The Hope Bay gold project in Nunavut represents one of the premier exploration projects in all of North America.
Partners
Utilizing up to seven drill rigs on surface and two rigs underground, this may be one of the largest exploration programs undertaken in Canada this year. The program is designed to expand on known resource areas and test the potential of several new showings.
“Our plan is to step-out from the high-grade resources at Boston and Doris, as well as evaluate the near-surface potential at Madrid,” says David Fennell, president of Hope Bay Gold. “We will also be testing the potential of several high-priority prospects that returned encouraging gold values from surface sampling during the 2000 field season, including Chicago, Domani and Kamik, as well as beginning the evaluation of previously less-well-explored prospects.” The program got under way in early February.
The Hope Bay gold belt is a typical Archean greenstone belt comparable to the Yellowknife, Kirkland Lake and Hemlo belts. It comprises mafic meta-volcanic (mainly meta-basalts) and meta-sedimentary rocks that are bound by Archean granite intrusives and gneisses. The package has been deformed during multiple events and is transected by major north-south-striking shear zones that appear to have a significant control over mineralization, particularly where major flexures are apparent and coincident with antiforms.
Miramar and Hope Bay Gold purchased the Hope Bay project from Australian-based BHP in late 1999 for US$18.5 million. BHP had spent about $85 million on the project between 1991 and 1996, outlining a resource of 4.3 million ounces in three separate deposits: Boston, Doris and Madrid. The decision to sell the project was made after BHP deemed gold a non-core asset and withdrew from the gold business worldwide.
Previous work at Hope Bay included extensive geologic, geochemical and geophysical surveys, 180,000 metres of surface and underground drilling, a 2,300-metre-long decline completed to 200 metres below surface at Boston, extensive cross-cutting, and 27,000 tonnes of bulk-sampling.
Last year, Miramar and Hope Bay Gold completed a 46,000-metre program of surface and underground drilling designed to upgrade a portion of the previously defined resource to the measured and indicated category, as well as evaluate other areas of potential.
The joint venture outlined 1.4 million oz. of measured and indicated resources in the Boston and Doris deposits, and 1.8 million oz. in the inferred resource category for all three deposits. The resource figures (3.2 million contained ounces) are substantially lower overall than those calculated by the previous owner (4.3 million contained ounces), reflecting more conservative measures, including:
– the capping of higher-grade assays;
– a higher cutoff grade;
– elimination of certain deeper drill holes with poor survey control; and
– tighter geological constraints applied to the model.
The resource base includes 1.9 million oz. of near-surface, high-grade resources averaging 16.9 grams gold per tonne. “This is an excellent base from which to continue defining high-grade resources at Hope Bay,” says Miramar President Anthony Walsh.
The biggest of the three gold deposits defined so far is the Boston deposit, which lies near the southern end of the belt, about 65 km south of tidewater. Boston was extensively tested by BHP with 231 surface holes and 182 underground holes. A 2,300-metre-long decline was used to develop the deposit on three levels and mine a 27,000-tonne bulk sample. The gold is free-milling, with a 95% recovery, using a combination of gravity and cyanidation.
Boston is a shear-hosted gold deposit occurring in mafic volcanics in contact with sediments. Gold is associated with pyritic sulphide mineralization that forms in clots in quartz-carbonate veins and as a halo in the wall rock around the veins. The deposit contains three main subparallel zones: B2, B3 and B4.
Most of the drilling completed at Boston during 2000 was focused on the B2 zone (144 holes totalling 14,591 metres), which has been traced 1,000 metres along strike and to a maximum depth of 700 metres below surface. The B2 zone itself comprises six near-vertical, en echelon lenses that are typically continuous for 50-100 metres of strike and 300 metres vertically.
The Boston deposit contains a measured and indicated resource of 1.33 million tonnes grading 15.2 grams, equivalent to 651,000 contained ounces. A further 2.6 million tonnes grading 10.9 grams, or 895,000 oz., is in the inferred category. About 74% of the total resource is concentrated in the B2 zone, where the measured and indicated stands at 1.25 million tonnes grading 15.5 grams, or 620,000 oz., including 550,000 oz. averaging a grade of 20.2 grams. This resource lies within 250 metres of surface and over a strike length of 450 metres. A further 1.6 million tonnes grading 10.3 grams, equal to 531,000 oz., is categorized as inferred.
This year’s drilling program will target the extension of the B2 high-grade chutes a further 100 metres deeper. In addition, surface drilling will be directed at delineating three possible new high-grade chutes discovered south of the resource area in the fall of 2000. The joint venture will also target the definition of potentially higher-grade areas in the B3 zone.
Doris
The Doris deposit sits at the northern end of the belt, just 6 km from tidewater. It differs from the Boston deposit in that it consists primarily of massive white quartz veins that have seen little post-emplacement shearing. It consists of a steeply dipping, 4-km-long quartz vein system in folded and metamorphosed pillow basalts. More than five parallel vein systems have been identified to date, the most significant being the Lakeshore and Central veins. These have been traced for several kilometres along strike, to depths of up to 400 metres below surface and across thicknesses of up to 30 metres.
Significant mineralization appears to be localized where other structural elements interact with the veins. Two principal areas of mineralization have been identified to date, Doris North and Doris Central, separated by a third prospective area, dubbed the Connector zone.
The joint venture drilled 91 holes totalling 12,000 metres at Doris North in 2000. The bulk of the mineralization is related to a near-surface anticlinal fold known as the Hinge zone and, to a lesser extent, in the fold limbs hosting the Lakeshore and Central veins. Doris North contains a measured and indicated resource of 710,000 tonnes grading 21.2 grams, equivalent to 483,000 oz., plus an inferred resource estimated at 957,000 tonnes grading 16.9 grams, or 520,000 oz.
Of particular importance, the Hinge zone contains a measured and indicated resource of 201,000 oz. grading 29 grams, plus an inferred resource of 94,000 oz. at a grade of 37 grams, which could form part of a potential open pit.
As part of the same vein system, the Doris Central zone occurs 1.2 km to the south under a shallow lake at the intersection of two structures. Miramar and Hope Bay completed a total of 44 holes in 10,000 metres of drilling last year. Indicated resources total 418,000 tonnes grading 14.9 grams, or 201,000 oz., with a further 59,000 oz. contained in an inferred 114,000 tonnes grading 16 grams.
This year’s drilling will focus on chasing additional high-grade ounces at Doris North by stepping out on the Hinge zone to the north and by testing the extension of the Central vein to depth. As well, the joint venture will follow-up on some widely spaced intercepts in the Connector zone, which suggest potential for structurally localized mineralization at about 100 metres below surface.
Madrid
The Madrid deposit, 8 km southwest of Doris, has seen little work under the joint venture. It is a lower-grade deposit, associated with what may be altered basaltic komatiites. Mineralization is related to carbonate alteration of mafic volcanics interlayered with sulphidic sediments. The Madrid deposit contains three main zones: Perrin, Matrim and Rand. Each exhibits shearing and brecciation, iron carbonate alteration, quartz veining and variable grade gold mineralization.
Indicated resources stand at 328,000 tonnes grading 7.3 grams, while inferred resources are calculated at 744,000 tonnes grading 9.3 grams, for a total of 300,000 contained ounces.
One of the higher priorities of the 2001 exploration program is stepout drilling around 2000 hole M92, which was drilled 250 metres west of the Madrid deposit and intersected 51.8 metres grading 6.9 grams from surface (including 11.4 metres of 21.4 grams). The structure that is believed to control this mineralization is thought to extend several hundred metres west of hole M92. In addition, based on an improved understanding of the geologic controls on mineralization, drilling is to be carried out south and east of Madrid in the Patch Lake area, where prior drilling by BHP indicated good potential for additional mineralization. One of BHP’s holes intersected 7.1 metres grading 18.2 grams.
“These first-phase work programs in 2001 provide excellent opportunities for the expansion of the high-grade gold resource at these three deposits,” states Walsh. “Positive results would warrant additional drilling in these areas in a phase-2 program, and could advance us toward a decision on a feasibility study.”
Preliminary studies suggest Hope Bay could produce in excess of 300,000 oz. gold per year at cash costs of under US$200 per oz., with capital costs in the order of US$100-150 million.
Forty targets
A significant portion of this year’s work program will be focused on the discovery of potential new deposits on the 80-km-long Hope Bay greenstone belt. Previous work identified more than 40 targets.
“There is no shortage of opportunities for the discovery of new deposits on the Hope Bay belt,” says Fennell. “In fact, we have an overabundance of targets, which makes prioritizing where to spend our funds a challenge.”
Multi-hole RC drilling programs are scheduled for the Chicago, Domani and Kamik areas, to follow-up on results from 2000 surface sampling. The Chicago area shows potential for volcanogenic-massive-sulphide-related gold-silver mineralization, where surface sampling returned gold values ranging up to 45 grams and high silver values of 3,000-6,000 grams.
Domani and Kamik are Boston-style, high-grade, shear-hosted targets. Domani is the southern continuation of the shear structure hosting the Boston deposit. Surface sampling yielded anomalous values along 2.6 km of strike, with rock grab samples ranging up to 180 grams gold. Kamik is a prospect, where rock sampling of a 210-metre section of a 4-km-long zone of iron carbonate-altered shear returned encouraging gold numbers, ranging up to 248 grams.
RC drilling will also test the blind Miksa target, where the shears that host the Boston and Domani mineralization converge. The geological setting is prospective for near-surface gold mineralization. Other drill targets include Amarok 5 and North Patch. Regional exploration will be continuing along the belt.
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