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File Created: 17-Aug-1995 by Gilles J. Arseneau (GJA)
Last Edit:  04-Sep-1995 by Gilles J. Arseneau (GJA)

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Name ECHO LAKE Mining Division Golden
BCGS Map 082K009
Status Showing NTS Map 082K01E
Latitude 050º 01' 05'' UTM 11 (NAD 83)
Longitude 116º 12' 21'' Northing 5540940
Easting 556894
Commodities Tungsten, Zinc, Lead Deposit Types I12 : W veins
Tectonic Belt Omineca Terrane Ancestral North America
Capsule Geology

The Echo Lake occurrence is located 3 kilometres south of Doctor Peak of the Purcell Mountain Range, on a small ridge near a tarn locally known as Echo Lake at the headwaters of east Doctor Creek.

The occurrence is hosted within a small gabbroic dike that cuts the Lower Aldridge Formation of the Proterozoic Purcell Supergroup.

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 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 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 Proterozoic 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 mainly 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 Lower Aldridge sedimentary rocks (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 scheelite, sphalerite and minor galena in a narrow muscovite-tourmaline-actinolite vein cutting the gabbroic sill on the west ridge above Echo Lake. The mineralization is erratic and uneconomic. Geological mapping in 1971 and 1973 failed to outline any significant reserves (Assessment Report 3287).

EM EXPL 2000-43-53
EM GEOS MAP 1998-4
EMPR ASS RPT 3287, 4705, *6413, 11737
EMPR FIELDWORK 1989, pp. 29-37
EMPR GEM 1971-420
EMPR PF (82KSE General File - Geology map by P. Billingsley, 1958)
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