Junior
The project, part of an untested high-sulphidation epithermal system, is 114 km south of the town of Huancayo and 250 km southeast of Lima. It occurs on the western margin of the Calipuy Volcanics, which also host the Pierina deposit, held by
The agreement calls for Cardero to pay US$600,000 in cash, issue 600,000 shares and spend US$6.5 million on exploration — all over a 6-year period. To meet its obligations, the company has negotiated an arrangement with
Cori-Huarmi is in the Neogene volcanic belt of the Central Cordillera Orientale mountain range. Elevations range between 4,700 and 5,000 metres above sea level. The prospect is hosted in a 4-by-3.5-km felsic volcanic complex that is believed to be Late-Miocene in age. The complex is dominantly composed of flat-lying rhyolitic and rhyodacitic crystal and ash tuffs, which were deposited on a sequence of andesitic pyroclastics and flows.
The property hosts a concentration of several vuggy silica-alunite alteration zones in an area measuring 4 by 1 km. This area is enveloped by a larger halo of sericitic, argillic and propylitic alteration. Cardero reports that at least one later silicification event is evidenced by crosscutting sets of quartz veins and siliceous replacements along fractures. Siliceous hydrothermal breccias are also present and are suspected to post-date the main hydrothermal mineralizing event. Pyrite and native sulphur are abundant in the system, in addition to the dominant quartz, alunite and clay minerals.
The entire hydrothermal system is thought to be faulted along northwesterly and easterly trending structures.
In 1997, Minandex collected 1,319 chip samples from the main outcrops of vuggy silica alteration. A vertical sample taken from one of the largest outcrops, dubbed Susan, averaged 3.4 grams gold over 33.2 metres. Another sample taken from the same area returned 1.6 grams gold over 28 metres.
A channel sample taken from the Diana outcrop, 250 metres west of Susan, has returned 192.5 metres averaging 1.41 grams gold. Other sample intervals taken from these two outcrops ranged from 50 metres grading 1.41 grams gold to 9 metres averaging 21.17 grams.
According to an independent geological report of the property by Staargaard Geological, none of the samples can be used to arrive at true widths of mineralized zones since the geometry of the zones has not yet been clearly defined. Despite this, the report states, “substantially elevated levels of gold are present over significant widths in a variety of orientations.”
In 1995 and 1996, Minandex performed a regional satellite image analysis and selected various targets for reconnaissance prospecting. A large-scale mapping and sampling program led to the discovery of the Cori-Huarmi area. In 1997, Minandex performed channel and chip sampling, combined with smaller-scale geological mapping. At year-end, the company drilled three holes totalling 755 metres.
Two of the drill holes were collared at the base of the Susan target, and an additional hole was put down at the base of the Diana target, both of which locally form cliffs. Assay results returned only a few short intervals of weakly anomalous gold. Most of the intersections exhibited argillic alteration with only minor amounts of vuggy silica and alunite.
In 1998, Barrick signed a letter-of-intent with Minandex and performed a geological mapping and sampling program, as well as a large-scale CSAMT (controlled-source audio-frequency magnetotelluric) geophysical survey. Encouraged by the results, the major selected and prepared drill targets and advanced the property to the drill-ready stage. At that point, attempts to complete negotiations with Minandex beyond the initial stage broke down and Barrick withdrew.
The CSAMT survey is reported to have outlined a large resistivity anomaly measuring 2,000 by 700 metres in the valley southwest of the Susan and Diana outcrops.
Present interpretations suggest that a series of northwesterly trending faults could have down-faulted the original alteration zone to the point where the rocks northeast of the Susan and Diana outcrops may represent rocks that are stratigraphically higher than those to the southwest. If this is the case, then Minandex’s drill holes would have passed under uplifted rocks of flat-lying mineralization. More recent rock sampling in the down-faulted block has outlined an anomalous gold zone that measures 2,500 by 500 metres.
Cardero intends to carry out sampling and geological mapping near the CSAMT anomaly, to be followed by a 3,500-metre drill program.
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