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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  30-Jan-2018 by George Owsiacki (GO)

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NMI 094K3 Cu5
Name BRONSON, BRON, BE, MUSKWA Mining Division Liard
BCGS Map 094K014
Status Prospect NTS Map 094K03W
Latitude 058º 11' 06'' UTM 10 (NAD 83)
Longitude 125º 18' 22'' Northing 6451626
Easting 364408
Commodities Copper, Silver, Gold Deposit Types I06 : Cu+/-Ag quartz veins
Tectonic Belt Foreland Terrane Ancestral North America
Capsule Geology

The Bronson occurrence is located 7 kilometres north of the Gataga River, 14 kilometres southwest of Churchill Peak in the mountainous Muskwa Ranges of the Northern Rocky Mountains, approximately 169 kilometres west-southwest of Fort Nelson (Assessment Report 2487, Map 3).

The showing is in a region known as the Muskwa Anticlinorium, a major north-northwest trending structure characterized by thrust faults and moderate folding. Rocks as old as Middle Proterozoic (Helikian) outcrop in the structure, along with Paleozoic rocks (Geological Survey of Canada Map 1343A; Geological Society of America, Geology of North America, Volume G-2, page 639). All belong to Ancestral North America (Geological Survey of Canada Map 1713A). The Middle Proterozoic rocks are pre-Windermere Supergroup, and are known as the Muskwa Assemblage (Geological Society of America, Geology of North America, Volume G-2, page 111).

Northeast to (more commonly) north-northwest trending, steeply dipping diabase or gabbroic dikes are common in the region. These Proterozoic intrusions were structurally controlled as their presence and orientation are closely related to regionally important fault and fracture zones in the Proterozoic sedimentary rocks.

The Bronson claim group is underlain mainly by the Aida and Gataga formations of the Muskwa Assemblage. The Aida Formation comprises mainly dolomitic mudstone and siltstone, and argillaceous limestone. The overlying Gataga Formation, outcropping to the west, consists of slaty mudstone and siltstone (Geological Survey of Canada Memoir 373, Paper 67-68; Assessment Reports 2487, 10960). In the extreme west are shale, argillite and limestone of the Cambrian Atan Group (Assessment Report 2487).

The Bronson prospect lies on an east-trending ridge composed of slate and limy argillite, probably of the Gataga Formation. These rocks strike north-northwest and dip 35 to 60 degrees west. Several large diabase dikes, 15 to 150 metres thick, outcrop on the ridge. They strike northeast to northwest and dip steeply westward. Cross-cutting dikes are common. The sedimentary rocks hosting the mineralization are intensely and complexly fractured. The main fractures and the most important quartz-carbonate veins within them strike 060 degrees and dip vertically to steeply northwest, some of them cutting across the dikes as well.

There are two particular areas of such veining: one is on the steep, north-facing side of the ridge, and the other is a few hundred metres to the south, on the southeast-facing slope (Assessment Report 2487; Geology, Exploration and Mining in British Columbia 1971). The northern or 'Central' zone, on Bronson 19 and 6 claims and on which the occurrence is centred, consists of several parallel veins in a zone up to 50 metres wide and traceable for over 600 metres east-northeastwards (the eastern end is known as the 'East' zone) and for about 360 metres down the cliff face. Much of this zone consists of quartz-sericite phyllite hosting numerous quartz veinlets. The veins and veinlets are rich in chalcopyrite, though mineralization is irregular. The better results are found at the western end. One 1.5-metre chip sample (sample 418) assayed 17.69 per cent copper and 4.8 grams per tonne silver (Assessment Report 2487). Most of the other chip samples from this cluster of veins assayed over 6 per cent copper. Some of the veins were grouped to produce a weighted average grade of 2.7 per cent copper over a total width of 33.5 metres (Assessment Report 2487, page 14).

The other zone or 'South' zone, on Bronson 21 claim, contains three veins from 0.3 to 1.2 metres in width, heavily mineralized with bornite and chalcopyrite, in a zone 36 metres wide. The longest vein has been traced for 180 metres, along the sheared margins of a branching dike trending 020 degrees. Copper values are generally higher than the Central zone but apparently over narrower widths. A chip sample (403) assayed 29.22 per cent copper and 116 grams per tonne silver over 0.45 metre (Assessment Report 2487). Another sample (402) assayed 5.8 grams per tonne gold (Assessment Report 2487). A younger variety of mineralization is represented by vuggy quartz veinlets with chalcopyrite and specular hematite.

There is also a 'West' zone, an isolated area 450 metres west of the Central zone. Quartz-carbonate veins are mineralized with chalcopyrite and bornite, and yield assays that average 7.88 per cent copper over 1.7 metres. Linked with the Central and East zones, this belt of intermittent, fracture-controlled mineralization has an overall length of at least 1.1 kilometres (Geology, Exploration and Mining in British Columbia 1971).

During the 1970 field season, Canadian Superior Exploration Limited geologically mapped the claims and five veins, and collected rock samples. A short adit (22 metres) was driven on the north slope of Bronson Mountain at an elevation of 2089 metres, and from this location three diamond-drill holes (762 metres total) inclined at 5, 24, and 30 degrees above the horizontal, were drilled to test at depth the continuity of the Central zone. This work proved to be difficult and very costly, and the results were disappointing. During the 1971 field season, a second drill site was selected on the south face of the mountain at an elevation of 2249 metres, and from it four diamond-drill holes, three dipping at approximately at 10 degrees and one at 30 degrees, were drilled to intersect the Central zone at depth. The results of this program were also disappointing and indicated that neither the numerous veins of the Central zone nor the mineralization continue at depth for any significant distance. Four surface diamond-drill holes totalling 1379.5 metres were also completed on the Bron 19 and 170 claims (Geology, Exploration and Mining in British Columbia 1971).

In 2005, Twenty-Seven Capital Corp. staked 400 claims and optioned two properties that are surrounded by its claims. The combined land package encompasses about 475 square kilometres and cover a number of mineral showings including two prospects that have received advanced exploration. The recently staked claims (Muskwa property) are wholly owned by Twenty-Seven Capital, without underlying interests. The agreement for the optioned Bronson (094K 027, this description) and Toro (094K 050) properties was signed with an arm's-length individual.

EMPR GEM 1970-46; *1971-75,97-99
EMPR EXPL 1982-348
EMPR ASS RPT *2487, 10960, *33336
GSC P 67-68
GSC MAP 1343A; 1713A
GSA (Gabrielse, H. and Yorath, C.J. (Eds.) (1991): Geology of North America, Volume G-2).
N MINER June 11, 1970
PR REL Twenty-Seven Capital Corp., Apr.13, 2005