Ataa Sund Kimberlitic Diamond
The Ataa Sund kimberlite diamond project area is located in the vicinity of Arveprinsen Ejland in eastern Disko Bay. It comprises two Avannaa licences; the entire 933 km2 of licence 2008/33 and sub area 4 of licence 2007/52. Avannaa discovered diamonds in a dyke of kimberlitic affinity in 2007 at Qeqertaa Island. The sample returned a very promising diamond count considering the size of the sample and was the subject of a press release on 18 February 2008. The project area contains other potentially diamondiferous intrusions at Ataa Hills, Anap Nunaa, and mainland east of Ataa Sund.
The dyke is at a highly accessible fjord-side location. It is sub-vertical, up to 8m wide and with an indicated strike length of at least 2000m. Along the strike length, there are several exposures, and glacial overburden is generally less than about one meter. The dyke is one of many dykes of kimberlitic-lamproitic affinity that occur in this region that have been mapped as “ultramafic lamprophyres” by survey geologists. It should be noted that whilst these rocks have been called ultramafic lamprophyres, this has been used as a field term to describe any potassic ultramafic rock and does not preclude a kimberlite or lamproite classification.
A 39kg sample collected from Qeqertaa in 2007 and analysed by SGS Lakefield yielded 102 diamonds with a total weight of 0.013 carat. One stone can be characterized as a macrodiamond with dimensions of 0.83×0.66×0.53mm, translucent and white with graphite inclusions, while the remaining 101 stones are all microdiamonds. In terms of colour, 95 stones are white and 7 are off white, and in terms of clarity, 62 stones are transparent and 60 translucent. The majority of the stones (76) are crystal fragments suggesting a high probability that larger stones are present. Graphite inclusions are present in 90 stones. The size distribution is given in Table 3.
| Distribution of diamonds recovered from the Qeqertaa dyke, Aug 2007. | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Sample ID | Sample weight | +0.106 mm | +0.15 mm | +0.212 mm | +0.3 mm | +0.425 mm | +0.6 mm | +0.85 mm | total |
| 252523 | 39 kg | 44 | 34 | 11 | 12 | 1 | 0 | 0 | 102 |
A 433 kg sample was collected from the same location during the 2008 field season. It was analysed by SGS Lakefield and yielded 1487 diamonds of which 10 are larger than 0.6mm. The three biggest stones are retained on the 0.85mm sieve and measure 1.45×1.03×0.45mm; 1.28×1.25×0.94mm and 1.20×1.05×1.01mm. The three stones are all transparent; two are white and one off white. All three are free of inclusions and hence of excellent quality. In the 0.6-0.85mm size fraction, five out of the seven stones are crystal fragments, suggesting presence of larger stones in the source region of the Qeqertaa diamond sample.
| Distribution of diamonds recovered from the Qeqertaa dyke, Aug 2008 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Sample ID | Sample weight | +0.106 mm | +0.15 mm | +0.212 mm | +0.3 mm | +0.425 mm | +0.6 mm | +0.85 mm | total |
| 252547 | 433.49 kg | 688 | 451 | 215 | 98 | 25 | 7 | 3 | 1487 |
Acquisiton of nearly 2000 line km of airborne magnetic survey has helped direct exploration efforts in 2009 and 2010. An additional 1400 line km have been planned for acquisition in spring 2010. A ten tonne bulk sample is being processed and the results will become known in Q1 2010.
