Type Locality:

No specific locality designated, but the unit is well exposed in the Limestone Mountain area, at Nordegg, Cadomin, and in the Snake Indian River valley, Alberta.

Distribution:

Known in outcrop from Limestone Mountain area, south of Clearwater River, north to the Peace River area, varying from 15 to 47.8 m (49 to 157 ft) in thickness. According to Springer et al. (1964), in the subsurface it extends eastward to a line from Pincher Creek through Calgary to the Gilbey area southwest of Edmonton and consists of speckled dark brown shale of bituminous appearance, with thin beds of shaly limestone.

Lithology:

Dark grey to black, hard, platy to medium-bedded, cherty and phosphate limestones, with 40-90% chert occurring as layers exhibiting pinch and swell, lenticular beds and nodules; chert dark grey to black with blue tints. Interbeds of platy, dark grey and black silty shales and papery black shales also present in small amounts. A thin (30 cm, 12 in) band of slightly phosphate chert conglomerate often forms the lowermost bed of this unit. In the Limestone Mountain area Ollerenshaw (1966) recognized three subdivisions: a basal soft, brown shale up to 0.9 m (3 ft) thick, a middle chert and limestone from 7.0 to 24.7 m (23 to 81 ft) thick, and an upper platy, oolitic and silty limestone, 6.7 to 7.6 m (22 to 25 ft) in thickness. This upper unit is now referred to the Red Deer Member (q.v.). The Nordegg Member is usually capped by the highly fossiliferous Oxytoma Bed, which should be included within this member.

Relationship:

Where present represents the base of the Fernie Formation, resting on the Triassic Spray River Group (infilling cracks in its upper surface) or directly on Paleozoic units with apparent conformity. In most exposures the top of the member is marked by the highly fossiliferous Oxytoma Bed which is conformably overlain by black, fissile shales of the Poker Chip Shale. Rocks of equivalent age farther north and south are dark, indurated shales, phosphatic limestones and sandstones; these rocks have never been formally designated as a member within the Fernie Formation.

History:

Originally referred to as the "black chert member" by Warren (1964) and Spivak (1949); the latter noted use of the term Nordegg Member.

Other Citations:

Frebold, 1957, 1969; Ollerenshaw, 1968; Springer et al., 1964; Spivak, 1949; Stott, 1967, Warren, 1934.

References:

Spivak, Joseph, 1949. Jurassic sections in foothills of Alberta and northeastern British Columbia; America Association of Petroleum Geologists (AAPG), AAPG Bulletin, vol. 33, no. 4 (April), pp. 533-546.