Led by promising indicator mineral chemistry,
A vertical hole tested the centre of a roughly circular magnetic anomaly and intersected kimberlite from 14.6 metres onward. The hole was shut down in kimberlite at a predetermined depth of 100 metres. The magnetic feature is more than 200 metres in diameter, based on the interpretation of airborne magnetics. Cumberland intends to drill a second angle hole into the discovery once each of the 11 designated targets have been tested with a single hole to a depth of 100 metres. It should take Cumberland to mid-June to complete the first round of drilling.
Drill core from the new discovery is described as a mixture of hypabyssal macrocrystic kimberlite and heterolithic breccia in a kimberlite matrix. The kimberlite is fine-grained and dark grey, and contains olivine as fine grains and macrocrysts. The breccia consists of xenoliths of metasediments that are likely derived from the host Archean Rankin Inlet Group. Core samples will be submitted for microdiamond analysis.
The kimberlite discovery on the Meliadine East project in eastern Nunavut represents a potential new field of kimberlites. Covering 338 sq. km, the project is a 50-50 joint venture between Cumberland and Comaplex, 20 km north of Rankin Inlet. The project area is underlain by metasedimentary and metavolcanic rocks of Archean age.
The area has been the focus of gold exploration. In 2002, the pair started investigating distinct circular magnetic features outlined from a regional aeromagnetic survey completed over portions of the Meliadine property in 2001. Limited till sampling was conducted down-ice of these targets last summer, and a 4,000-line-km airborne magnetic survey was flown in the fall, identifying more than 25 obvious circular features.
Of the 82 till samples collected, 64 contained kimberlite indicator minerals, with multiple grains occurring in 19 samples. The latter samples contained 155 of the 234 indicator mineral grains recovered, including various combinations of olivine, ilmenite, garnet and chromite. Eight purple kimberlite garnets were recovered from seven samples. Two of the garnets had diamond-associated G10 sub-calcic compositions. Eleven of the 18 recovered chromite grains were classified as kimberlitic, with one grain bearing diamond-inclusion-type chemistry.
“From the chemistry I have seen from some of these till samples, I think we’re in the right ball park,” says Glen Dickson, a Cumberland director.
During the 2001 field season, crews collected 64 regional till samples from the Churchill project area. Eighty-five possible kimberlite indicator mineral grains were picked from 21 of the samples. Mineral grains included pyrope and eclogitic garnets, chromites, ilmenites, chrome diopsides and olivines.
Shear Minerals funded further regional sampling in 2002. Anomalous indicator mineral grains were recovered from 27 of the 130 samples collected. One of these samples contained 45 pyrope garnets and two eclogitic garnets. Of the total 107 pyrope grains recovered, 46% were defined as G10 sub-calcic pyropes. Additionally, two separate occurrences of kimberlite float were discovered on the Churchill holdings in a corridor of anomalous indicator grains.
Last fall, a 16,307-line-km fixed-wing aeromagnetic survey was completed. An independent review of the geophysical data revealed 217 potential kimberlite targets, including 29 designated high-priority. In March, ground geophysics was conducted over 30 of the anomalies, further refining 23 drill targets.
The Churchill partners have approved a $2.5-million exploration program this year. Shear has half a million in the bank and is raising an additional $2 million by way of a private placement of up to 4 million units priced at 50 each.
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