The Bronson occurrence is located approximately 7 kilometres north of the Gataga River, 14 kilometres southwest of Churchill Peak in the mountainous Muskwa Ranges of the Northern Rocky Mountains and approximately 169 kilometres west-southwest of Fort Nelson (Assessment Report 2487, Map 3).
The occurrence 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; 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. Crosscutting 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, located on the 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-northeast (the eastern end is known as the 'East' zone) and for approximately 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 (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 greater than 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, located on the 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).
Work History
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, totalling 762 metres and 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 1981 and 1982, Coppex Syndicate completed a program of geological mapping and geochemical (rock and soil) sampling on the area as the BE and MO claim groups.
In 2005, Twenty-Seven Capital Corp. completed a regionally extensive program of geochemical (rock, silt and soil) sampling and a 9002.0 line-kilometre airborne magnetic survey on the area as the Muskwa property. Three outcrop samples (B374304 through B374306) of mineralized quartz-carbonate veins from the West zone area yielded from 0.51 to 19.95 per cent copper with up to 13.4 grams per tonne silver and greater than 1.00 per cent zinc and (Assessment Report 38212).
In 2012, a remote sensing and geophysical data interpretation program was completed on the area as a part of the regionally extensive Northern IOCG property. In 2019, High Range Exploration Ltd. completed a minor program of rock sampling, GIS compilation and application of remote sensing on the area as the Bronson property.
In 2018, Fabled Copper Corp. completed a minor program of geological mapping, rock sampling and petrographic analysis on the Toro property.
In 2020, Fabled Copper Corp. completed a minor program of rock sampling and historical data review on the area as the Bronson property. The following year, a program of photogeological interpretation, rock sampling and 1.6 line-kilometres of combined airborne magnetic and ground electromagnetic (VLF) surveys were completed on the property. Two highly mineralized float samples (D723404 and D723398) were collected downslope to the north of the adit and yielded 8.17 and 23.1 per cent copper, respectively, with up to 36.5 grams per tonne silver (Assessment Report 39912).
