CYU has several exploration project interests in Chile. These comprise Humitos, Palmani and Sulfato and the location of these projects are shown below:
Humitos
The Humitos Copper Porphyry property is in the Copiapo District of northern Chile. Humitos consists of a number of undrilled targets including an untested supergene horizon in the most prolific copper belt in the world, the Chilean Cordillera. 10km north is the project Inca de Oro (400Mt @ 0.6% Copper) owned by Codelco and subject to a purchase agreement with Pan Aust Ltd.
Figure 1. The Humito project is a copper porphyry project 90km north of Copiapo, approximately 10km to the south of the village of Inca de Oro, an historic mining centre. Tenure comprises 17 tenements for a total area of 4,500ha. The project is a comfortable 1500-2,600m above sea level.
Humito is in the centre of a broad NNE-trending structural corridor bounded by the Atacama Fault to the east and the Domeyko Fault system to the west. This zone separates the Coastal and Pre-Andean mountain ranges and hosts a number of important deposits including the El Salvador, Damiana and Caballo Muerto deposits in addition to copper silver epithermal vein mineralisation of the Inca de Oro district.
Figure 2. Old Kennecott RC hole in advanced argillic alteration on the northwest side of Cerro Humito. The advanced argillic alteration can be seen higher up the slope below the dark bluffs of massive vuggy silica.
At Cerro Humito hydrothermal alteration occupies a discontinuous zone of 10x2km extent characterised by a massive vuggy silica core centred over Cerro Humito surrounded by intense quartz sericite alteration. In addition to the intense pyrite mineralisation associated with the quartz sericite alteration, relict chalcopyrite has been noted in petrographic samples taken from limited previous drilling. The geometry of the alteration assemblage together with what appears to be a central silica cap is indicative of an intact porphyry hydrothermal system preserved at depth. Previous Exploration In 1987 Kennecott carried out a program of induced polarisation and drilled nine reverse circulation drill holes ranging 150-244 metres depth. The work was centred on the area around Cerro Humito. Maximum assays of 1400ppm copper and 2200ppm molybdenum were returned in an area interpreted to overlie a potential supergene blanket at depth. Rey initiated preliminary reconnaissance of the prospect. This review included collection of samples from five drill holes around Cerro Humito for mineral analysis. Results indicated that Humito represented an intact porphyry system, preserved with a barren cap and minimal erosion. Sulphides are dominated by pyrite (iron sulphide) with an increase in chalcopyrite (copper sulphide) towards the centre of the system.
Figure 3. Section from previous exploration indicating the sulphide halo of the system has been tested but not the central core.
Economic Potential The Humito prospect is a classic example of a well preserved high level porphyry system displaying normal porphyry alteration patterns including a silica cap. There is potential for a secondary zone of copper enrichment at depth. The large alteration system, occupying approximately 20km2, has only been tested with nine shallow RC holes around the Cerro Humito area and is effectively untested. The project lies within a metallogenic belt of demonstrated prospectivity. In 2006 Codelco defined a large porphyry system of 400Mt grading 0.6% combined copper and gold, at Inca de Oro, 12km north of Humito.
Sulfato
China Yunnan Copper Australia Chile Limitada, a Chilean subsidiary of CYU, has signed a farm-in agreement with Compañía Contractual Minera Los Andes (a subsidiary of Codelco, the world’s largest copper producer) (CCMLA), for the copper porphyry exploration property Sulfatos in northern Chile. CCMLA worked at the project for more than 10 years and defined a porphyry system through mapping, geochemical sampling and drilling. The drilling highlight from these previous activities was drilling that intersected 92m @ 0.65% Cu, open along strike and at depth.
In April 2013 CYU undertook a PDIP-MT geophysical survey at Sulfato to identify areas of elevated chargeability and conductivity. No prospect-scale geophysics had previously been conducted at Sulfato and the planned drillholes took account of priority target areas identified by the CYU geophysics.
A total of four proposed drillholes were designed for the formal exploration program, three in the untested western-most area of the prospect, and one in the partially explored eastern area. (The figure below shows the location of the two completed drillhole locations).
The first completed drillhole, SFD-003, was collared in sediments and intercepted a small hydrothermal breccia and ensuing porphyry intrusive from 78 metres depth. Despite the encouraging alteration styles early in the drill hole and the presence of a porphyry intrusive, no significant copper mineralisation was intersected. The source of the strong conductor is potentially the significant pyrite veining intersected in the drillhole. The drill core samples from this hole will not be assayed at the present time.
The second drillhole, SFD-004, was located in the eastern area of the project and was drilled to a depth of 510m. It was designed to target an untested intrusive on the south-eastern side of the valley, which coincided with a chargeability and deep-seated conductivity anomaly. Drillhole SFD-004 showed more encouragement than the first drillhole as a wide intrusive was intersected from 241.6m, and quartz-pyrite veins were common with frequent traces of chalcopyrite from 60m depth. The drill core samples taken from this second hole will be fully assayed and CYU expects results from the laboratory by early 2014. At that time a decision will be made about further funding on this project.
Palmani
The Palmani project is located in the porphyry copper belt of northern Chile in the Arica Province, Arica–Parinacota Region (Region XV) approximately 56km northeast from the regional centre Arica.
CYU completed a deep-penetrating 3D IP geophysical survey on this project during 2013.
The geology at Palmani is of interest due to the notable occurrence of porphyry-style lithologies and alteration types. The system appears to be large, with porphyry style alteration also noted in the adjacent valley at La Mancha (not a CYU project). As shown in the figure below, the Palmani project is situated in rugged mountainous terrain.
The geophysical survey provided information regarding the cover sequences and basement rocks. The depths to the base of the cover sequences have been modelled to at least 800m. Some potential anomalies have been seen, including a chargeability anomaly in Line 1, and two resistivity anomalies in Line 2 (see the figure below). Any testing of these targets would require significant drill holes, of at least 1km depth, in order to penetrate into basement rock.
The exploration target at Palmani is a high grade supergene enrichment zone, which will undoubtedly need to find significant grades exceeding 1% copper in order to establish a commercial resource. Based on the results of the CYU geophysical survey, the anticipated cost for an exploration program at Palmani will most likely be a minimum of $1.5 million, and would include a considerable access track and at least one or two deep diamond core holes. CYU management is currently reviewing the results of the geophysical survey and the best means of sourcing funds to carry out such an expensive initial exploration program.
