Yamana, Noranda explore Fin del Mundo project

As the search for base metals becomes more and more difficult, many Canadian exploration companies are venturing farther and farther abroad.

Exemplifying this trend are Yamana Resources (TSE) and Noranda (TSE), which are jointly exploring the Fin del Mundo polymetallic property in the Argentine province of Tierra del Fuego.

Recently, The Northern Miner, along with senior management of Yamana, visited Fin del Mundo, which lies about 10 km north of Ushuaia. With a population of about 40,000, Ushuaia is the provincial capital, as well as the world’s most southerly city, at a latitude of 54 south.

The location may sound isolated, but the property is crossed by a major national highway, and port facilities are capable of handling ocean-going freighters. The city is also serviced with daily flights from Buenos Aires.

Encompassing more than 140,000 hectares, the property is underlain by a 45-km-long section of the east-west-trending Rio Encajonada mineral belt. The belt is composed of alternating felsic and andesite volcanics within a predominately sedimentary sequence. Farther to the north, the stratigraphy is repeated as a result of thrust faulting.

The property first received attention in the 1970s when St. Joe Minerals conducted stream-sediment sampling and delineated several copper, zinc and lead anomalies.

Later in 1994, Yamana acquired the property and traced one of the stream-sediment anomalies to a mineralized, gossan-capped outcrop in a hanging valley at an elevation of 700 metres above sea level.

Chip samples taken across the 210-metre-long, massive sulphide lens averaged 1.45% copper, 1.64% lead and 7.13% zinc, as well as 0.21 grams gold and 48.4 grams silver per tonne. Other high-grade samples reportedly averaged more than 20% combined base metals.

Luckily for Yamana, the Arroyo Rojo showing had been hidden from view and only recently became visible, at the base of a receding glacier.

Noranda became aware of the project and, in 1994, signed a joint-venture agreement with Yamana. The major can earn a 50% working interest by spending $5 million on exploration by Dec. 31, 1998. Should it choose to do so, Noranda can increase its interest to 60% by generating a feasibility study for the project by the year 2002.

During The Northern Miner’s visit to Fin del Mundo, field work was just winding down and data were being compiled. Despite the shorter-than-usual field season (resulting from the timing of the agreement), much work had been accomplished.

Yamana constructed a 10-line-km grid covering the Arroyo Rojo showing and carried out mapping, sampling and geophysical surveys. In addition, other channel samples were taken over the showing, and these returned values comparable to previous chip samples. Property-scale mapping and sampling indicate the favorable horizon has a strike length exceeding 18 km.

Geologists believe the Arroyo Rojo represents a typically Kuroko-style, volcanogenic, massive sulphide deposit. The mineralization is enclosed within a zone of chlorite alteration, with a core of strong sericitic alteration. Host rocks tend to be depleted in sodium and enriched in potassium.

Yamana collected more than 700 stream-sediment samples, and results have so far led to the identification of another three base-metal, stream-sediment anomalies. In addition to the stream-sediment sampling, regional mapping indicates the horizon may extend another 50 km beyond the scope of the detailed survey.

The partners are considering carrying out an airborne geophysical survey, which would help define targets warranting further investigation. If all goes well, drilling of the Arroyo Rojo showing, and of the other showings, will be carried out in early 1996.