Type Locality:

Dismal Lakes area, District of Mackenzie, 67 deg 26'N, 117 deg 00'W.

Distribution:

1,980 m (6,500 ft). Dismal Lakes area, District of Mackenzie.

Locality Data:

Thickness(m): Maximum 1980.

Lithology:

Consists of buff to white, mainly thick-bedded and medium- to coarse-grained sandstone and intercalated black shale, tan weathering dolomite and red sandstone, laminated dolomite , massive dolomite followed by laminated dolomite. This group is composed of five distinct lithologic units. In ascending order they are: 1) medium- to fine-grained massive to finely laminated buff to white quartzose sandstones containing rare quartz-pebble layers; in the upper part there is a distinctive white sandstone rhythmically intercalated with black carbonaceous shales with dessication cracks and ripple marks; 2) red mudstones overlain by tan-weathering dolomites; ripple marks, desiccation cracks and small scale crossbedding, halite casts and pseudomorphs after gypsum are common; 3) intraformational conglomerates, oolites, oncolites and stromatolites, rare beds of shale and beds that contain "molar tooth structure" form distinctive markers, chert nodules present; 4) thick-bedded units with distinctive conical stromatolites, domal and bulbous forms also occur; and 5) intraformational conglomerates, oolites, oncolites, stromatolites, ripple marks, cross beds and dessication structures common. Chert nodule zones and black shale beds also present.

Relationship:

Unconformably overlies the Hornby Bay Group and is conformably overlain by the Coppermine River Group. Internally the units are conformable.

References:

Baragar, W.R.A. and Donaldson, J.A., 1973. Coppermine and Dismal Lakes map-areas (Report and Maps 1337A and 1338A); Geological Survey of Canada, Paper 71-39, 20 p. + "A" Series Map 1337A, Geology, Coppermine, District of Mackenzie, Scale: 1:250 000, NTS 86-O and "A" Series Map 1338A, Geology, Dismal Lakes, District of Mackenzie, Scale: 1:250 000, NTS 86-N.