Summary:
The Yauli unit region shows mineralization related to polymetallic epithermal systems, replacement bodies and polymetallic vein systems, as well as porphyry mineralization and skarns, thus indicating the great potential of the area.
The Ticlio stock, cropping out in the western part of the Morococha district, which located in the northwestern sector of the Yauli Dome, and sharing mineralization and alteration features with shallow-level porphyry Cu-Au deposits, is atypical for this area where Cu-Mo porphyry systems are predominant (e.g., the giant Toromocho porphyry Cu-Mo deposit; Lowell and Alvarez 2005; Kouzmanov et al. 2008). The Ticlio magmatichydrothermal system consists of a single porphyritic stock with granodioritic composition in the center of which a stockwork of dense quartz-magnetite, quartz and hairline magnetite veinlets was developed. Several hydrothermal alteration zones, typical of porphyry Cu systems, overprinted the stock.
The Ticlio stock is a single granodioritic intrusion emplaced during the Late-Miocene between the Anticona diorite and Cretaceous dolomitic limestones of the Jumasha Formation. The intrusion covers about 0.25 km2 at surface. A series of basaltic xenoliths marks the eastern and southeastern fringe of the intrusion. An intrusive contact with the Anticona diorite delimits the stock to the east. A 10 cm-thick porphyritic dike trending N70-75 and several aplitic dikes having almost the same orientation crosscut the Ticlio intrusion. Three systems of fractures (NE-SW, WNW-ESE and less important NS) host porphyry-style quartz-magnetite veins. Some of the NE-SW faults host also some late polymetallic mesoepithermal veins.
A core of high-density stockwork of quartz-magnetite±K-feldspar veins changes progressively to an outer zone of intense Kfeldspar alteration with a low-density of magnetite and quartzmagnetite veinlets that host small amounts of bornite and native Au inclusions in chalcopyrite. An outermost zone displays a strong pyrite-quartz-sericitic alteration and skarn mineralisation in adjacent Cretaceous carbonate rocks (Bendezú et al. 2008a; Chevalier 2010).
The Ticlio granodiorite is characterized by phenocrysts of plagioclase (~25-30%), biotite (~5-10%), quartz (~3- 7%) and magnetite (<1%). The phenocrysts are set in aplitic, medium-grained groundmass consisting of Kfeldspar (40-60%), quartz (40-50%) and albite (<10%). The predominant phenocrysts consist of plagioclase, generally euhedral and uniform in size (2-3 mm) with complex compositional zoning. Quartz phenocrysts (0.5- 5 mm across) are usually rounded, commonly containing small inclusions of other minerals. Magmatic biotite forms euhedral grains with a typical length of 0.5-5 mm. Magmatic hornblende is completely pseudomorphed by hydrothermal biotite. Zircon and apatite are ubiquitous accessory phases, set in the groundmass, or as inclusions in the euhedral phenocrysts.
Mineralization and alteration at Ticlio developed in four main stages: (i) an early stage of biotite ± Kfeldspar (potassic) alteration, accompanied by a dense quartz or quartz-magnetite stockwork zone, developed in the central part of the stock; (ii) a transitional stage consisting of chlorite ± epidote ± hematite affects principally the SW fringe of the intrusion; (iii) a phyllic alteration zone developed on the southern periphery of the stock; and (iv) illite-sericite alteration related to the formation of late polymetallic meso-epithermal veins overprints the porphyry-style mineralization and alteration.
Along the contact with Cretaceous carbonate sedimentary rocks, at the western border of the intrusion, a narrow zone of endo- and exoskarn developed, both dominated by garnet-diopside assemblages. In the endoskarn, hydrothermal titanite is commonly intergrown with diopside. Late epidote ± carbonate veinlets overprint the anhydrous assemblages.
Drilling campaigns
The 2023 and 2024 drilling campaigns aimed to enhance the geological certainty of mineral resources. Additionally, exploratory drilling sought to identify new economic resources and assess areas with promising geological and economic potential, thereby extending the longevity of the assets in the medium to long term.
In Ticlio, geological certainty is increased in the deepening of the Ramal Techo vein, and new economic resources are delineated over Cuerpo Reemplazamiento. Geochemical results record high grades of zinc, lead, and silver, ensuring the operational continuity of the Ticlio mine in the coming years. Additionally, exploration is being conducted in new areas with high geological potential near the operation, such as the Giuliana-Reina-Katti vein systems and large-tonnage polymetallic bodies.
In 2024, new areas with high geological potential near the operation have been explored, such as the Sherzone vein and polymetallic bodies (Ariana), with high expectations of consolidating their discovery in 2025.