It’s back to the drawing board for
Poor weather conditions have forced the junior to suspend drilling activities on its Nanuq project in eastern Nunavut but not before five promising geophysical targets, at the head of a well-developed indicator mineral train, were tested without intersecting any kimberlite.
The cluster of geophysical anomalies was explained by the intersection of pyrrhotitic iron formation and magnetic phases of granite. The company believes additional till sampling and enhanced geophysical surveys will be necessary to define the source of an anomalous corridor of garnet indicator minerals.
The corridor is dominated by G9 pyrope garnets and a good collection of eclogitic garnets in the diamond stability field, as well as olivine, some chrome diopsides, and diamond inclusion chromites. Several of the pyrope garnets display kelyphitic rims, indicating a nearby source.
“The mineral chemistry is really quite nice,” said Dunsmuir President Art Ettlinger during a talk at the 2004 convention of the Prospectors & Developers Association of Canada, held in Toronto. “If we do hit kimberlite, it should be diamond-bearing to some degree.”
Dunsmuir acquired the original 3,400-sq.-km Nanuq property in early 2003. The project had evolved through an agreement with
Under terms of the agreement, Dunsmuir is required to spend at least $1 million annually over five years exploring the specific areas it chooses from BHP Billiton’s database. Should Dunsmuir make a diamond discovery (or, for that matter, a base or precious metal discovery) and complete a mini-bulk sample of at least 25 tonnes, BHP would have the right to back-in for a 60% interest by reimbursing Dunsmuir an amount equal to 300% of its project expenditures to that point. If BHP Billiton elects to fund the project through to production, it can increase its interest to 70%.
A committee consisting of two representatives from each company is responsible for monitoring exploration by Dunsmuir, based on data provided by BHP Billiton.
In the first year of the arrangement, Dunsmuir chose to option a 51% interest in the Moose property in northern Manitoba. The junior spent $740,000 in 2002 and 2003 trying to unravel the complex glacial history of the area. Additional heavy mineral sampling was carried out, in conjunction with ground geophysical surveys on 11 airborne targets derived from a high-resolution airborne magnetometer survey flown by BHP Billiton in October 2000. Seven geophysical targets were tested, but no kimberlite was encountered in any of the holes. The property has since been shelved, and no further work is planned.
Under the arrangement with BHP Billiton, Dunsmuir also acquired an option to earn a 51% interest in the North West Lake property in the Upper Peninsula of Michigan, where a magnetic and gravity airborne feature has been identified. The region is geologically prospective for a wide range of mineral commodities, including copper, gold and Norilsk-type nickel and platinum group elements.
The North West Lake property is 5 km west of the historic mining town of Republic. A ground magnetic survey was completed in March 2003. A follow-up soil geochemical survey was of limited value, owing to the swampy nature of the area. Dunsmuir and BHP Billiton have decided to drill-test this target next winter.
Nanuq is the company’s flagship property. It lies 225 km east-northeast of Baker Lake in Nunavut, midway between the Churchill diamond play, where
Dunsmuir began exploring the Nanuq area in the summer of 2002, based on the results of previous sampling by BHP Billiton Diamonds. BHP Billiton has identified positive kimberlite indicator mineral grains in 23 of 40 widely distributed heavy mineral samples collected as part of a regional reconnaissance program in 2001.
The area is ideal for sampling because the till cover is relatively thin and the glacial history follows a simple, northwest/southeast direction and is therefore easy to interpret.
In 2002, Dunsmuir collected 188 till samples on what became the Nanuq property. Samples were taken at 2-km intervals along grid lines spaced 5 km apart. Kimberlite indicator mineral grains were recovered from 67 of the 188 samples. Another 93 samples contained forsteritic olivine — in some cases, thousands of grains. Ultramafic sources, rather than kimberlite, may account for some of this olivine.
The results helped define a 6-km-wide anomalous corridor of kimberlite indicator minerals extending across the northeastern part of the property for a distance exceeding 36 km. The head of this well-defined mineral train is near the property boundary with the proposed Ukkusiksalik (Wager Bay) National Park. The distribution of indicator mineral grains in the dispersion train indicated that there was possibly more than one kimberlite source in the area.
Reconnaissance sampling also identified a second anomalous area, 15 km southwest of the main Nanuq train, and there are indications of a third dispersion train, 40 km down-ice on the southern part of the property. Indicator mineral grains found in these additional areas included diamond inclusion chromites and eclogitic garnets, plus G9 and G10 pyrope garnets, chrome diopsides and olivines. Two follow-up samples near the interpreted head of the second train returned what are considered high counts for this region — one with 10 pyrope garnets, eight eclogitic garnets, four chrome diopsides and one chromite, and the other, with 15 pyropes, seven eclogites, four chrome diopsides and two chromites.
Dunsmuir increased its land position at the beginning of last summer by staking a land package of 2,533 sq. km adjoining the southern and eastern boundaries of Nanuq. The company returned to the field last July, collecting 472 additional infill till samples and completing 12,000 line km of high-resolution magnetic airborne surveys at 150-metre-line spacing. In the Nanuq South area, 260 till samples were collected for indicator mineral analysis.
The geophysics identified 95 or so geophysical anomalies, including seven high-priority targets at the head of the main Nanuq mineral train. Ettlinger said the geophysical data were interpreted independently of the indicator mineral chemistry.
Dunsmuir and BHP Billiton Diamonds are planning a program that would cover additional sampling and geophysics at Nanuq.
Formed in the summer of 2002 by Frank Giustra and the principals of Endeavour Financial, Dunsmuir explores for diamonds both in Canada and the U.S. Ettlinger, the president, is a geologist and former mining analyst with Yorkton Securities. The board of directors includes Ettlinger, two individuals from Endeavour, Neil Woodyer and Gordon Keep, plus Clive Johnson, president and founder of Bema Gold. Jennifer Pell rounds out the team as vice-president of exploration.
Thelon claims
This past winter, Dunsmuir acquired control of 899 sq. km of claims in the Lac de Gras district, including an option to earn up to a 65% interest in 11 claim blocks held by
“We acquired this land because portions of these blocks have never been thoroughly explored,” said Ettlinger. “When these blocks were in the hands of previous operators, they did not know the distribution of the kimberlites. But more than 250 kimberlites have now been found in Lac de Gras, and these follow regular structural distributions or geometric patterns that are controlled by structures.”
Dunsmuir has since granted
Dunsmuir has subjected the remainder of its Lac de Gras holdings to an airborne geophysical survey, which will be followed by indicator mineral sampling.
Meanwhile, in the U.S., Dunsmuir is exploring for diamonds in partnership with
100+ locations
“We’re looking for the sources of thousands of alluvial diamonds that have been found at more than a hundred locations in the U.S., that is, outside the classic diamond exploration areas,” said Ettlinger. “Most of the diamonds that have been found in the U.S. range from about a third of a carat to seven-to-eight carats in size.”
Ettlinger noted the non-traditional, highly unusual find in Wawa, Ont., where diamonds up to three-quarters of a carat in size have been recovered from Archean-age, metamorphosed ultramafic rocks.
“In areas where there have been alluvial diamonds recovered, we are going out and sampling rock bodies we think could be deep-seated ultramafic rocks and which may have brought diamonds to the surface,” explained Ettlinger. The Dunsmuir-Majescor joint venture recently expanded its U.S. search to traditional kimberlite discoveries based on a target database generated by U.K.-based
Dunsmuir and Majescor will have the right to earn up to a 60% interest in any properties acquired in the project area by spending a total of US$726,500 on exploration over four years and paying US$60,000 in outstanding obligations owed by Firestone.
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