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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  29-Sep-2011 by Laura deGroot (LDG)

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NMI 082K11 Pb5
Name SHEILA, SHELAGH, BANNOCKBURN Mining Division Slocan
BCGS Map 082K065
Status Showing NTS Map 082K11E
Latitude 050º 38' 41'' UTM 11 (NAD 83)
Longitude 117º 09' 34'' Northing 5610330
Easting 488727
Commodities Silver, Lead, Zinc Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
J01 : Polymetallic manto Ag-Pb-Zn
Tectonic Belt Omineca Terrane Ancestral North America
Capsule Geology

The Sheila prospect is at approximately 2100 metres elevation, at the head of Hall Creek, a major northeasterly flowing tributary of Duncan River. The showing is in the Bannockburn basin, area and is part of a cluster that includes the Bannockburn [082KNW051] and Superior [082KNW054]. The Red Elephant [082KNW053] is in the same area but is a different type of deposit.

Granby Consolidated Mining, Smelting and Power Company Limited discovered (or rediscovered) and explored the Sheila area in 1954 while working on the Bannockburn vein. It mapped, sampled and trenched the "Shelagh" showings and drilled eight short packsack drill holes into the "vein". Three years later, the area was mapped for Bunker Hill Co. Limited and Sheep Creek Mines Limited and the latter drilled four diamond drill holes totaling 319.6 metres. One hole was into the Bannockburn vein and the other three were into the Shelagh "vein", which is an unusual replacement deposit that has been explored over a length of approximately 1067 metres. There was no more work done until SEREM Limited drilled eleven holes, for a total of 570.9 metres, on the southwest side of Bannockburn basin in 1977. Only two of the holes produced significant results. Diamond drill hole B6 intersected 3.17 per cent lead, 0.33 per cent zinc and 16.8 grams per tonne silver over 4.02 metres (true) width. Hole B8 averaging 5.03 per cent lead, 1.03 per cent zinc and 31.54 grams per tonne silver over 0.88 metre (true) width. Several mineralized zones have been found in the limestone. The "B" zone is 110 metres long, has an average width of 2.07 metres and contains 2.81 per cent lead, 0.14 per cent zinc and 9.60 grams per tonne silver. The "C" zone is 103.6 metres long, has an average width of 1.80 metres and contains 4.2 per cent lead, 0.4 per cent zinc and 15.77 grams per tonne silver. The "D" zone is 42.7 metres long, has an average width of 2.99 metres and contains 5.5 per cent lead, 0.2 per cent zinc and 30.86 grams per tonne silver and the "E" zone is 15.24 metres long, has an average width of 3.36 metres and contains 3.23 per cent lead, 0.41 per cent zinc and 16.11 grams per tonne silver. Note none of these zones have been defined in the third dimension. However, SEREM Limited estimated the mineralized unit should contain 1135.5 tonnes per vertical metre, have a strike length of 1036 metres, an average width of 3.5 metres and grade of 6.2 percent combined lead and zinc and 24.0 grams per tonne silver (EMPR PF: Mikado Resources Limited Prospectus). The recent history of the area has followed that of the adjacent Bannockburn [082KNW051] and Superior [082KNW054] occurrences. The owners, J.A.C. Ross and Associates, incorporated Bannockburn Resources Limited to develop the area in 1981 and later optioned it to Turner Energy and Resources Limited and Mikado Resources Limited. However, they were mainly interested in the nearby Wagner [082KNW212] and Abbott [082KNW056] properties.

The Trout Lake area is underlain by a thick succession of sedimentary and volcanic rocks of the Badshot Formation and Lardeau Group near the northern end of the Kootenay arc, an arcuate, north to northwest trending belt of Paleozoic and Mesozoic strata that is now classified as a distinct, pericratonic, terrane. The arc rocks are bordered by Precambrian quartzite in the east and they young to the west, where they are bounded by Jurassic-age intrusive complexes. They were deformed during the Antler orogeny in Devonian-Mississippian time and were refolded and faulted during the Columbian orogeny, in the Middle Jurassic. A large panel, the "Selkirk allochthon", was later offset to the northeast by dip-slip motion along the Columbia River Fault.

The Badshot Formation is composed of a thick Cambrian limestone that is a distinctive marker horizon in the Trout Lake area. It is underlain by Hamill Group quartzite and it is overlain by a younger assemblage of limestone, calcareous, graphitic and siliceous argillite and siltstone, sandstone, quartzite and conglomerate, and also mafic volcanic flows, tuffs and breccias, all of which belong to the Lardeau Group. The rocks are isoclinally folded and intensely deformed, but only weakly metamorphosed. They occur as intercalated beds of marble, quartzite and grey, green and black phyllite and schist. Fyles and Eastwood (EMPR BULL 45) subdivided the group into six formations (Index, Triune, Ajax, Sharon Creek, Jowett and Broadview) of which the lowermost (Index) and uppermost (Broadview) are the most widespread. The Triune (siliceous argillite), Ajax (quartzite) and Sharon Creek (siliceous argillite) are restricted to the Trout Lake area. The Jowett is a mafic volcanic unit.

Sheila prospect is approximately 183 metres to the southwest and several hundred metres above the Bannockburn vein, which is higher in grade and received much of the early attention. Although the showings were originally described as veins, they are replacement deposits in calcareous quartzite of the Marsh Adams Formation, near the top of the Hamill Group. The Marsh Adams quartzite becomes increasingly argillaceous and micaceous up section but contains a pronounced, 6.1 to 30.5 metres thick, belt of rusty weathering quartzite approximately 3.0 metres below the base of the overlying Badshot Formation. This unit contains lenses of coarse-grained quartzite in which, visible rounded, opalescent grains of quartz are cemented by carbonate and, locally, galena. The mineralized quartzite is overlain by calcareous "siltite" (fine-grained quartzite) or phyllite which defines the very top of the formation. The productive unit is approximately 12.2 metres thick; however, it is not uniformly mineralized. The best values are found in the upper part, where the quartzite is coarse-grained. In places the quartzite is a quartzose limestone in which grains of quartz float in calcite. Finer-grained quartzites are generally more tightly packed and have less room for calcite and galena. The mineralized sections range from 0.61 to 3.6 metres in thickness and contain fine-grained, disseminated sulphides, mainly galena, minor pyrite and sphalerite with small amounts of chalcopyrite and possibly tetrahedrite (EMPR ASS RPT 6729, 12873).

The rocks immediately below the mineralized section are less well mineralized but are cut by galena-bearing quartz veinlets. The quartzites adjacent to these veinlets may contain a small amount of disseminated, replacement sulphide. In the footwall area, there is a spatial relationship between quartz vein density and grade in the adjacent quartzite. Near the showings, the rocks dip steeply to form a tightly overturned anticline with a shallow plunge. The axial plane of the (Marsh Adams) anticline dips steeply to the northeast and lies between the Sheila and Bannockburn prospects. The replacement mineralization is located on the crest and in the southwest limb of the fold. The northeast limb is barren. The quartzite in the southwest limb is cut and displaced by a series of vertical faults that down-throw it 15.24 to 24.38 metres on the northwest side. These faults appear to have remobilized and redistributed some of the sulphide. The principal controls on mineralization on the property appear to be (1) the Marsh Adams Anticline, (2) appropriate calcareous lithologies in the quartzite and (3) later faults which caused redistribution of sulphide.

In 1984, the British Columbia Ministry of Energy and Mines Reserve Map indicated a resource of 2.7 million tonnes grading 4 per cent combined lead and zinc.

EMPR AR 1960-78,79
EMPR ASS RPT *6729, *12873
EMPR EXPL 1978-E82
EMPR OF 1990-24
EMPR Reserve Map, 1984
EMPR PF (Mikado Resources Limited Prospectus and news release folder)
GSC MEM 161 pp. 77,78,82
EMPR PFD 20542