Rainy River Heats Up Northwest Ontario Gold District

The Rainy River gold district in northwestern Ontario is heating up as companies stake ground and begin drilling around the flagship property held by Vancouver-based Rainy River Resources (RR-V, RRFFF-O), where three rigs continue to intersect solid gold grades over substantial widths.

At least two other Vancouver companies, Bayfield Ventures (BYV-V, BYVVF-O) and Skyharbour Resources (SYH-V, SYHBF-O), have announced spring drilling campaigns in the area, while Q-Gold Resources (QAU-V, QUAFF-O) from Arizona has staked 10.5 sq. km in Morley Twp., a few kilometres southwest of Rainy River’s property.

The excitement stems from Rainy River’s ongoing drill program, which continues to hit gold at the recently discovered ODM zone, west of the main 17 Zone in Richardson Twp. The first 15 holes drilled into ODM over a 100-metre strike length intersected a weighted average of 4.65 grams per tonne gold with an average true thickness of 24 metres.

Rainy River expects to release a new resource estimate for the property by the end of May. In 2004, previous property owner Nuinsco Resources (NWI-T, NWIFF-O) of Toronto announced a National Instrument 43-101-compliant resource for the 17 Zone, including indicated resources of 1.75 million tonnes averaging 1.56 grams gold per tonne and inferred resources of 11.03 million tonnes at 1.33 grams gold, with copper, zinc and silver byproducts.

“The original estimates were based on a 200-metre down-plunge extension,” says Rainy River president Nelson Baker. “We are now including mineralization down to 300 metres and we will certainly demonstrate that the grades are higher, the strike length is longer, and that there could well be a commercial deposit there.”

The resource estimate may also include the ODM zone, which will “bump up the grade considerably,” Baker says. ODM is within the same stratigraphic package as the 17 Zone, but has more silicification and visible gold.

Baker, a geological engineer by training with 40 years experience, suspects that ODM will not be the last — nor the best — zone the company discovers along the 3-km-long gold trend that runs east-west through the property. Though Rainy River has intersected seven new gold zones since acquiring the property two years ago, he estimates that only about 25% of the property’s exploration potential has been investigated.

The company is currently stepping out at 60-metre centres along the trend, a contact between pyroclastic rocks and felsic rocks, to find more gold zones not only to the west, but also to the east of the 17 Zone.

“We thought that the 17 Zone was weakening to the east, but then we drilled a series of holes sixty metres apart to test that particular horizon at 200-300 metres below surface,” Baker says. “We were pleasantly surprised to encounter another high-grade ore shoot to the east, with an extension going east of that.”

Till sampling clues

He attributes Rainy River’s high hit rate to clues uncovered by a systematic, 700-hole reverse-circulation (RC) program conducted by Nuinsco during the 1990s. The basal till samples from that drilling have guided Rainy River to the head of gold-in-till dispersal trains and provided the first real look at the underlying geology, allowing better drilling accuracy.

Without till sampling, the gold zones underneath the glacial till blanket may have remained undiscovered, since the clay-rich overburden obscures geophysical signals and there is virtually no outcrop on the property.

Mineralization was originally discovered in the late 1980s during a rotosonic drilling campaign carried out by geologists at the Ontario Geological Survey (OGS), who knew there was a greenstone belt lying underneath the overburden but had no evidence of its economic potential. Follow-up drilling by Nuinsco, directed by overburden expert Stu Averill, outlined a 6-sq.-km gold-in-bedrock anomaly with assays of up to 7 grams gold per tonne.

A new geological model for the area is also helping pinpoint targets. Although geologists originally believed they were seeing shear-hosted mineralization typical of gold deposits in the Archean greenstone belts of northern Ontario, bedrock chips from the till sampling identified a large area of gold-enriched felsic to intermediate volcaniclastic rocks with alteration minerals similar to those associated with volcanogenic massive sulphide (VMS) deposits. The edges of the anomalous area matched the limits of a collapsed caldera that contained the gold zones.

Further structural work indicated that the gold zones had a predictable plunge to them.

“Once we got comfortable with the angle of the plunge, we started plotting our holes and have since achieved considerable success,” Baker says.

Rainy River is now using the same model as Bousquet, a gold-rich VMS district in northwestern Quebec. Bousquet 1 contained reserves of 6.4 million tonnes grading 5.55 grams gold, while Bousquet 2 was much larger at 23.3 million tonnes grading 5.14 grams gold and 2.12 grams silver. Worldwide, these gold-VMS deposits range in size from small sulphide lenses of 2-10 million tonnes to giant-sized lenses and stockwork-stringer zones of more than 50 million tonnes containing over 300 tonnes gold (about 10 million oz.).

This summer, Rainy River will direct some of its $7- to $8-million budget to the Off Lake area, 20 km northeast along the same belt. Mapping and prospecting at Off Lake last summer revealed another volcanic centre just like the one in Richardson Twp. that has not been explored for VMS-type mineralization before, while till sampling uncovered some dispersal trains.

Other activity

Other companies hope to emulate Rainy River’s success by using a combination of geophysics and geochemistry to penetrate the thick layer of overburden.

About 800 metres to the southwest and along strike of the 17 Zone, Bayfield Ventures has identified two northeast-trending structures with magnetics, completed three infill RC holes around old Nuinsco holes, and is planning 3-4 diamond-drill holes to test conductive zones that could represent structures or sulphides.

Skyharbour recently completed its winter exploration program on its three properties to the west and southwest of the Rainy River claims. The program included magnetic and electromagnetic surveys as well as 35 RC drill holes. Results are pending, but will provide the basis for the first phase of a diamond-drill program this spring.

Joining the group is Q-Gold Resources, which has staked 65 claims 6.4 km south of the Rainy River property and just south of the Quetico fault. The Q-Gold property is underlain by a mix of volcanic sediments and felsic intrusives that host strong conductive anomalies discovered by previous geophysical surveys, and a gold-in-till anomaly outlined by the OGS.

Meanwhile, Rainy River is seeking a partner for continued work on its property and recently appointed accountant Dale Peniuk to the board. Peniuk has previous experience in corporate finance, including financings, due diligence on potential merger and acquisition opportunities, and divestiture transactions.

— The author is a freelance writer specializing in mining issues, and principal of Toronto-based GeoPen Communications (www.geopen.com).