Finding new mining frontiers in a country that has been scoured with modern exploration methods can be a daunting task, but joint-venture partners
Project operator and 60% partner Canadian Gold Hunter recently intersected high-grade gold while drilling the Hunt zone on the Assean Lake shear-hosted gold project in north-central Manitoba. The latest round of drilling included 4,237 metres and 25 holes. Nine holes totalling 2,476 metres were drilled on the Hunt zone, while the remaining 16 tested reconnaissance targets on the northern side of Assean Lake.
Three holes drilled on the Hunt zone have returned the best results to date: hole 147 intersected 16.83 grams gold per tonne over 1.95 metres; hole 151 cut 16.96 grams gold over 2.95 metres; and hole 155 cut 38.78 grams gold over 2.94 metres. Significant visible gold was noted in each of the intercepts.
In addition, a second high-grade zone, known as Hunt B, was intersected in hole 147, between 40 and 45 metres below, and north of, the Hunt zone proper. Only the upper part of the Hunt B zone was cut in hole 151, which was shut down too early. The Hunt B zone was also intersected in hole 155. Assays are pending for holes 158 and 161, which tested the western extent of the Hunt zone. The high-grade shoot remains open to the west and at depth. In addition, the newly discovered Hunt B zone adds a new dimension to the property, and follow-up drilling is planned for the summer.
Work in the Assean Lake region began in early 2000, when Rare Earth, the 40% partner, recognized the potential for gold and nickel mineralization in the region. The Assean claim block is 120 km northeast of Thompson, on the boundary between the Churchill and Superior geological provinces. The property is underlain by Proterozoic-aged rocks which are cut by a major, deep-seated structure known as the Assean Lake shear zone (ALSZ). This break, which is longer than 200 km, was found to be comparable to structural breaks associated with other gold-producing regions in the Canadian Shield.
As a result, Rare Earth acquired the property, which covers a 20 km extent of the ALSZ, and began exploring for large-scale, high-grade gold deposits. Shortly thereafter, International Curator, Canadian Gold Hunter’s predecessor company, became a partner. Together, the partners have spent $2.5 million on exploration, resulting in the discovery of 11 gold occurrences.
BIF and Blowfish
In addition to the Hunt zone, the partners discovered the BIF zone, which has a known strike length of 800 metres and values of up to 4.26 grams gold per tonne over 1.75 metres, and the Blowfish zone, where the highest value is 5.69 grams gold over 6.2 metres. With gold mineralization occurring over a large, contiguous area, Assean Lake is considered a significant gold prospect.
Prospectors began exploring the region in the 1930s. However, the abundance of thick clay cover hampered their efforts, so they were limited to working on the thin shoreline of the lake, where rock outcropped. Prospectors discovered several high-grade gold occurrences in the limited exposure of rock.
Later, with the introduction of geophysical exploration techniques, geologists were able to get their first look beneath the clay-covered areas beyond the lakeshore. Early geophysical instruments detected subtle changes in the earth’s magnetic field and increases in the conductivity as surveys passed over the buried rock. Iron-formations consist of magnetite, a magnetic iron mineral, or pyrrhotite, a sulphur-bearing iron mineral, which is less magnetic but conductive. Other detectable horizons are composed of the minerals graphite and pyrite, which are highly conductive but non-magnetic. Several conductive horizons were drilled, resulting in the discovery of silver-lead-zinc mineralization in the 1960s. The Tex deposit is the largest of these occurrences. In the 1980s, Homestake Mining conducted a modern airborne geophysical survey over the area, but, again, success was limited by the thick clay overburden.
Metal ion survey
The advent of a geochemical method capable of detecting mineralization buried beneath metres of clay overburden changed the situation. The Mobil Metal Ion (MMI) geochemical survey, developed in Australia, proved effective in penetrating through the thick overburden that covers mineralization and identifying targets that would be missed by traditional geochemical surveys. Metal ions are believed to migrate from a source or deposit at depth and concentrate in the overlying soil, and an MMI survey can reveal subtle but distinct anomalies over the buried mineralization.
An MMI survey was undertaken on the Assean Lake property, resulting in the discovery of several completely buried gold and base mineral occurrences. The Hunt zone was identified during drilling of a prominent gold MMI anomaly, which was along strike of a weakly mineralized shear zone. A higher-grade core of mineralization was revealed following step-out pattern drilling. The Hunt zone is the most significant gold occurrence known to exist on the property.
The discovery of the Hunt zone demonstrates Assean Lake’s potential for shear-hosted gold deposits of economic size and grade. The deposit is open at depth, and high-grade mineralization in a similar geological setting has been discovered 3.5 km along strike of the zone. Information gathered as a result of the discovery will assist geologists in determining drill targets with characteristics similar to those associated with the Hunt zone anomaly. Also, understanding the plunge direction and geometry of the mineralized structure may help geologists determine future drill targets.
Drilling has also uncovered anomalous nickel mineralization at Assean Lake. This is significant, as the property is within the northern extension of the famed Thompson nickel belt.
As a result of these successes, Rare Earth signed two agreements with the original vendor of the company’s current Assean Lake claim holdings to acquire both the Row-Lass and Wood claim blocks. These claims cover the eastern and western strike extent of the Assean Lake project’s core claim group, which is held by the joint venture. The claims cover 32.7 sq. km in 16 claims along the ALSZ and will be held entirely by Rare Earth Metals. The option agreements call for property expenditures of $1.25 million, the issuance of 400,000 shares, and property payments totalling $650,000 over five years. The company has also issued 70,000 stock options at 35 per share for five years.
— The author is a geologist and freelance writer based in Toronto.
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