Navigator, Canabrava cut kimberlite at Kat

The first hole of the 2001 winter drilling program on the Kat project in the Attawapiskat region of northern Ontario has intersected kimberlite.

The Kat project forms part of the Severn joint venture, under which Navigator Exploration (NVR-V) and Canabrava Diamond (CNB-V) are exploring for diamonds in the James Bay Lowlands. Navigator can earn a half-interest in the Kat project from Canabrava by spending $1.75 million on exploration. The Vancouver-based junior has already spent $1 million, and further budgeted $1 million for 2001.

The 150-sq.-km project was staked following a review of regional airborne magnetic data. The geophysical program was focused on the area near the Attawapiskat cluster of 18 known kimberlites, 500 km northwest of Timmins. Navigator completed more than 47,000 line km of additional airborne magnetic surveys last fall and identified “numerous” targets. Some targets have been followed up with ground geophysics.

Drilling is planned for 10 targets, at least five of which are near the Victor pipe, the site of a large bulk-tonnage sampling program undertaken by De Beers Consolidated Mines (DBRSY-Q) in 2000. Robin Hopkins, vice-president of Navigator, tells The Northern Miner that the objective of the first round of drilling is to test a wide range of targets exhibiting different types of geophysical signatures.

The first hole was vertically drilled, cutting 47 metres of kimberlite before exiting the body at about 50 metres of depth. The kimberlite is covered by 3 metres of overburden. At the same site, a second inclined hole was drilled, which passed through the kimberlite body at a down-hole depth of 38 metres. The new discovery occurs less than 4 km from a mini-cluster of four kimberlite pipes, including the Victor pipe, first discovered by De Beers in 1988.

Last year, De Beers processed 6,518 tonnes of kimberlite collected from two surface pits (5,350 tonnes) and several large-diameter drill holes (1,168 tonnes) into the Victor body. Results are unknown, but De Beers has publicly stated that, in 1999, a 330-tonne mini-bulk sample yielded 107.9 carats of diamonds with a value of US$16,590. This implies a preliminary grade of 0.33 carat per tonne, a diamond value of US$154 per carat and a kimberlite value of US$50 per tonne.

Further sample material from Victor is being gathered this winter by large-diameter reverse-circulation drilling. More work is planned on up to five of the nearby pipes.

Victor is the largest body of the 18 previously known kimberlites, which occur in an area 90 km west of the First Nation coastal community of Attawapiskat. The area lies 350 km from the nearest road and, in the summer, is accessible only by helicopter. From December to March, a temporary winter road connects to Attawapiskat, where it joins another winter road to Moosonee, some 240 km to the south.

De Beers first discovered kimberlite boulders in 1987 along a 10-km stretch of the Attawapiskat River, while carrying out detailed stream-sediment sampling. An aeromagnetic geophysical survey followed, using both total magnetic field and vertical magnetic gradient measurements, to cover 2,900 sq. km of ground. Thirty-three targets were identified, with ground magnetic surveys defining 16 near-surface expressions and 15 deeply buried basement features. Modelling of the magnetic signatures suggest sizes ranging from 0.4 to 18 ha.

Drilling in 1988 and 1989 confirmed 16 kimberlite pipes. More than 100 kg of core from each of the 16 kimberlites were analyzed for microdiamonds, and all but one proved to be diamondiferous. De Beers drilled three of the 15 other anomalies modelled as basement features and encountered only limestone to a depth of 200 metres. Subsequently, in 1994, two additional small kimberlites were discovered by Spider Resources (SPQ-V), KWG Resources and Ashton Mining of Canada (ACA-T) at the northern end of the cluster.

The Victor kimberlite is a multi-phase body comprising one large North pipe and one smaller South pipe. The pipes coalesce at surface and comprise a total area of 16.7 ha. Victor North has been drilled to more than 300 metres of depth, whereas Victor South has been tested to shallower depths.

In a separate program under the Severn joint venture, Canabrava will spend $1.5 million this year exploring the Frontier project, which comprises the Ogaki and Caribou blocks of claims. The 12-sq.-km Ogaki claim block was staked to cover five magnetic anomalies, whereas the 50-sq.-km Caribou block was staked in a region that returned positive indicator minerals. The Caribou claims also cover 21 specific target areas.

Canabrava President Rory Moore says the company is flying postage-stamp, high-resolution surveys over “a bunch of targets,” with drilling planned for late winter/ early spring.

Navigator holds the right to earn a half-interest in the Frontier project by matching Canabrava’s 2001 expenditures by Dec. 31, 2003.