Projects
OVERVIEW
The Domeyko Sulfuros Project is an exploration property situated in the Atacama Region of northern Chile, approximately 150 kilometers north of the city of La Serena and 54 kilometers south of Vallenar. The project encompasses 75 mining concessions, covering an area of 10,056 hectares within the Dos Amigos mining district.
The Domeyko Sulfuros Project benefits from outstanding accessibility due to its strategic location near the Pacific coast and low-altitude setting. Its proximity to the Pan-American Highway and to the Domeyko Townville provides convenient access to electrical power, water, and logistic support to the exploration project. These positive features enable year-round exploration activities.
The primary objective of the project is to investigate at least three Cu-Au porphyry targets and one mineralized hydrothermal breccia, with a focus on delineating primary Cu-Au resources.
PROJECT HISTORY
The ‘Program for Development,’ financially supported by the United Nations, is responsible for the earliest exploration work in the district, carried out during the timeframe from 1962 to 1964. With the goal of assessing the porphyry copper potential of the area, a 1:10,000 scale geological reconnaissance mapping of the Dos Amigos and Tricolor targets was conducted, along with IP and resistivity surveys. Five shallow drill holes were executed at Tricolor, with results indicating the presence of low-grade primary copper mineralization, with concentrations ranging from 0.13 to 0.32 percent within specific intervals.
Between 1968 and 1971, the governmental institution ‘Corporación Nacional de Fomento’ (CORFO) conducted an exploration campaign that involved geological studies and 47 drill holes. This program identified a supergene copper enrichment zone, for which a resource of 3.5 million tons, averaging 1.18% Cu was estimated.
During the period from 1976 to 1980, Noranda Inc. conducted a re-examination of core samples from holes located in the Dos Amigos target and provided an updated mineral reserves estimate of 20 million tons at approximately 0.7% copper.
Shell Chile Metals Division completed a detailed geological and alteration mapping of the Domeyko cluster, along with geochemical sampling, geophysical studies, and the execution of 5,772.50 meters of exploratory drilling in 29 holes. The work done by Shell resulted in the expansion of the Dos Amigos supergene resources to 5 million tons at 1.75% copper and 0.25 grams per ton of gold. Furthermore, Shell reported hypogene resources totaling 36 million tons at 0.36% copper and 0.26 grams per ton of gold, for the same area.
In 1985, the local venture ‘Compañía Minera San Esteban’ reinterpreted the supergene blanket and completed eight vertical exploratory holes, totaling 744.85 meters, with the goal of validating the grade and volume of the secondary mineralization. Indicated and measured reserves were reported for a total of 5.2 million tons at 1.44% copper and 0.31 grams per ton of gold, considering a cutoff grade of 0.5% copper.
In 1986, CEMIN Holding Minero acquired the property. Since 1996, the enrichment blanket at Dos Amigos has been open-pit mined by CEMIN. The extracted ore was processed using heap leaching and solvent extraction-electrowinning (SX/EW) methods at 10,000 tons per year plant, to produce copper cathode. The heap leach mining operation at Dos Amigos was discontinued in 2015 due to the depletion of secondary sulfide reserves.
During 2018 and 2019, CEMIN conducted additional geological mapping, geochemical rock sampling, and 11,018 meters of drilling, executing 140 holes. The primary aim was to identify new oxide and secondary sulfide copper resources to support the reopening of the Dos Amigos plant. During this period, two deep holes were drilled at the Dos Amigos orebody to assess the continuity of copper and gold mineralization at depth, reaching depths of 450.60 meters and 518.85 meters, respectively.
Between 2021 and 2023, the company completed a diamond-drilling program, involving seven holes, totaling 4,413 meters. Drilling results from 2018-2019 and 2021-2022 campaigns validated copper and gold grades within a quartz-diorite porphyry system, corroborating the continuity of hypogene sulfide mineralization to a depth of approximately 650 meters from drill collars.
In 2023, Andean Belt Resources acquired the mineral rights of the Domeyko Sulfuros project.
GEOLOGY AND MINERALIZATION
The local geology of the Domeyko Sulfuros project is characterized by andesitic volcanic rocks of the Punta del Cobre Formation (Tithonian-Early Albian), which are intruded by quartz-diorite porphyry stocks.
The volcanic package is composed by poorly stratified volcanic agglomerates and a set of lavas and volcanic breccias. The breccias have angular to subrounded fragments of up to 20 cm within a porphyritic andesite matrix. The andesites are dark gray in color and, when altered, they turn into white to light gray.
The volcanic sequence is intruded by bodies of quartz-diorite composition which are assigned to the Cordón Las Bandurrias Batholith. The central intrusive mapped as Quartz-Diorite Porphyry 1 (PQD1) is emplaced within the Punta del Cobre Formation volcanic rocks and represents the main mineralized intrusive with potassic alteration, characterized by potassic alteration. A Quartz-Diorite Porphyry (PQD2) surrounds the PQD1 and is strongly overprinted by advanced argillic alteration and leached. Finally, minor late bodies of dioritic composition intersect the whole system.
Potassic alteration predominates in the mineralized areas and can be classified in intense potassic alteration (K+) and less intense potassic alteration (K-). The most intense K-alteration (K+) zone is characterized by a marked tardi-magmatic event with biotite and magnetite veins and disseminated, in addition to an overprinting of M and EB type veinlets and early A and B type quartz veins. Chalcopyrite and occasional bornite mineralization characterize this alteration zone and it is the most important copper and gold concentrations found. Less intensive K-alteration (K-) zone shows the development of biotite and magnetite veinlets and disseminations. The occurrence of early quartz veinlets (A and B) is lower, and it already has an incipient to moderate destabilization of the existing ferromagnesian minerals, showing biotite and amphibole chloritization and partial hematitization above the magnetite. Sulfide mineralization consists of pyrite and low quantities of chalcopyrite, with lesser amounts of gold. Surrounding the potassic alteration, the deposit presents the classic zonation associated with a hydrothermal porphyry system, grading to a hydrolytic assemblage denominated QS, phyllic alteration, where quartz-sericite predominates; finally, advanced argillic alteration is recognized in the upper parts of the system.
The western margin of the project area is defined by a granodioritic plutonic complex, which serves as hard-boundary to the hydrothermal alteration and, consequently, to mineralization. The eastern side of the project is characterized by a volcanic sequence assigned to the Cerrillos Formation, composed of grayish pyroclastic breccias, andesites, and tuffs.
Within the project area, the main alteration zones exhibit a strong structural control aligned with a N15°W trend, encompassing the Dos Amigos, Tricolor, Maria Soledad, among others.
The Domeyko Sulfuros project is classified as a copper-gold (Cu-Au) porphyry system, peripherally associated with skarns, mantos and breccia pipes deposits.
The porphyry copper deposits and prospects situated in the Coastal Range between latitudes 26° and 31°S, such as Domeyko Sulfuros, constitute another sub-belt of the Cretaceous copper belt of northern Chile with U-Pb ages ranging from 108 to 88 Ma. The U-Pb zircon ages for the Dos Amigos porphyry are 106.1±3.5 and 104.0±3.5 Ma, while the nearby Tricolor porphyry has an age of 108.5±3.4 Ma, corresponding to the mid-late Cretaceous timeframe (Albian-Cenomanian).
An important characteristic of porphyry districts is that they do not form deposits in isolation but rather tend to occur in “clusters”. This has been observed in the case of the Domeyko Sulfuros property where various porphyry intrusions, including Dos Amigos, Maria Soledad, and Tricolor, are exposed along a ridge that rises to an elevation of approximately 1,250 meters at the Domeyko hill. The dimensions of this cluster span 6 kilometers in the NS direction and 1 to 1.5 kilometers in the EW direction.
In porphyry copper-gold (Cu-Au) deposits, secondary minerals may develop in supergene-enriched zones through the weathering of primary sulfides. These zones, characterized by significantly elevated copper grades, were observed at the Dos Amigos target and constituted the focal point of previous mining operation at the property.
Relevant drilling related with the exploration of the hypogene mineralization
Even though historical exploration conducted at the Domeyko Sulfuros property by various companies at Dos Amigos identified the shallow part of the primary sulfide mineralization, the most significant drilling focused on the exploration of hypogene Cu-Au mineralization dates back to 2018.
Three deep holes were drilled at the Dos Amigos (SDDK 18-034 and SDDK 18-039) and Tricolor (SDDK 18-035) orebodies to assess the continuity of copper and gold mineralization at depth.
Holes located at the Dos Amigos orebody intersected a quartz diorite porphyry, exhibiting argillic and potassic alteration, hydrothermal breccias, and diorite dikes. The intersected sulfide zone reveals the presence of both disseminated and fracture-filling mineralization, including chalcopyrite, bornite, pyrite, and magnetite. The hole located at the Tricolor target intersected quartz-diorite intrusive with potassic alteration and primary sulfide mineralization, as shown in the following table
Table 1: Summary of the most relevant drill intercepts from the 2018 – 2019 campaign
Between 2021 and 2022, the company completed a diamond-drilling program, involving seven holes, totaling 4,413 meters. Six holes were collared in the Dos Amigos pit and one hole was drilled in the Marisol breccia, located adjacent to the north of Dos Amigos. The completed holes allowed for the expansion of the mineralized zone and confirmed that the orebody remains open in various directions and to depth.
Table 2: Summary of the most significant drill intercepts from the 2021–2022 campaign
Drilling results from 2018-2019 and 2021-2022 campaigns validated copper and gold grades within a quartz-diorite porphyry system, corroborating the continuity of hypogene sulfide mineralization to a depth of approximately 650 meters from drill collars.
MAPS AND FIGURES
PHOTO GALLERY
