Six years of regional reconnaissance exploration by
With microdiamond results pending for the four new Renard discoveries, Ashton has reported encouraging results from a small mini-bulk sample designed to test the potential of the Renard 2 kimberlitic body for commercial-size stones. A 2.4-tonne sample collected in March from four core holes, each 4.8 cm in diameter, yielded a 1.69-carat parcel of diamonds larger than a 0.8-mm bottom-size cutoff, for an implied grade of 0.693 carat per tonne (or 69.3 carats per 100 tonnes). The five largest diamonds recovered range in size from 0.1 to 0.16 carat and include both single and composite crystals. Two of the stones are colourless; the three others are pale yellow or pale brown.
The mini-test sample was composed of mainly kimberlitic breccia, and several included intervals of hypabyssal facies kimberlite and country rock.
Renard 2 has a geophysical signature at surface measuring about 150 metres long and 100 metres wide. Based on the six holes completed to date, the kimberlitic body is interpreted to be 65 metres wide at a vertical depth of 80 metres. A vertical hole, collared in the centre of the geophysical anomaly, was shut down in kimberlitic breccia at a depth of 225 metres. Renard 2 is overlain by about 20 metres of overburden.
Renard 2 was discovered 1 km south of the diamondiferous Renard 1. Brooke Clements, Ashton’s vice-president of exploration, previously described the Renard 2 kimberlitic body as a xenolith-rich autolithic breccia, with local variations of xenolith and olivine macrocrysts. A minor amount of hypabyssal kimberlitic material was present in the discovery holes. In total, 116 micros and 29 macros were recovered from 163.1 kg of discovery core sample, including five stones greater than 0.5 mm in two dimensions. (A macro here is defined as exceeding 0.5 mm in one dimension.)
Encouraged by the results so far from Renard 2, the joint venture is planning to collect a larger sample and conduct additional delineation drilling. Details of the next stage will be announced over the coming 6-8 weeks.
Ashton and Soquem, a Quebec Crown corporation, are 50-50 partners in a joint venture that holds 3,800 sq. km of mineral permits in north-central Quebec. The permits are broadly held in two areas: the Otish Mountains, 275 km northeast of Chibougamau, and the Caniapiscau region, 500 km east-northeast of Radisson. More recently, the joint venture acquired the Taiga property, north of the Otish region.
In the fall of 2000, Ashton and Soquem acquired their first exploration permits in the Otish and Caniapiscau regions, and these cover several “significant” indicator mineral dispersion trains detected by reconnaissance programs. Samples containing more than 1,000 indicator minerals were collected in some of these areas. Ashton was particularly encouraged by the high percentage of G10 pyrope garnets recovered in some of the samples from the Otish Mountains.
The joint venture had quietly been conducting regional heavy-mineral sampling in northern Quebec since 1996. More than 1,700 samples were initially collected across an area measuring 425,000 sq. km, for an approximate density of one sample per 250 sq. km. The dominant medium sampled was eskers. Any anomalous kicks were followed up with a more detailed grid pattern of sampling.
The joint venture’s current holdings in the Otish Mountains area are subdivided into Foxtrot, a large claim block covering 1,536 sq. km in the north, and Tichegami, which covers a scattering of claims totalling 1,040 sq. km in the southern region. Ashton flew magnetic geophysical surveys over the core of the Foxtrot property in late 2000 and followed this with ground geophysics over eight specific targets in March 2001. That summer, more than 350 till samples were collected to define the drill targets. In addition, fields crews found a fist-size piece of altered ultramafic “kimberlitic” float 400 metres down-ice from the Renard 1 target.
In September 2001, four targets were drill-tested on the Foxtrot property, resulting in the discovery of the Renard 1 and 2 kimberlitic bodies. Owing to budgetary constraints, the holes were limited to 100 metres of depth. The Renard 1 body yielded 54 micros and 5 macros from 205.8 kg of tested core. One of the stones exceeded 0.5 mm in two dimensions.
Convinced there were additional kimberlitic bodies to be discovered, Ashton conducted ground geophysical surveys over some 10 airborne magnetic targets in the anomalous indicator mineral areas. The drilling of four geophysical targets in March and early April resulted in the discovery of four new kimberlitic bodies, clustered within 1 km of the Renard 2 body.
A helicopter-borne magnetic and electromagnetic survey over the Foxtrot property will kick-start an ambitious summer’s program of reconnaissance work and heavy-mineral sampling. Microdiamond results from the four new Renard discoveries will determine the timing of summer drilling programs.
Ashton sparked an unprecedented staking rush in Quebec late last year after confirming that its first two kimberlitic discoveries were diamond-bearing. Since Quebec allows for map-staking, several junior companies positioned themselves using the Internet and a credit card.
Ahead of pack
This winter, an aggressive drilling program by the diamond division of
At the time that Ashton and Soquem were acquiring ground in the Otish Mountains, Majescor was zeroing in on a broad, 45-by-25-km corridor of anomalous kimberlite indicator minerals that it had loosely defined during a couple of seasons of regional glacio-fluvial sediment-sampling in the Otish region. In late 2000, Majescor staked 1,028 sq. km of ground, which covered a large part of the anomalous corridor and adjoined the Ashton and Soquem block to the northeast.
On the strength of the indicator mineral chemistry, BHP Billiton Diamonds struck a deal with Majescor in the summer of 2001 to earn up to a 56% interest in the Portage project by funding all costs through to production. After completing an extensive airborne geophysical survey, followed by till sampling and ground geophysics over some 30 targets, BHP’s drilling program of 18 priority targets was a total bust.
Down-ice
The next round of exploration will concentrate on high-density till sampling in anomalous indicator mineral areas. Responding to market speculation that its kimberlite indicator minerals may have traveled down-ice from a source on Ashton’s ground, Majescor said many of its anomalous sites do not lie directly down-ice from the known kimberlitic bodies. Majescor emphasizes that there are enough barren samples up-ice to suggest that the source should be on Majescor’s ground.
A second high-priority project for Majescor has been its wholly owned Wemindji project, on the east side of James Bay, 400 km west of the Otish Mountains. The project area was previously explored by De Beers, which spent several years trying to find the source
of a 30-km-long indicator mineral dispersion train. De Beers conducted extensive glacial sediment sampling, swept the area with geophysical surveys and unsuccessfully drilled at least nine magnetic anomalies before abandoning the property in 2000. Majescor re-staked the area based on its compelling indicator mineral chemistry, which suggested that a potentially diamond-bearing kimberlitic source lay nearby.
Majescor blitzed the property with a helicopter-borne geophysical survey, further till sampling and test-pitting, plus two rounds of drilling before discovering a series of narrow, near-surface, sub-horizontal kimberlite sills or dykes extending over a 400-by-500-metre area. Cut by 15 holes, the interbedded sills exhibit two styles of kimberlite. The cumulative thickness of the kimberlite intervals is about 2 metres. There is no word on whether the sill is diamondiferous.
Last fall, Dios initiated a helicopter-borne reconnaissance basal till-sampling program over the four properties, collecting 185 samples, which weighed an average of 30 kg each. These included 75 samples on the Eastern block, 46 on the Southern block, 40 on the Northern block, and 24 on the Western block. Three of the properties are down-ice of Ashton and Majescor. The till samples have yielded various indicator minerals, including chrome diopsides, ilmenites and chromites. A single G10 pyrope garnet was recovered from four undisclosed sample sites several kilometres apart, while a fifth site yielded a G9 garnet. Dios considers each of these sites significant because the background in the Otish Mountains is completely barren. Company President Marie-Jose Girard won’t say which property hosts the anomalous pyrope garnets because they are still acquiring ground in the area. Sampling is planned for each of the five anomalous sites. A Dios crew is currently conducting reconnaissance sampling on the Hotish project, farther south in the Beaver Lake area. There, the Montreal-based junior holds five properties totalling 532 sq. km, some of which are within the Mistassini project area of
The Otish Mountains region is relatively unexplored for diamonds. Uranerz Exploration & Mining discovered a kimberlite body in the Beaver Lake area, 180 km south of the Renard kimberlites, during the late 1970s while exploring for uranium.
Tichegami
Last year, after completing further airborne geophysics, Ditem added to its land position by map-staking 205 sq. km in the Tichegami River area, north of the Beaver Lake body.
An airborne magnetic survey was flown over the Beaver Lake and Tichegami holdings in March. Pure Gold then drilled two high-priority geophysical targets at Tichegami and hit 118 metres of diatreme breccia in one of the holes. The H-1 body, which has since been confirmed as kimberlite, is barren of diamonds. The new kimberlite discovery is 20 km north and east of the Beaver Lake kimberlite. This summer, Pure Gold plans to investigate selected airborne anomalies and drill at least three targets in the vicinity of the H-1 discovery. Pure Gold also continues to acquire ground in the Otish region.
West of the Beaver Lake area, at the Mistassini project, Majescor and Canabrava will spend the summer investigating 77 anomalous features with glacial-sediment sampling and geological mapping. In addition, sampling will delineate the known dispersion trains and increase the overall sample density of the project in preparation for drilling, which has been moved back to the fall.
Mineral grains
Canabrava can earn a half-interest in the Mistassini package of claims by spending $1.3 million on exploration. Reconnaissance and follow-up sampling by Majescor has recovered more than 500 indicator mineral grains dominated by ilmenite, with lesser amounts of pyrope garnet and chromite, including some G10s. Majescor remains the operator.
Some of the more active juniors in the Otish Mountain area include
Last fall, till-sampling by
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