Cornerstone Capital Resources Inc. announces the following project update for the Company's Cascabel copper-gold porphyry joint venture exploration project in northern Ecuador.
- Drill hole CSD-14-008 ("Hole 8") was completed at 1310.45m on October 11
- Hole 8 intersected visible copper sulphide from 367.10m to 680.80m and from 902.78m to 1310.45m, a collective length of over 720m
- Hole CSD-14-009 ("Hole 9") expected to commence in November
- Orion IP survey completed at both Alpala and Aguinaga targets
- Final stages of processing for Orion 3D "Deep Earth Imaging" IP geophysical data underway
- Geological model for porphyry copper-gold mineralization further refined
- Expert consultant to be engaged soon to manage metallurgical testwork
- Rio Cachaco soil sampling program ongoing
All reported intervals referred to in this news release are core lengths. At present the true thicknesses are uncertain due to the early stage of drilling.
References to figures and photographs related to the version of this release on the Company's website (www.cornerstoneresources.com) or visible in PDF format by clicking the link below:
Hole 8 on the Cascabel concession was drilled at the Alpala porphyry copper-gold prospect (Figure 1). The hole was sited from the same collar as Hole 5 and drilled towards grid north at a dip of 85 degrees. Hole 8 was sited to test for northeast extension of the high-grade mineralization that has been discovered extending along a northwest trend from Hole 5 to Hole 7.
Hole 8 was terminated on October 11, at a depth of 1310.45m. Extensive intersections of visual copper sulphides were observed from 367.10m to 680.80m and from 902.78m to 1310.45m at end of hole. Significant lengths of strong copper sulphide mineralization were observed in the deeper interval.
These results reveal continuity of mineralization extending northeast-ward off the Alpala Footwall Structure. Plate 1-3 illustrate the style of mineralization encountered in Hole 8.
Hole 9 is located 120m north of the Hole 5 drill pad and is being drilled with an 85 degree inclination towards 210 degrees UTM (Universal Transverse Mercator). Drilling is scheduled to commence in November.
The hole is sited primarily to test the depth extension of the high-grade copper and gold mineralization encountered in Hole 5 (688m at 0,92% Cu and 0.90 g/t Au, including 258m at 1.27%Cu and 1.40 g/t Au). By extending the high grade copper and gold mineralization intersected in Hole 5 to 1700m depth in Hole 9, this would deliver a high grade interval at Central Alpala of over 1000 vertical metres.
The geometry of high-grade mineralization defined to date appears to be controlled by quartz diorite and tonalitic intrusions that have intruded up along a northwest-southeast trending fault zone (the Alpala Footwall Structure; Figures 5 and 6). The lateral width of mineralization in the northeast direction was tested with Hole 8. Hole 9 is sited to better test the vertical extent of mineralization that appears to be controlled by the Alpala Footwall Structure. The zone of porphyry copper-gold mineralization and its intrusive source is expected to widen gradually with depth, and high-grade mineralization is anticipated to extend to substantially greater depth than encountered in Hole 5 which was terminated after drilling through the southwest side of the Alpala Footwall Structure.
At the significant depths that the Alpala prospect is being drill tested, an extensive vertical interval of mineralization is one of several important factors to sustain a block cave mining operation. Hole 9 will assist in defining the vertical extent of mineralization by testing several hundred metres below and north of the high grade intersection in Hole 5, and east of the high grade intersection in Hole 7.
Following the completion of Hole 9, Holes 3 and 5-9 will have sufficiently constrained the geometry and controls on mineralization to optimize drill testing for extensions of mineralization laterally along the Alpala Footwall Structure, and of robust targets that lie northwest and southeast of Central Alpala.
Orion 3D IP Survey
The Orion 3D IP survey on the Alpala grid (9.8 km2) commenced on August 3, and the survey on the Aguinaga grid was completed during the 1st week of September.
Detailed processing of the data is currently being conducted by Quantec technicians in Toronto, in consultation with consultant geophysicist Chris Moore. Final processing of chargeability and conductivity-resistivity datasets is in progress. Relatively advanced models of the data are available for the company to work with.
Selected views of the preliminary inversion models are illustrated in Figures 2 to 6. Key aspects of the preliminary IP data are listed below.
- The magnetotelluric (MT) conductivity data reveal a deep conductive body that extends from below 2 kilometres depth and merges up into the base of the MVI modelled magnetic body at North West Alpala (Figures 2, 3, 4). The MT conductor is interpreted to be a magnetic and sulphide-bearing intrusion which is slightly more conductive than the surrounding sequence.
- Drilling along the margins and through the MVI magnetic anomaly (Holes 5, 7 and 8) reveal it is associated with significant quantities of secondary magnetite in inner propylitic and transitional potassic alteration zones that is associated with porphyry style copper-gold mineralization.
- The deep MT conductor (900-2000m depth) is better imaged at shallower levels (0-900m depth) by the shallower DC conductivity dataset. The conductive bodies in this shallower zone (e.g. C1 and C2; Figures 2 and 5) lie mostly within the clay-altered lithocap above the MVI magnetic anomaly which maps the magnetic porphyry system and its magnetic margins at Central and Northwest Alpala.
- The close spatial association of the deep MT conductor that envelopes the root of the MVI magnetic anomaly at Northwest Alpala, and the location of strong DC conductors in the lithocap directly above the MVI magnetic anomaly, suggest that the main locus of the Alpala porphyry system is closely associated with the MVI magnetic anomaly.
- The IP data supports the high prospectivity of the MVI magnetic anomaly, and particularly where it penetrates the MT conductivity anomaly at Northwest Alpala. The prospectivity of Northwest Alpala is strongly supported also by surface spectral data that identify acidic alteration assemblages within the clay-altered lithocap above the MT and MVI anomalies.
- The IP data is supporting and refining an additional high quality target at Southeast Alpala, where coincident clusters of chargeability and conductivity anomalies overlie a deep magnetic anomaly (Figures 5 and 6). The prospectivity of the region was initially identified in surficial spectral datasets that mapped highly acidic clay assemblages within the lithocap over the South East Alpala target area.
- The Southeast Alpala target is shallower than the Central and Northwest Alpala target, being at around 600m depth to the top of the magnetic body that underlies the chargeability and conductivity responses.
- The convergence of the magnetic data, the IP data and the geology model allow us to view Central Alpala and Northwest Alpala as parts of a larger coherent target area. The Southeast Alpala target area (1km by 200-500m) covers a similar area as the Central and Northwest Alpala combined target areas (1.1km by 200-500m).
Both the Central/Northwest Alpala target and the Southeast Alpala target extend northeast-ward off the Alpala Footwall Structure in a 'tear-drop' geometry (Figures 5 and 6). The similar relationship between the two principal targets and the Alpala Footwall Structure suggest that it is a key structural conduit for potentially more than one porphyry system at Alpala.
Following the independent review of geological data from the Alpala prospect by Dr. Steven Garwin and collaboration with the joint venture (ENSA)'s technical team, a robust geological model has been developed for the area of drilling at Central Alpala.
With the completion of Holes 1 to 7 at Central Alpala, sufficient geological data from drill holes was available to plot surfaces (shells) on several geological features within the area of drilling at central Alpala. The surfaces created for the area of drilling utilized all the drill hole data available at the time and data from the surface trenches. The following surfaces were created:
- Two phases of diorite intrusions.
- The northwest-trending Alpala Footwall Structure.
- A surface defining porphyry B-veins at densities > 0.5%.
- A surface defining chalcopyrite/pyrite (Cp/Py) ratio of >1 and >0.5.
- A surface defining copper (Cu) at >0.3%.
- A surface defining molybdenum (Mo) at >10ppm.
- A surface defined by the Al2O3/Na2O ratio which approximately maps the lithocap base.
Porphyry copper-gold deposits typically exhibit increasing 'B-vein' abundances, Cp/Py ratios, plus increasing Cu and Mo contents as the deposit is approached from the external country rock to the internal intrusions that host much of the mineralization. The geometries of these shells aid in establishing vectors towards the higher grade parts of the deposit. Dr. Steven Garwin showed that many of these types of shells envelope the porphyry mineralizing centre in a consistent pattern, and from which vectors towards mineralization can be established.
Figure 7 shows the geological model at Central Alpala. In porphyry systems, the geometry of these shells grossly reflects the geometry of the causative mineralizing intrusion - equidimensional dome-like intrusions have equidimensional dome-like carapaces of B-vein shells, while tabular and finger-like intrusions have tabular and finger-like enveloping shells of B-veins. The B-vein generation of quartz veins host much of the copper and gold in porphyry deposits. The geometry that is taking shape at Alpala is of a tabular and elongate mineralized body, striking northwest-southeast, and dipping steeply towards the northeast. Many of the shells shown in Figure 7 yield a tabular geometry that gradually widens with depth. This geometry suggests that the mineralizing intrusions are tabular (dyke-like) and have penetrated up along a major northwest-southeast trending fault structure, either defined by or associated with the Alpala Footwall Structure.
Dr. Garwin has recently also been engaged to train the ENSA technical team on site in geological mapping techniques that facilitate the methodology of establishing vectors towards the centre of the mineralizing system. Geological mapping is presently underway within and around the edges of the lithocap at Alpala. This work will provide further geological information to supplement the extensive geochemical, spectral, magnetic, electrical IP and geological datasets that exist at Alpala and across the Cascabel project.