The Nugget (West Cirque) occurrence is in the southwest headwaters of a northwest-flowing creek that drains into Duncan Lake, approximately 2.5 kilometres to the northwest, about 191 kilometres north-northwest of the community of Germansen Landing.
The Toodoggone district lies within the eastern margin of the Intermontane Belt and is underlain by a northwest-trending belt of Paleozoic to Paleogene sediments, volcanics and intrusions covering an area of 90 by 25 kilometres. The basement rocks are Proterozoic metasedimentary equivalents of the Hadrynian Ingenika Group. These rocks are unconformably overlain by volcanic and sedimentary units of the Devonian to Permian Asitka Group, which are in turn overlain by Upper Triassic basaltic to andesitic flows, volcaniclastics and minor limestone of the Stuhini Group. Volcaniclastic rocks of the Lower Jurassic Hazelton Group and rhyolitic to dacitic flows, intrusions and volcaniclastics of the Lower Jurassic Toodoggone Formation (Hazelton Group) overlie the Stuhini Group. Further to the west, nonmarine sediments of the Cretaceous Sustut Group overlie the volcanic strata and form the western margin of the district.
The Early Jurassic Black Lake Suite, of quartz monzonitic to granodioritic composition, has intruded the older strata in the central and eastern parts of the region and forms the eastern margin of the Toodoggone district. Within the district, syenomonzonitic and quartz feldspar porphyritic dikes may be feeders to the Toodoggone Formation.
Locally, the area is mainly underlain by andesitic to basaltic volcanics of the Stuhini Group, except for the eastern regions, which are underlain by fragmental tuffs of the Toodoggone Formation. Lower Jurassic stocks, dikes and possible sills of quartz monzonite to quartz diorite composition have intruded the Stuhini Group. Porphyry-style copper-gold mineralization occurs mainly within Black Lake intrusive and Stuhini volcanic rocks and, to a lesser extent, the lowermost Toodoggone Formation rocks. See Kemess North occurrence (094E 021) for a detailed description of the regional geology.
Mineralization and alteration styles for the Nugget copper-gold porphyry occurrence are not fully described but are assumed to be similar to that of the nearby Kemess North occurrence. The alteration and mineralization are described as becoming more irregular from the Kemess North deposit to the Nugget zone as intrusive units approximate steeply dipping dikes. The mineralized zone occurs with in a broad sericite alteration zone with irregular zones of chlorite-biotite alteration and disseminated magnetite and quartz-magnetite veining associated with chalcopyrite. Minor amounts of zeolite occur locally in late stringers. Copper-gold mineralization occurs with in the volcanics adjacent and proximal to the monzonite apophyses at depths exceeding 400 metres.
Unique to the Nugget zone, are high grade sections of epidote-magnetite-garnet skarn with clots of pyrite. Mineralization occurs as calcite-pyrite-chalcopyrite and quartz-calcite-epidote-pyrite-magnetite-chalcopyrite veinlets and as coarse clots of pyrite-chalcopyrite within carbonate. Rare native silver and alunite is also reported, and gypsum occurs locally as intergrowths within calcite. The gold-copper skarn mineralization overprints the gold-copper porphyry-style mineralization. The Nugget zone generally exhibits a higher gold to copper ratio than the Kemess North deposit, with narrow intersections of up to 8 grams per tonne gold (Assessment Report 27083).
Another zone of similar copper-gold porphyry mineralization, referred to as the Sovereign zone, is located approximately 1 kilometre to the southeast.
The area has been historically explored in conjunction with the nearby Kemess North developed prospect (094E 021) located 1.2 kilometres northeast and the Kemess South past-producing mine (094E 094) located 5.6 kilometres south.
During 1966 through 1971, Kennco Explorations Ltd. completed programs of geochemical sampling and geological mapping on the area immediately west as the Kemess 1-100 claims. In 1975 and 1976, Getty Mines Ltd. examined the property and completed programs of soil sampling and geological mapping on the area immediately west.
During 1986 through 1989, El Condor Resources Ltd. completed programs of rock and soil sampling, geological mapping, trenching and a 14.1 line kilometre ground magnetic survey on the area immediately west as the New Kemess 1-2 claims. In 1990 and 1991, El Condor Resources Ltd. conducted programs of geological mapping, geochemical sampling and a 201.0 line kilometre induced polarization survey on the area as apart of the Kemess property. Also during this time, six diamond-drill holes (91-52 to 91-57) totalling 900.16 metres were completed on the Nugget zone.
In 2002, Northgate Minerals Corp. conducted a 58-hole diamond drilling program, totalling 33,686.3 metres, on the Kemess property, including 12 drillholes on the Nugget zone. Drilling highlights included intercepts of 0.20 and 0.13 per cent copper with 0.45 and 0.55 gram per tonne gold over 56.40 and 60.01 metres, respectively, in drillhole KN-02-23; 0.08 per cent copper and 1.27 grams per tonne gold over 12.74 metres in hole KN-02-30; 0.16 per cent copper and 0.46 gram per tonne gold over 100.00 metres in hole KN-02-43; 0.19 per cent copper and 0.45 gram per tonne gold over 115.64 metres in hole KN-02-48; 0.19 per cent copper and 0.36 gram per tonne gold over 15.65 metres in hole KN-02-49; 0.21 per cent copper and 0.39 gram per tonne gold over 118.09 metres in hole KN-02-51, and 0.34 per cent copper with 8.35 grams per tonne gold over 2.00 metres in hole KN-02-56 (Assessment Report 27083).
As of December 31, 2002, the inferred resource for the Nugget zone was reported at 87,000,000 tonnes grading 0.38 gram per tonne gold and 0.16 per cent copper (www.northgateexploration.ca, January 8, 2004).
In 2003, Northgate completed more than 10,000 metres of exploration drilling on Kemess North and several nearby prospects. Twelve holes were drilled at the Nugget porphyry gold-copper prospect. Hole KN-03-12 intersected 419 metres averaging 0.38 gram per tonne gold and 0.13 per cent copper starting at a depth of just 24 metres (Exploration and Mining in British Columbia 2004, page 43). The area of shallow mineralization will be further evaluated for its potential to be a satellite orebody.
In 2004, Northgate completed 7561 metres of drilling on the Kemess property with seven holes, totalling 2423.2 metres, being completed on the Nugget porphyry gold-copper zone in an attempt to expand on encouraging near-surface mineralization intersected in 2003. Drilling yielded intercepts of up to 0.47 gram per tonne gold and 0.11 per cent copper over 349 metres in hole KN-04-15 and 0.38 gram per tonne gold with 0.10 per cent copper over 330.7 metres in hole KN-04-04 (Assessment Report 27675). The mineralized zone was reported to be open to the west with a pittable resource of 9.4 million tonnes grading 0.363 gram per tonne gold and 0.069 per cent copper (Assessment Report 27675).
During 2005 through 2011, Northgate completed further programs of prospecting, geological mapping, geochemical sampling, ground geophysical surveying and diamond drilling on the Kemess and Kemess East properties.
During 2013 through 2017, AuRico Gold Inc. examined the area as part of the Kemess and Kemess East properties.
