Northgate Minerals: New Porphyry Discovery in B.C

The Kemess mine in Northern B.C. consists of an open pit copper-gold mine, and several undeveloped deposits. The topography is varied, including regions of gentle slopes and rugged mountain terrain. Previous drill testing had returned encouraging results, but was unsuccessful in outlining the prospective mineralization. To assist exploration, a Titan 24 survey was designed and tested prior to the actual survey. Titan 24 has been proven to detect copper porphyry ore bodies at depths of 1400 metres by Rio Tinto at the Resolution discovery, and can differentiate large high tonnage potential deposits from small mineralized bodies-providing effective drill targeting.

Challenges

Porphyry targets, although typically large, can be found at a variety of depths, often in areas of extreme topography and talus. The standard approach to exploring for porphyries has included geochemistry, drilling and traditional depth-limited geophysics.

Survey

A geological model was developed with several zones of potential mineralization to test Titan's DC IP sensitivity to mineralization at depths ranging from 300 to 600 metres. Plans were made to utilize helicopter support for crew and equipment placement along a 5 kilometre line.

Forward Model Study Results

The chargeability forward model and resulting inversion indicated that potential zones would be well resolved to depths below 400 metres, and that a survey would be beneficial. A cross line was then planned, assuming the results from the longitudinal line were favourable.

Titan 24 Results

The survey outlined several previously unknown exploration targets. Titan data worked extremely well in mapping the sulfide-rich cap zones to depth. The proposed mineralized geologic model was corroborated and drilling could then be focused into specific target regions for further exploration. Barren zones may be considered significantly explored.

 

Follow-up Drill Results

The Ora Zone discovery was made from a drill program designed to test the deep Titan 24 chargeability anomaly that was defined in 2006. Hole KH-07-04 intersected the longest mineralized interval ever drilled on the Kemess property with 441.3 metres of 0.38 g/t gold and 0.391% copper. This hole also represents the deepest mineralization (850 metres deep) so far discovered in the Kemess camp, and due to its grade and thickness it represents a very exciting discovery. The MT mapped the Ora zone where copper mineralization was found at a depth of 700 metres. While the relationship between this mineralization and the Kemess North deposit is unknown, the Titan 24 results and this new discovery suggest that the Kemess North mineralizing system is far more extensive than previously understood.

“A third large gold-copper porphyry system discovered at Kemess…. The discovery of another large mineralized system in the Kemess camp is very exciting. Equally important is the success of the Titan 24 deep penetrating survey, which has proven to be an excellent predictive tool for spotting drill holes…”   Ken Stowe, President and CEO