Summary:
Deposit type
The Warintza deposit is a classic calc-alkaline porphyry copper–molybdenum (Cu-Mo) system, consistent with models described by Lowell & Guilbert (1970) and Sillitoe (2010). Mineralization is hosted in multi-phase intrusive complexes, primarily diorite to quartz monzonite porphyries, and in associated hydrothermal breccias. Copper and molybdenum occur as disseminations and in quartz-sulphide veinlet stockworks, as well as within breccia matrix sulphides.
Hydrothermal alteration follows the typical porphyry zonation pattern: a central potassic core (biotite, K-feldspar) associated with higher grades, overprinted by phyllic (quartz–sericite–pyrite) assemblages, and surrounded by a broad propylitic halo (chlorite–epidote). Structural control through fracture networks enhances sulphide emplacement, and supergene processes have contributed to some secondary copper enrichment near surface.
Warintza cluster
The Warintza cluster consists of a series of discrete to partially coalescent porphyry Cu-Mo±Au deposits and prospects, including Warintza Central, Warintza East, Warintza Southeast, Patrimonio, Warintza West, and Warintza South. Among these, Warintza Central, Warintza East, Warintza West, Warintza Southeast, and Patrimonio are the most advanced in terms of exploration. Several Cu-Mo soil geochemical anomalies within the area are interpreted as representing additional porphyry-style mineralization, with the broader mineralized footprint covering approximately 30 km².
At Warintza Central, porphyry Cu-bearing dikes and stocks were emplaced into earlier plutonic rocks. In contrast, at Warintza East and Warintza South, the porphyry intrusions cut Misahuallí volcanic and volcano-sedimentary strata. Warintza West hosts porphyry-style mineralization within a magmatichydrothermal stockwork that overprints a quartz monzodioritic intrusion emplaced into a composite dioritic to granodioritic pluton.
Warintza Central
The east-trending Warintza Central porphyry Cu deposit is hosted within a series of composite intrusive stocks comprising two principal pre-mineral units: an upper quartz monzodiorite and a lower diorite. Both intrusive bodies were emplaced into volcanic and volcano-sedimentary rocks of the Misahuallí sequence. The quartz monzodiorite is typically fine-grained and equigranular in texture, although hydrothermal alteration has extensively overprinted its original mineralogy. In contrast, drill core from depth within the diorite unit reveals preserved primary textures, including hornblende and biotite.
Numerous dike-like porphyry intrusions are present throughout Warintza Central and its eastern extensions. These typically exhibit coarse-grained textures, with abundant plagioclase and hornblende phenocrysts and lesser quartz eyes in a fine- to aphanitic-grained groundmass of andesitic to dacitic composition. These porphyries occur as narrow dikes that may coalesce into more substantial intrusive bodies.
Two main porphyry phases have been recognized:
• Early to inter-mineral porphyries, generally andesitic to dacitic, are variably altered and intersected by classic porphyry-style veinlets including early dark micaceous (EDM), A-, B-, C-, and D-type varieties;
• Late-mineral porphyries are typically dacitic, marked by well-developed quartz eyes, aphanitic groundmass, and a relatively fresh appearance, characterized by weak illite alteration. These later intrusions generally lack veining, although local pyrite-rich, D-type and polymetallic veinlets may occur.
Alteration and mineralization
The alteration includes an early potassic and green-gray mica (chlorite–fine-grained muscovite) assemblage, with overprinting by pyrite-rich, fine-grained white mica (sericite) alteration and base-metal-bearing veinlets. Sulphides are leached in the upper levels of the system and copper is enriched below this layer in a supergene zone. The grade distribution of the copper mineralization in the supergene is interpreted as having a gradational contact with the underlying hypogene.
Hypogene sulphide zoning
Warintza Central exhibits a well-defined sulphide zoning pattern, characterized by systematic vertical and lateral variation in chalcopyrite and pyrite distribution. In the upper and shallower portions of the deposit, all alteration-mineralization stages — ranging from early EDM halos through A-, B-, and C-type veinlets — are consistently dominated by pyrite relative to chalcopyrite. In contrast, the central and middle zones of the system, particularly its interior portions, are chalcopyrite-rich, with CPYPY ratios typically ranging from cpy > py to cpy approximately equal to (˜) py across all copper-bearing alteration events.
Supergene enrichment
The upper levels of Warintza Central exhibit evidence of an early-stage, immature supergene chalcocite blanket developed beneath an irregular leached capping. This capping zone may be only a few metres thick in places but, where more fully developed, is underlain by a more coherent and thicker chalcocite-enriched horizon.
Eastern extensions
Copper is predominantly hosted as chalcopyrite within east-trending swarms of C-type veinlets. The presence of garnet-bearing prograde skarn and retrograde epidote-chloritemagnetite-pyrite-chalcopyrite assemblages confirms the relatively proximal setting of these rocks within the thermal aureole of Warintza Central. The skarns formed through metasomatic alteration of specific volcano-sedimentary horizons in the Misahuallí sequence.
Warintza East
Warintza East is interpreted as a distinct centre along the Warintza trend based on its geological characteristics and alteration-mineralization features. The causative porphyry intrusions are predominantly felsic in composition, represented by discrete, coarse-grained rhyodacitic bodies rich in quartz eyes. These intrude thinly-bedded to laminated, shallow-dipping, fine-grained volcaniclastic rocks of the Misahuallí sequence, as well as units of the Andesitic Centre (referred to as the Andesite Porphyry Centre). The rhyodacitic intrusions exhibit moderate to intense molybdenum-bearing quartz stockworks, primarily composed of B-type veinlets. Copper concentrations are notably lower in the rhyodacite compared to the surrounding andesitic host rocks, which contain more abundant chalcopyrite. This distribution indicates a zoned mineralization pattern at Warintza East, with a molybdenum-rich core surrounded by a broader Cu-Mo halo.
Andesite porphyry centre
The area between Warintza Central and Warintza East includes a composite, coarse-grained, porphyritic andesite intrusion intruded by fine-grained, aphanitic dikes of similar composition. Both are overprinted by fine-grained, hydrothermal biotite alteration. A fine- to medium-grained porphyry, commonly intersected at depth in most drillholes in the eastern part of Warintza East, displays broad textural zoning, with coarser grain size concentrated in its central portions. This phase is marked by numerous thin, hairline fractures and veinlets composed of chlorite, biotite, and quartz, which are themselves cut by sulphide-poor A-type and molybdenum-bearing B-type veinlets.
Warintza West
Warintza West is hosted by a magmatic-hydrothermal stockwork zone formed within a series of tonalitic to quartz-monzodioritic intermineral porphyries as magmatic and hydrothermal breccias emplaced into a composite, dioritic to granodioritic pluton. The alteration includes an early potassic and green-grey mica (green sericite) assemblage, with overprinting by pyrite-rich, fine-grained, white mica (sericite) alteration and minor advanced argillic alteration. Hypogene mineralization is mainly composed of pyrite, chalcopyrite, and scarce covellite. A limited supergene zone of copper enrichment exists above the hypogene zone, with the copper and molybdenum grade populations indicating a gradational change between supergene and hypogene.