The West Fork zone of the Galore Creek deposit is located at the headwaters of Galore Creek, a northerly flowing tributary of the Scud River, some 85 kilometres south-southwest of Telegraph Creek.
At least twelve alkalic porphyry copper-gold deposits are known to occur within the Galore Creek syenite complex. This complex comprises a series of Late Triassic to Early Jurassic orthoclase-porphyry syenitic bodies which have intruded coeval Upper Triassic Stuhini Group volcanic rocks and related sediments. Faults which offset and segment the intrusive rocks and a sub-horizontal fracture cleavage are the two main structural elements in the syenite complex. The complex is roughly 5 by 2.5 kilometres in area.
The deposits are hosted primarily by highly altered potassium- enriched volcanic rocks and pipe-like breccias adjacent to syenite dikes and stocks. Typically, the deposits are manto-shaped and have a north to northeast trend related to the syenite contacts and zones of structural weakness.
The syenite complex is made up of four intrusive phases that are most closely associated with the copper deposits. Six other phases are recognized but are peripheral to the Central zone deposit. The copper-bearing rocks near the syenite intrusion are extensively metasomatized, recrystallized and locally brecciated. These may include pyroclastic and intrusive breccia, trachyte, phonolite, lithic tuff, crystal tuff, pyroxene basalt, pyroxene andesite and minor sediments. These rocks have been converted to skarns and fenitic porphyroids so that original rock types are unclear. The term "hornfels" was frequently applied to these meta-volcanic rocks in the early stages of exploration.
Alteration and mineralization are contemporaneous and spatially overlap. The hydrothermal system was extensive and the resultant alteration led to the formation of large gossans. Potassic alteration consisting of potassium feldspar, titanium biotite and magnetite have converted the syenites and volcanic rocks to pink, white and orange rocks composed mostly of orthoclase. Alteration of pyroxene, hornblende and biotite to assemblages of chlorite and calcite plus/minus albite and epidote characterizes the propylitic zone, best developed in the syenitic rocks. Calc-silicate alteration consisting of abundant garnet, diopside, epidote, albite and anhydrite is an unusual feature of the complex. Garnet replaces up to 50 per cent of the metavolcanic rocks and infills breccias near the northern end of the Central zone breccia pipe but is generally absent from the other deposits. However unusual this metasomatic overprint is the distribution of sulphides, precious metal and magnetite is considered consistent with the expected zoning pattern for alkalic porphyry deposits.
The West Fork Glacier deposit lies beneath a glacier just over a kilometre south of the main Central zone deposit. Barr (CIM Bulletin July 1966) briefly describes the deposit: "The area initially attracted attention because of high copper contents in stream sediments in the West Fork drainage near the toe of the glacier. Selection of the first drill site on the glacier was influenced by the presence of a small magnetic high anomaly in the general area of interest. On the basis of limited information, the deposit is inferred to strike northeast and dip steeply. Mineralization includes chalcopyrite, bornite, pyrite and magnetite as disseminated and massive replacements in equigranular leucosyenite, syenite porphyries, xenolithic syenite porphyry and syenite breccia. Alteration products include chlorite, gypsum, carbonate and orthoclase."
In 2004, NovaGold continued to work in its West Fork zone. While Novagold calls this a new zone, it is in the same vicinity as, or just north of, the West Fork Glacier occurrence. Drilling on the newly identified West Fork target located 700 metres south of the Southwest deposit, intersected an exceptionally high-grade, near-surface zone of mineralization (the Opulent Vein) containing semi-massive to massive bornite, chalcopyrite and magnetite mineralization with bonanza grades of copper and silver with significant gold. One drill interval yielded 14.8 per cent copper, 88.6 grams per tonne silver and 2.05 grams per tonne gold over a 33.6 meter core length (Press Release, October 12, 2004, NovaGold Resources Ltd.). In addition to the shallow high-grade zone, a second broad, relatively flat-lying zone of more typical disseminated bornite and chalcopyrite mineralization has been intercepted below the high-grade zone at West Fork. The mineralization has been defined over an area of 500 by 400 meters, is up to 65 metres thick and remains open to the north and west in the direction of the Southwest deposit.
An NI 43-101 compliant resource estimate for the West Fork is given at 15,100,000 tonnes of Measured and Indicated ore grading 0.58 per cent copper, 0.38 gram per tonne gold and 4.79 grams per tonne silver and; 45,400,000 tonnes of ore in the Inferred category grading 0.47 per cent copper, 0.34 gram per tonne gold and 4.99 grams per tonne silver (Updated Preliminary Economic Assessment, NovaGold Resource Inc., http://www.novagold.net, October 2005).
In 2006, NovaGold completed 33,575 metres of NQ and HQ-sized diamond drilling in 57 holes on the Galore Creek Property. One hole totalling 526 metres, had as its main objective to further extend the presence of high-grade copper and gold within the West Fork Area
In 2007, NovaGold completed 13 holes, totalling 5402.37 metres on the Galore Creek property for the Galore Creek Mining Corporation (GCMC). Drilling focussed on the Southwest Zone, Central Replacement Zone, Butte Zone and reconnaissance targets for the purpose of extending and upgrading known mineralization, identifying grade controls, and collecting geotechnical information for engineering studies. GC06-0751 and GC07-0757 extended the West Fork deposit to the northwest and the mineralization is still open in that direction.
Refer to the Central Zone deposit (104G 090) for further information on the Galore Creek deposits. Further details of a common work history and 2011 reserves and resources are given.
