deposits.

Keywords : Middle Cauca Belt; Romeral Fault System; Salinity; Sulfides; Native elements; Homogenization temperature.

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