Ashton hits apparent kimberlite at Otish

Ashton Mining of Canada (ACA-T) has intersected what appears to be kimberlite in the first hole of a drilling program in the Otish Mountains region of north-central Quebec.

A vertical hole drilled into the first geophysical target hit a 98-metre interval of ultramafic igneous rock, with characteristics that are described by Ashton as “consistent with kimberlite.” The hole was shut down in kimberlitic material at a depth of 108 metres. The intrusive body is covered by 10 metres of overburden.

Indeed, Ashton’s geologists in the field identified the discovery as kimberlite, though the company is taking a more cautious approach and won’t make a definitive call until petrographic laboratory tests have been completed.

The geophysical target lies partially on land and partly under a lake. A second hole, at the same site, was collared at an angle of minus 70; it intersected 108 metres of kimberlitic material before shutting down while still in the unit. Ashton spokesman Ariel Bowers says the two holes were cut short because of budgetary constraints. “We want to punch in as many holes as possible within the budget.” Ashton intends to test up to four targets during the first round of drilling.

Ashton holds more than 1,760 sq. km in the Otish Mountains area in a joint venture with Quebec government-owned Soquem. Since 1996, the pair has been searching for diamonds in the northern Quebec portion of the Superior Craton. After carrying out reconnaissance programs of heavy mineral sampling and airborne magnetic surveys on more than 450,000 sq. km of prospective terrain, the joint venture initially staked 1,000 sq. km of key ground in two areas of Quebec during the second half of 2000. Ashton zeroed in on the Otish Mountains region, 275 km northeast of Chibougamau, and the Caniapiscau area, 500 km east-northeast of Radisson.

Heavy mineral sampling defined several highly anomalous indicator mineral dispersion fans, with some samples containing more than 1,000 indicator grains. “We are particularly encouraged by the elevated concentrations of indicator minerals and high percentage of G10 pyrope garnets in some samples,” President Robert Boyd told shareholders at the annual meeting in April.

Ashton flew a geophysical survey over the original central property in the Otish Mountains claim group in late 2000 and followed up with ground geophysics over eight targets in March. The summer was spent further investigating these anomalies, with more than 350 heavy mineral samples collected.

Also active in the area is Majescor Resources. The junior began ground investigations of regional airborne magnetic anomalies in 1998, which led to the recovery of one garnet from each of two till samples collected in a vast plain. Follow-up work in the summer and fall of 1999 generated a broad, loosely defined 25-by-45-km corridor of anomalous kimberlite indicator minerals in glacio-fluvial sediments. This anomaly was better defined in 2000 through a program of glacial sediment sampling in which close to 600 samples were taken. Once Ashton started staking ground in the Otish Mountains area, Majescor responded by acquiring 1,028 sq. km of ground covering a large part of the indicator mineral anomaly, down-ice from Ashton. Within the anomaly, Majescor says the indicator mineral population is dominated by peridotitic garnet (20-25% are classified as G10s), followed by picroilmenite.

BHP-Majescor deal

BHP Diamonds, a wholly owned subsidiary of BHP Billiton (Bhp-N), struck a deal with Majescor this past summer to earn up to a 56% interest in the Portage property block by funding all costs through to production. BHP has completed an 8,500-line-km airborne geophysical survey and is carrying out ground investigations of selected airborne anomalies, including follow-up till sampling.

As diamond exploration in the Otish Mountains area begins to heat up, the first known kimberlite body in the region was discovered by Uranerz Explorations & Mining in the late 1970s while exploring for uranium. The diamondiferous kimberlite lies 50 km south of Ashton’s property package. Ditem Explorations (DIT-M) entered into an option agreement with Uranerz in 1998 and can earn a 49% interest in the property by spending $1.5 million over four years. Inco‘s (N-T) exploration subsidiary, Canico, retains a 2% production royalty.

Mixed results

Ditem initially tested the kimberlite with six core holes in 1998 and recovered four macrodiamonds from selected samples weighing 96.1 kg. (A macro is here defined as measuring greater than 0.5 mm in at least one dimension.) The largest stone recovered measured 0.96 by 0.6 by 0.56 mm. However, a follow-up, 7-tonne mini-bulk test sample yielded no diamonds above a 0.8-mm square-mesh screen size.

Ditem carried out additional work in 1999, consisting of an aeromagnetic survey and limited drilling, resulting in the discovery of lamprophyric material. The junior map-staked additional ground in the Techegami River area this past spring after completing further airborne geophysics.