The Mt. Milligan North property, comprising 30 mineral tenures with total area 11,746 hectares, is located 165 km northwest of Prince George, British Columbia, Canada, in proximity to the Mt. Milligan copper-gold mine that is currently undergoing pre-production development.
The Mt. Milligan North mineral tenures are located in volcaniclastic rocks of Middle Triassic to Lower Jurassic age in Quesnellia terrane of the Intermontane physiographic belt of interior British Columbia, five to seven kms north northwest of the Mt. Milligan mine site where a copper-gold mine with 60,000 tonne per day capacity is being readied for production. Mt. Milligan mineral deposits are located in proximity to small feldspar porphyritic quartz-poor monzonitic intrusive bodies. Chalcopyrite occurs as fine-grained dissemination and is accompanied by pyrite and magnetite; bornite is a minor component and potassic and propylitic alteration are present throughout the deposits.
The Mt. Milligan North mineral tenures were located on the basis of a geological setting closely analogous to the host environment of most of the Cordilleran porphyry deposits, proximity to Mt. Milligan mine site, presence of alkalic volcanic rocks accompanied by potassic and propylitic alteration, nearby presence of porphyritic monzonitic and other quartz-poor, potassium-rich intrusions, strong magnetic intensity, weak history of prospecting and geological investigations but extensive database of regional technical information. A 2010 program of geochemical soil sampling comprising 612 soil samples analysed by MMI (mobile metal ion) methods provides partial coverage of a number of areas of strong magnetic intensity. MMI is a partial leach method that measures the presence of metal ions derived from underlying bedrock and transported to the surface environment. MMI techniques are relatively recently developed procedures that have been credited with detecting “blind” ore bodies in a variety of terrains.
The Mt. Milligan North mineral tenures are prospective for Mt. Milligan look-alike mineral deposits: that is, for large low grade copper-gold deposits. The exploration concept includes:
- Quesnellia arc-related terrane that is host nearby and elsewhere in British Columbia to a large number of very significant base metal deposits
- proximity to the Mt. Milligan mine development site where resources of several million ounces of gold and several billion pounds of copper have been confirmed by drilling and other studies
- known presence of alkalic volcanic rocks, including latites and andesites similar to those present at Mt. Milligan
- location of mineral tenures astride a northwest trend of porphyritic monzonitic, gabbroic and quartz poor granitic intrusions
- position covering a well defined magnetic “high” pattern that is smaller than but with similar intensity to the magnetic pattern at Mt. Milligan
- prevalence of glacial-fluvial sand and gravel deposits that historically have inhibited prospecting and potentially have masked copper-gold mineralization
- availability of a relatively new geochemical technique that elsewhere has been successfully applied to mineral search in areas of similar cover conditions
- access to a sizeable database of technical data, including reconnaissance geochemical surveys and regional airborne geophysical surveys, assembled by Geoscience BC and the Geological Survey Branch of the provincial Ministry of Energy and Mines.
A two-part program of exploration work is recommended: Stage 1 work will expand coverage by technical surveys, including soil geochemistry, prospecting and ground-based geophysical surveys, and photogrammetric studies, including structural interpretations of fracture patterns, and analysis of satellite-based spectrometric data. Geophysical work may include magnetic surveys and induced polarization surveys performed by a specialist contractor. An experienced prospector should be attached to the field program and given a mandate to independently examine all parts of the property and sample or otherwise investigate mineral zones. Budget requirements are estimates and actual costs of field work may differ from those estimates.
Proposed soil sample lines, totalling 44.5 line-km and 903 samples, are detailed in Figures 12 and Table 2 of this report. Ground-based magnetic surveys should be conducted over the same lines. The Phase 1 exploration budget should include provision for 20 line-km of induced polarization surveys over parts of the soil survey that will be determined as work progresses.