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File Created: 09-Sep-1987 by Jim M. Britton (JMB)
Last Edit:  24-Mar-2022 by Nicole Barlow (NB)

Summary Help Help

NMI
Name COOGAN'S BLUFF (SULPHURETS), KRUCHKOWSKI Mining Division Skeena
BCGS Map 104B050
Status Prospect NTS Map 104B08E
Latitude 056º 28' 30'' UTM 09 (NAD 83)
Longitude 130º 11' 28'' Northing 6259584
Easting 426629
Commodities Gold, Silver, Copper, Lead, Zinc Deposit Types H04 : Epithermal Au-Ag-Cu: high sulphidation
Tectonic Belt Intermontane Terrane Stikine
Capsule Geology

The Coogan's Bluff zone appears to be the same as the original Kruchkowski showing which consisted of a stockwork of quartz veins up to 5 centimetres thick, exposed over an area of a few square metres, cutting sericite altered rocks. Veins carry thin seams of pyrite, tetrahedrite and arsenopyrite. Hostrock lithology has been obscured by intense alteration and shearing. Fifty metres to the south of the veins are foliated andesitic lapilli tuffs which are probably also the hostrock type. The showing has been trenched by Esso Minerals Ltd. (trench number T76 and T79) in 1980 or 1981 but no assay data has been reported. The Kruchkowski showing is located about 400 metres northwest of Brucejack Lake (Open File 1988-4). Small exploration pits and trenches were blasted and excavated by hand. The showing was visited by Ministry of Energy, Mines and Petroleum Resources Geological Survey Branch geologist J.M. Britton in 1987.

The showing occurs in volcanic and sedimentary rocks of the Upper Triassic-Middle Jurassic Hazelton Group assigned to the top of the Unuk River Formation of Hettangian to Pliensbachian age. These rocks have been variably folded, hydrothermally altered, sheared and cut by minor faults.

Work in 1994 by Newhawk Gold Mines Ltd. outlined a 100 by 150 metre northwest trending zone of discontinuous sheeted quartz veins up to 50 metres long and 1 metre wide, lying along strike to the northwest, of the Shore zone (104B 189). The zone may represent the strike extension of the Shore zone.

Drillhole S94-451 was designed to intersect the Coogan's Bluff zone approximately 130 metres below surface. The hole intersected several zones of quartz +/- carbonate stockwork and numerous discrete, narrow quartz veins hosted within fine grained, massive feldspar-hornblende phyric andesite flows and andesitic lapilli tuff. Hostrocks are variably sericite +/- carbonate altered, but rarely silicified, and typically carry 5-6 per cent disseminated pyrite. Four main stockwork zones were intersected; at 52.2 to 54.5 metres, 63.0 to 65.5 metres, 108.0 to 113.9 metres, and 180.9 to 213.0 metres, which coincide with diffuse zones of stockwork mapped at surface. These intersections confirm a steep (65 to 80 degree) zone dip to the southwest. The zones contain 20 to 70 per cent massive white to pale grey quartz +/- carbonate +/- barite veins ranging in width from several millimetres to 80 centimetres, and carry trace to 2 per cent pyrite and rare tetrahedrite and sphalerite. The best mineralization consists of 2 per cent sphalerite, trace tetrahedrite and less than 1 per cent galena within a strong quartz stockwork at 32.2 to 32.9 metres, but gold assays from this section are only weakly anomalous.

Drilling indicates that the nature of the Coogan's Bluff zone does not change significantly with depth, but remains a series of subparallel stockwork zones to at least 200 metres below surface. Although one significant intersection (9.7 grams per tonne gold and 70.2 grams per tonne silver across 0.9 metre) was made in the main stockwork zone, the zone lacks potential to host significant volume of ore grade material (Assessment Report 24610).

Bibliography
EMPR ASS RPT 6255, 9435, 10260, *24610, 36214, 39314
EMPR BULL 63
EMPR EXPL 1976-E181; 1977-E222; 1980-464; 1981-248; 1982-382; 1983-520; 1986-C441
EMPR FIELDWORK 1982, p. 171; 1987, p. 199
EMPR OF 1988-4
EMPR PF (Bridge, D.A., Ferguson, L.J. and Brown, M.G. (1981): 1980 Exploration Report on the Sulphurets Property by Esso Minerals Canada Ltd. (unpublished); Bridge, D. and Melnyk, W. (1982): 1981 Exploration Report on the Sulphurets Property by Esso Minerals Canada Ltd. (unpublished); Bridge, D. and Melnyk, W. (1983): 1982 Exploration Report on the Sulphurets Property by Esso Minerals Canada Ltd. (unpublished); Britten, R.M. (1983): Regional Geological Assessment of the Stewart-Sulphurets Area, and Geology and Alteration of the Sulphurets Prospect Area by Esso Minerals Canada Ltd. (unpublished); Lomenda, M.G. (1983): Geology, Alteration and Mineralization of the Mitchell-Sulphurets Ridge and Snowfields Gold zone, Sulphurets Property by Esso Minerals Canada Ltd. (unpublished); Melnyk, W. (1983): 1983 Exploration Report on the Sulphurets Property; Geology Map - 1:31,250 Scale - Newmont Exploration of Canada Ltd., 1960s)
GSC P 89-1E, pp. 145-154
Kirkham, R.V. (1963): M.Sc. Thesis, U.B.C.: The Geology and Mineral Deposits in the Vicinity of the Mitchell and Sulphurets Glaciers
Simpson, T.M. (1983): The Geology and Hydrothermal Alteration of the Sulphurets Deposits, Northwest British Columbia, M.Sc. Thesis, University of Idaho
Armstrong, T.A. (2010-01-14): Technical Report and Resource Estimates on the West, Bridge, Galena Hill, Shore, SG & Gossan Hill Gold & Silver Zones of the Brucejack Property
Ghaffari, H. (2010-09-10): Technical Report and Preliminary Assessment of the Snowfield-Brucejack Project
Ghaffari, H. (2010-10-28): Technical Report and Preliminary Assessment of the Snowfield-Brucejack Project
Armstrong, T.A. (2011-03-04): Technical Report and Updated Resource Estimate on the Brucejack Property
Armstrong, T.A. (2011-04-04): Technical Report and Updated Resource Estimate on the Snowfield-Brucejack Property
Ghaffari, H. (2011-06-03): Technical Report and Preliminary Economic Assessment of the Brucejack Project
Armstrong, T.A. (2012-01-12): Technical Report and Resource Estimate on the Brucejack Property
Ghaffari, H. (2012-02-20): Technical Report and Updated Preliminary Economic Assessment of the Brucejack Project
Jones, I. (2019-04-04): Technical Report on the Brucejack Gold Mine
Pretium Resources Inc. (2020-03-09): Technical Report on the Brucejack Gold Mine, Northwest British Columbia

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