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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  26-Mar-2012 by Karl A. Flower (KAF)

Summary Help Help

BCGS Map 082K010
Status Prospect NTS Map 082K01E
Latitude 050º 00' 46'' UTM 11 (NAD 83)
Longitude 116º 10' 17'' Northing 5540380
Easting 559368
Commodities Silver, Zinc, Lead, Copper Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Omineca Terrane Ancestral North America
Capsule Geology

The Silver Key property is situated 4.5 kilometres southeast of Doctor Peak of the Purcell Mountain Range, at the headwaters of the east fork of Doctor Creek, a south tributary of Findlay Creek (Minister of Mines Annual Report 1935).

The occurrence is hosted within the lower division of the Aldridge Formation of the Proterozoic Purcell Supergroup of southeastern British Columbia.

In the vicinity of the occurrence, the Aldridge Formation consists of quartz wacke, quartz arenite, siltstone and lesser argillite that are intruded by thick gabbroic sills of the Proterozoic Moyie intrusions. The sedimentary rocks are characteristically rusty weathering, fine to medium grained and thin to medium bedded. Individual beds range from a few millimetres to 30 centimetres thick. Discontinuous horizons of intraformational conglomerate were noted in a number of localities. Finely disseminated pyrrhotite is common. The sedimentary rocks of the Lower Aldridge Formation have undergone both thermal and regional metamorphism to at least greenschist facies. Biotite alteration in the argillaceous units and quartz-sericite alteration in the arenite and wacke have generated widespread phyllitic and schistose textures.

The Moyie sills cutting the Lower Aldridge Formation are sill-like in overall form but often crosscut bedding or appear as irregular lenses. Some are in excess of 100 metres thick and can be traced almost 10 kilometres. The thicker sills have coarse grained gabbroic cores and finer dioritic margins. They are all primarily composed of hornblende and plagioclase phenocrysts set in a matrix of similar composition (Paper 1990-1).

The White Creek batholith is a well-differentiated Cretaceous granitic intrusion which cuts the Lower Aldridge rocks just southeast of the mineral occurrence. Along the northern border of the batholith, a megacrystic granodiorite phase is common. Plagioclase phenocrysts are commonly 3 to 5 centimetres long, set in a matrix of fine to medium-grained plagioclase, potassium feldspar, quartz and biotite. Magnetite and pyrite occur locally. Aplite and pegmatite dikes are common within the sedimentary rocks of the Lower Aldridge Formation (Geological Survey of Canada Memoir 369).

On the property, the Purcell sedimentary rocks strike 060 degrees and dip gently (25 degrees) northwest. Deformation of the strata is minimal but minor northwest trending symmetrical folds have been documented.

The occurrence consists of several opencuts and a small adit 130 metres long. Mineralization consists of disseminated galena and pyrite within structurally controlled quartz veins 2 to 5 centimetres wide that strike due north and dip 45 degrees west. The veins are within tightly folded and sheared quartzite. At least six veins are known to exist. A 1.2 metre wide chip sample taken across one of the exposed veins in the trenches assayed 14 grams per tonne silver and 0.6 per cent lead (Minister of Mines Annual Report 1938). In 1995, grab sampling returned 763.5 grams per tonne silver and 1.82 per cent lead (Assessment Report 24380).

The prospect is very close to the edge of the White Creek batholith, however, the relationship to the intrusion is unknown.

EMPR AR 1931-E11; 1934-E28; 1935-E11; *1938-E28; 1958-52; 1939-38; 1940-27
EMPR ASS RPT 6413, 24380
EMPR EXPL 2000-43-53
EMPR FIELDWORK 1989, pp. 29-37
EMPR GEOS MAP 1995-1; 1998-4
EMPR OF 1990-20; 1990-26
EMPR PF (Sketch map; 82KSE General File - Geology map by P. Billingsley, 1958)
GSC MAP 1326A; 1712A; 1713A
Pope, A.J. (1989): The Tectonics and Mineralization of the Toby-Horsethief Creek Area, Purcell Mountains, Southeast British Columbia, Canada, unpublished Ph.D. Thesis, University of London, England