Alkaline Rocks and Carbonatites of the World

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Galore Creek

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Occurrence number: 
031-00-015
Country: 
Canada
Region: 
British Columbia
Location: 
Longitude: -131.47, Latitude: 57.02

Situated at the headwaters of Galore Creek, a tributary of the Scud River, the area consists of a sequence of moderately to intensely altered volcanic rocks which have been intruded by a number of syenites. The volcanics include pyroclastic and intrusive breccias, lithic and crystal tuffs, pyroxene andesites, and trachytes and phonolites as flows or possibly sills. Pseudoleucite phonolite occurs in the northern part of the area with pseudoleucites up to 2.5 cm in diameter composed of K-feldspar and sericite, set in a groundmass of the same minerals together with biotite, garnet, epidote and sulphides. At least ten distinct syenite phases have been recognized, most of which contain K-feldspar phenocrysts and all of which are highly potassic. The 'dark syenite porphyry' is the oldest and forms a plug some 600 m in diameter as well as a nunber of dykes. This syenite is characterized by orthoclase phenocrysts up to 1.5 cm in length, and pseudoleucites up to 5 cm in diamter are found along the contacts of the plug and in one of the dykes. This rock contains >12% K2O and <1% Na2O (Allen et al., 1976, Table 1, anals 1-3).

Economic: 
Ten incompletely delineated copper deposits are known at Galore Creek, the largest being 'Central Zone', which is known to contain at least 125 million tons of ore grading 1.06% Cu, 0.40 p.p.m. Au and 7.7 p.p.m. Ag. The principal copper mineral is chalcopyrite with bornite locally abundant.
Age: 
Four K-Ar determinations on biotite gave 174-198 Ma (White et al., 1968).
References: 
ALLEN, D.G., PANTELEYER, A. and ARMSTRONG, A.T. 1976. Galore Creek. In Porphyry deposits of the Canadian Cordillera. Canadian Institute of Mining and Metallurgy, Special Volume, 15: 402-14. WHITE, W.H., HARAKAL, J.E. and CARTER, N.C. 1968. Potassium-argon ages of some ore deposits in British Columbia. Bulletin, Canadian Institute of Mining and Metallurgy, 61: 1326-34
Fig. 10 Galore Creek (after Allen et al., 1976, Fig. 2).
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith