Ten minutes, maybe 15. That’s about the time it took for prospectors Albert Chislett and Chris Verbiski to realize they had made a potentially significant mineral discovery while examining a prominent gossan on the northwestern side of Voisey Bay, some 35 km southwest of the Inuit community of Nain.
“We broke some fresh rock and could see the stringers of chalcopyrite shooting through the gabbro and knew we had about 1-2% copper over an area 500 metres long and between 40 and 80 metres wide,” Chislett told The Northern Miner during a recent visit to the discovery outcrop on the Voisey Bay nickel-copper-cobalt project owned by Diamond Fields Resources (TSE).
That discovery, made in September, 1993, by Archean Resources, was heady stuff for its founders, two struggling prospectors from St. John’s, Nfld., who at that time were grubstaked by Diamond Fields to look for diamonds, as well as gold and base metals. “We sat on that hill and started envisioning what it was going to look like in 10 years, with a mine and roads,” Verbiski said.
During the next few months, Chislett and Verbiski researched government literature and maps with a view to assemble a land package of favorable geology, similar to the discovery area, for staking.
This research showed that during the period 1985-1987, the Geological Survey of the Newfoundland Department of Natural Resources had carried out a mapping program in a 60-km corridor from Voisey Bay to the Quebec border. This work improved the existing geological data base of the region, especially of the Nain Plutonic Suite (1350 to 1290 Ma), which is situated near the 1800-Ma collisional boundary between the Archean Nain province and the Paleoproterozoic Churchill province.
During this period, a previously unrecognized layered and massive troctolitic mafic intrusion was noted north of Voisey Bay, and was named the Reid Brook Intrusion. Also highlighted was a gossan zone, described as being hosted by a troctolitic dyke of the Reid Brook intrusion.
As a result of their research, Chislett and Verbiski learned that their “discovery” had been previously mapped by government geologist Bruce Ryan as a pyritic gossan. The fact that no anomalous metal concentrations were detected at that time no doubt reflects the leaching of metals from the deeply weathered surficial cap. The prospectors also correctly mapped the local geology as having an easterly strike, rather than a northerly one as shown on the government map.
“At first we looked at a volcanogenic massive sulphide model,” Chislett recalls. “But there was no lead or zinc, no hydrothermal activity, and no alteration, so we soon started looking (for answers) to the Sudbury and Thompson nickel camps.”
By January, 1994, the first staking effort had begun. The goal was to cover known mineral occurrences in similar-aged rock types, as well as other layered intrusive complexes or the root zones and fragments of eroded layered intrusions within the Nain Plutonic Suite, the lithostratigraphic host to the Voisey Bay mineralization.
By the time the discovery holes were announced, a staking rush was well under way in Labrador. By this point, the Diamond Fields-Archean land package had been expanded to cover a large area surrounding the Reid Brook intrusion, as well as other troctolitic intrusions of the Nain Plutonic Suite. The land package, which covers 1,800 sq. km, includes the two largest of these intrusions, Kiglapait and Newark Island. These targets are considered to have good exploration potential because of the presence of numerous sulphide showings.
In the early days, Chislett and Verbiski admit they had a tough time selling the project to Diamond Fields. “They were not that excited at first and gave us a shoestring budget of only $175,000 for 1994. We went over budget, but I think they forgive us for that.”
The prospectors went on to spot the first four discovery holes of the winter drill program at Voisey Bay. The rest, as they say, is history still in the making. Archean has a 3% net smelter royalty on the project, and Chislett and Verbiski have so far resisted the temptation to sell this for “many millions of dollars.” (They were recently granted options to buy 175,000 Diamond Fields shares at $16.99 each until Feb. 26, 1997.)
Meanwhile, a host of competing majors and juniors have scrambled to pick up ground surrounding the Voisey Bay discovery. This was expanded to include other targets, such as the Harp Lake intrusive south of Voisey Bay which had been prospected by Kenneco in the 1970s and later by others.
Much of the recent staking activity was focused on Nain province, the western remnant of a once extensive Archean terrane known as the North Atlantic Craton which was fragmented by continental drift around 100 Ma ago. Other parts of this craton today are situated in Greenland and northern Europe, and they contain rocks identical to those in Labrador.
“We weren’t surprised to hear that Cominco has staked Voisey-Bay-type targets in Greenland,” Chislett said.
Even though the main Voisey Bay deposit (within the ovoid) is well-defined, Chislett and Verbiski still see plenty of potential for new discoveries on the Diamond Fields land package. Sulphide showings have been identified, and Chislett said all contain nickel values. Some are in areas near the Voisey Bay target, and others are in areas clearly not related to that discovery.
“We have many targets that we intend to follow up when the snow is off the ground,” Chislett says. “The geophysics look good, but I don’t get excited until I see what’s in the ground.”
Chislett also hinted that he and partner Verbiski will keep an eye out for other types of deposits within the Diamond Fields land package, such as gold, base metals and platinum group elements.
Labrador is best known for its iron ore deposits (within the Labrador Trough and extending into neighboring Quebec), but it is considered prospective for other types of deposits. The region is underexplored because, for many decades, large tracts of ground were held under concession to only a few players which were under no obligation to carry out serious work. This policy was scrapped in the 1970s, in favor of the same tenure system that now exists in the rest of Canada.
Labrador hosts a specialty minerals deposit (Strange Lake, which contains yttrium, zirconium, beryllium, niobium and rare earths), and similar types of deposits are also known to occur in “neighboring” Greenland. Several uranium deposits have been found in Labrador, and the region is considered prospective for platinum-group-elements, in either layered intrusions or in association with nickel-sulphide deposits in ultramafic rocks.
And who knows, the exploration activity taking place in Labrador may yet lead to the discovery of diamonds.
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