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File Created: 15-Feb-1988 by Gordon S. Archer (GSA)
Last Edit:  27-Mar-2022 by Nicole Barlow (NB)

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NMI 104B1 Au1
BCGS Map 104B010
Status Past Producer NTS Map 104B01E
Latitude 056º 03' 43'' UTM 09 (NAD 83)
Longitude 130º 00' 20'' Northing 6213430
Easting 437387
Commodities Gold, Silver, Zinc, Lead, Copper Deposit Types I02 : Intrusion-related Au pyrrhotite veins
G07 : Subaqueous hot spring Ag-Au
Tectonic Belt Intermontane Terrane Stikine
Capsule Geology

The Sebakwe orebody, part of the Silbak Premier mine (104B 054), is located 250 metres north and slightly east of the B.C. Silver orebodies (104B 155) 22 kilometres north of the community of Stewart. Mineralization was first discovered as silver-bearing stringers in tuffs and the orebody was intersected 300 metres along a tunnel driven from the east fork of Cooper Creek in 1926. The property along with the B.C. Silver Mines holdings and the Premier mine was amalgamated into British Silbak Premier in 1935. For a more extensive capsule geology and bibliography refer to the Silbak Premier mine (104B 054).

Located in the Intermontane Belt, the area, bounded on the west by the Coast Belt and on the east by the Bowser Basin, is underlain by the volcanic arc assemblage of the Stikine Terrane.

The deposit is hosted in Upper Triassic to Lower Jurassic Hazelton Group, Unuk River Formation. The Hazelton Group is a northwest-trending belt of folded metavolcanic rocks containing a thick sequence of argillites and siltstones infolded along a synclinal axis. The Sebakwe deposit is a blind orebody capped by barren maroon tuffs.

The ore is hosted by massive andesite, andesite breccia and lapilli tuff intruded by Early Jurassic Texas Creek plutonic suite dacitic porphyry dike. The andesite, at least 750 metres thick, is unconformably overlain by volcaniclastic and epiclastic rocks. Potassium feldspar porphyry (historically known as the "Premier Porphyry") is spatially associated with the ore, this relationship is thought to indicate a Lower Jurassic mineralization age.

The Sebakwe deposit is the northerly continuation of the steeply northwest dipping, "Main" or "Northeast" zone of the main Premier and B.C. Silver deposits. This trend is believed to represent structural control on the mineralization and emplacement of dacite porphyry intrusions. The ore is predominantly discordant but locally concordant with the moderately northwest dipping andesite flows, breccias and dacite flows. The initial discovery was 76.2 metres long, 4.6 metres wide, striking northeast, plunging steeply southwest and dipping 45 degrees northwest.

There are at least four styles of mineralization with textures ranging from stockwork and siliceous breccia to locally layered and massive sulphide-rich mineralization.

Hydrothermal alteration zones related to the mineralizing system are represented by a proximal silicification/quartz stockwork and potassium feldspar and/or sericite facies potassic alteration. Peripheral to mineralization is a propylitic alteration assemblage of carbonate, chlorite and pyrite. The variable intensity and type of alteration is partially controlled by fracture intensity and host lithology, and presumably, elevation in the hydrothermal system.

Ore minerals include pyrite, sphalerite, galena, with minor tetrahedrite, chalcopyrite, arsenopyrite and local pyrrhotite. Bonanza ore contains native gold, electrum, pyrargyrite, polybasite, argentite and native silver. Gangue minerals are quartz, potassium feldspar, chlorite, carbonate and others. Sulphide content varies, generally less than 5 per cent but can be as high as 75 per cent.

The diversity of the ore is an indication of the complex and episodic nature of ore deposition. A hybrid ore genesis model combining epigenetic vein and porphyry copper characteristics compare well with the features observed.

Post-1935 production data is included in the production figures for the Silbak Premier mine (104B 054).

Diamond drilling in 1994 was performed in an area located north of Lesley Creek (Cooper Creek on some maps), west of the Long Lake-Fish Creek fault, east of Cascade Creek and bounded to the north by a dike or stock of "Premier Porphyry" along the Big Missouri road north of the switchbacks. Geologically, two main features were discovered which were previously unknown. The first was the discovery of arsenopyrite-rich veins with or without sphalerite, galena and chalcopyrite that contain occasional grains of visible gold. Silver to gold ratios are from 3:1 to 1:3. Veins of this mineralogy are at best rare in the Stewart camp. Lead isotopic analyses of galena from one of these veins from drillhole P94CH725 suggests the mineralization is Tertiary, not Jurassic in age (Assessment Report 24622). The second feature is that the favourable stratigraphy undergoes a marked change near P94CH725 but does continue to the north of the interpreted sub-basin boundary. The most significant intersection from the drilling is 6.3 metres of 4.05 grams per tonne gold in drillhole 94-725 (Assessment Report 24622).

In 2014, a total of 2 diamond-drill holes were completed on the Sebakwe zone. Only one of the two holes successfully reached the target depth while the other one was abandoned due to the presence of an overlying waste dump. The completed hole collared into the latite/dacite flow for about 110 metres and then entered a 25-metre-thick package belonging to the Betty Creek Formation before reaching the Andesite and the Premier Porphyry. The mineralized zone is hosted by mainly QSP (quartz-sericite-pyrite) to Potassic altered Premier Porphyry with 2 to 3 per cent pyrite and 0.5 to 2 per cent sphalerite/galena and trace sulphosalts. In general, the Sebakwe (104B 153) has higher silver:gold ratios relative to the Northern Lights (104B 053), the Premier mine (West and Main zones. Hole P14-677 on the Sebakwe intersected 30.48 metres (from 30.02 to 160.50 metres) grading 0.38 gram per tonne gold and 37.9 grams per tonne silver, including 5.63 metres (from 143.54 to 149.17 metres) grading 0.71 gram per tonne gold and 59.9 grams per tonne silver (Assessment Report 35410, pages 63-65).

Ascot Resources took control of the Premier-Big Missouri project in 2007 and started an intensive exploration program and collation of all work toward a GIS database of 4,453 historic holes of the Premier Mine area which comprises six major zones: Premier (including the Premier West zone the Premier Main zone), Northern Lights zone, BC Silver zone, Sebakwe zone, and Hope and Power zones. Ascot was able to demonstrate the continuity and the linkage between all six zones with targets still open for exploration in multiple directions.

Refer to Silbak Premier (104B 054) for a broader discussion of geological information and more complete bibliography of the Premier Mine area.

EMPR AR 1916-K86; 1918-K81; 1919-N75-77; 1920-N66; 1922-N83; 1923-A81; 1925-A98; 1926-A98; 1927-C98; 1928-112; 1929-C106; 1930-A111; 1934-B25; 1935-26,27B; 1936-57; 1937-B41
EMPR ASS RPT 21993, 23073, 24622, 31489, 32357, 33267, *35410, 38850, 39342
EMPR BULL *58, pp. 153-162; 63, pp. 119-212
EMPR EXPL 1980-459
EMPR FIELDWORK 1982, pp. 183-195; 1983, pp. 149-165; 1984, pp. 316-342; 1985, pp. 217-219; 1986, pp.81-102; 1987, pp. 211-216,349-352,489-493
EMPR OF *1987-22
EMPR PF (For an extensive bibliography on the Silbak Premier mine, see 104B 054)
GSC BULL 5, pp. 24,25
GSC MEM *175, p. 168
GSC P 89-1E, pp. 145-154
GSC SUM RPT 1919, Part B, pp. 10,11B
PR REL Ascot Resources, Oct.14, 2014; Nov.7, 2016; Aug.21, Sep.8, 2017
*Brown, D.A. (1987): Geological Setting of the Volcanic-Hosted Silbak Premier Mine, Northwestern British Columbia, M.Sc. Thesis, University of British Columbia (in Property File: 104B 054)
Christopher, P.A. (2009-08-03): Technical Report on the Premier Gold Project
Kirkham, G. (2012-06-18): Technical Report on the Resource Estimate for the Premier Gold Property
Kirkham, G. (2012-08-20): Revised Technical Report on the Resource Estimate for the Premier Gold Property
Puritch, E. (2013-03-27): Technical Report and Resource Estimate for the Big Missouri and Martha Ellen Deposits, Premier Gold Property
Rennie, D.W. (2018-06-22): Technical Report on the Premier-Dilworth Project
Rennie, D.W. (2019-01-17): Technical Report on the Premier Project
Bird, S.C., Meintjes, T. (2020-02-28): Resource Estimate Update for the Premier Gold Project, Stewart, British Columbia, Canada
Ascot Resources Limited (2020-05-22): Premier & Red Mountain Gold Project Feasibility Study NI 43-101 Technical Report, British Columbia