SouthernEra finds kimberlite at Munn Lake — Drill-testing uncovers narrow kimberlite body

Toronto-based SouthernEra Resources (SUF-T) may have found the source of diamond-bearing kimberlite float boulders at the Back Lake project in the Northwest Territories.

The company discovered a kimberlite sill while conducting a 10-hole diamond drilling program. Results from previous sonic drilling had suggested that a kimberlite body was associated with a north-northwesterly trending lake-bottom depression.

The recent program tested an area measuring 300 by 150 metres. Eight of the holes intersected kimberlite with an estimated true width ranging from 0.25 to 12 metres. The kimberlite sill dips about 30 to the northeast and remains open along strike and downdip.

SouthernEra says the kimberlite hosts up to 60% eclogitic xenoliths, and present in the core are chrome diopsides up to 8 cm long, pyrope and eclogitic garnets, picroilmenites and chromites. More than 40% of the recovered pyrope garnets are said to occur in the G-10 field. Microdiamond results from a 50-kg core sample are pending.

The kimberlite float boulders were discovered in the summer of 1997 on the western shores of Munn Lake. The float material, which contains boulders up to 25 metres in diameter, yielded 62 macrodiamonds and 164 micros from a 581-kg sample. (A macro is defined as measuring more than 0.5 mm in at least one dimension.) The largest recovered diamond weighed 0.12 carat, with one other weighing 0.03 carat and three weiging 0.01 carat.

The Back Lake project is 100 km south of the Lac de Gras region. SouthernEra is the operator and holds a 70% interest. The remaining interest is carried, with Kalahari Resources (KLA-V) holding 19.38% and Island-Arc Resources (IAR-V) owning 10.62%. Kennecott Canada Exploration, a division of London-based Rio Tinto (RTP-N), holds a back-in right to earn a 30% interest from SouthernEra.

Elsewhere in the territories, the drill testing of five geophysical targets at the Yamba Lake property has resulted in the discovery of a new narrow kimberlite body, dubbed S141. SouthernEra can earn a 51% interest in the property from Tanqueray Resources (TQY-A) and partner Mill City International (MIY-V) by spending $10 million on exploration over four years. Tanqueray and Mill City each hold a 44.5% interest in Yamba Lake, whereas Cypango Ventures (CAV-V) holds 11%.

Yamba Lake lies 46 km north of the Ekati diamond mine. Previous work has identified six kimberlite pipes, including the Ptarmigan and T-10.

The S141 discovery hole was collared at minus 45 into an elongated, land-based magnetic low, 3 km southeast of the Ptarmigan pipe. A 14.75-metre interval of kimberlite was intersected at a down-hole depth of 62-76.7 metres. A second hole is testing the dimensions of this new discovery.

To date, 29 airborne geophysical targets have been followed-up with ground magnetic and electromagnetic surveys, which are continuing on additional targets.

SouthernEra also re-tested the Ptarmigan pipe with one new hole, and the T-10 pipe, with three. Ptarmigan has yielded indicator mineral microprobe chemistry results that suggest diamond potential, whereas past microdiamond results from T-10 include the recovery of six macros and 62 micros from 83.6 kg of sample.

The processing of more than 1,000 till samples collected from the property last summer continues to yield positive results. Several pyrope garnets with “excellent G-10 chemistry” have been recovered from samples, SouthernEra says, adding that these results suggest good potential for the discovery of further kimberlite bodies.

SouthernEra expects to keep drilling into the summer as it evaluates land-based and near-shore kimberlite targets.

On the Lac de Gras property block, preliminary microdiamond results have been returned from the EG-5 kimberlite pipe, discovered earlier this year by Kennecott. A 129.4-kg sample of core from the third hole yielded one macro and 27 micros. The EG-5 kimberlite was found in shallow water about 75 metres from the southern shore of Lac de Gras. Four holes were drilled into the pipe. The first two holes were lost, and the third hole recovered 46.7 metres of kimberlite before being abandoned as a result of difficult drilling conditions.

A fourth hole pulled 183 metres of kimberlite, ending in kimberlite. Pending are microdiamond results from more than 600 kg of sample recovered from hole 4.

The Lac de Gras block is contiguous with the southern boundary of the Ekati mine property and is a 60-40 joint venture between Kennecott and SouthernEra.

A land-based, narrow, intrusive kimberlite body discovered by Kennecott on the DHK claim block at the southwestern end of Lac de Gras yielded six micros from a 7-kg sample. A 2.1-metre true width interval of volcaniclastic kimberlite was encountered 150 metres northeast of the DD42 kimberlite body. The kimberlite consists of 70% olivine and up to 1% purple pyrope garnets.

Kennecott can earn a 51% interest in the DHK block, leaving SouthernEra with a 25% stake and DHK Resources with the remainder. DHK Resources is owned equally by Dentonia Resources (DTA-V), Horseshoe Gold Mining (HSX-A) and Kettle River Resources (KRR-T).