Cornerstone Capital Resources Inc. announces the following project update for the Cascabel copper-gold porphyry joint venture exploration project in northern Ecuador, in which the Company has a 15% interest financed through to completion of a feasibility study.
- Recent geological mapping and geochemical generative work along with re-processing of geophysical datasets, reveals strong prospectivity for porphyry copper-gold mineralization at Aguiñaga prospect, Cascabel.
- Four high-priority porphyry centres now recognized within the Cascabel project, within a total of nine porphyry targets inferred to date.
References to figures, photographs and tables 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:
The Aguiñaga prospect lies along a prominent topographic high (1615m) around 3km south of the village of Rocafuerte and about 1.3km to the north-east of Alpala. The interpreted porphyry centre at Aguiñaga occurs at the confluence of a deep seated regional north-west trending structure with a major north-east trending lineament (Figure 1). This is the same structural regime that hosts porphyry centres at Alpala.
The Aguiñaga prospect is characterised by a 500m x 500m magnetic high surrounded by an annular magnetic-low halo. (Figure 2, Inset A). This geometry is consistent with a porphyry system characterized by a central magnetic high related to an intrusive centre and a magnetite-destructive halo caused by pyritic phyllic / argillic alteration, such as indicated by large porphyry deposits elsewhere, including Alumbrera, Chile and Batu Hijau, Indonesia.
The presence of a contiguous and very strong (>145 milliseconds) chargeability high with a central tapering root at Aguiñaga, is a signature that is consistent with sulphide-bearing, disseminated and/or stockwork style mineralization peripheral to and above a porphyry stock. (Figure 2, Inset B).
Completion of a 100m x 100m soil grid over the prospect, shows that the Aguiñaga target area is also characterized by a central soil copper anomaly, which is defined at the 300ppm level with dimensions of 350m x 400m, and contains a high of 1145 ppm or 0.11% copper (Figure 2, Inset C). The presence of coincident molybdenum, gold and copper / zinc in soil anomalies supports an inferred porphyry centre characterized by higher temperatures of mineralization.
The manganese depletion in soil samples flanking the central copper zone to the north and south-west are inferred to be related to intense late-stage hydrothermal alteration. The presence of elevated zinc in soil in this area of low manganese is a geochemical signature that is typical of the metal zonation around porphyry copper-gold deposits.
Reconnaissance field-work has located mineralized porphyritic diorite along the northern slope of Aguiñaga Hill, which returned assay results of 0.41% copper, and 0.29 g/t gold (sample 50987). The diorite outcrop lies above the chargeability high that flanks the Aguiñaga Hill and is described as "a porphyritic diorite containing quartz-pyrite-chalcopyrite quartz veins within a groundmass containing hornblende phenocrysts altered to a magnetite-biotite-chlorite alteration assemblage". This style of hydrothermal alteration is consistent with proximity to a porphyry centre.
Detailed, 1:500 scale, "Anaconda" style geological and structural mapping, infill soil-sampling and spectral analysis of soil to determine hydrothermal alteration assemblages are planned in the near future to bring the prospect to a drill-ready status. Other magnetic and geochemical anomalies at Chinambicito and America-Tandayama require further mapping and sampling to define drill targets.