Type Locality:

The Cushing Creek area of the McBride (93H) map-sheet, British Columbia has the most complete known section of the Miette Group; it was described in detail by Carey and Simony (1985).

Distribution:

The Miette Group is restricted to the Rocky Mountain belt, where it crops out from Lake Louise, Alberta northwestward to near Prince George, British Columbia. Thicknesses vary considerably, both regionally and locally; the lower Miette is a minimum of about 1,000 m (3,280 ft) (380 m, 1,246 ft of structural thickness is exposed at the reference section), the middle Miette varies from 2,300 to 3,000 m (7,544 to 9,840 ft) (2,785 m, 9,135 ft at the reference section), and the upper Miette varies from 700 to about 1,800 m (2,296 to 5,904 ft) (1,800 m, 5,904 ft of structural thickness at the reference section).

Lithology:

The lower, middle and upper Miette comprise a conformable sequence. The lower Miette consists of dark grey to black silty phyllite, phyllitic schist and schist, with interspersed units of light brown to tan quartzite and feldspathic quartzite, and tongues of black carbonaceous micritic limestone. The middle Miette is typified by massive to graded, thick-bedded, feldspathic, turbiditic sandstones and conglomeratic sandstones, with intervening units of grey-green to emerald green phyllite, and lesser black petite map units. A conspicuous triad marker unit of pelite and carbonate. The Old Fort Point Formation divides the middle Miette into three parts. The upper Miette consists of brownish phyllite and slate, with black micritic limestone, calcareous phyllite, sandstone and quartz sandstone. Didymaulichnus miettensis has been reported in the upper 350 m (1148 ft) of the upper Miette in the northeastern part of the McBride map-area.

Relationship:

The Miette Group belongs to the Windemere Supergroup. The lower Miette strata overlay early Proterozoic basement gneisses along a sheared unconformity on the western edge of the Rocky Mountain belt. The upper part of the middle Miette thins and fines to the east, where it interfingers with slates of the upper Miette. The upper Miette is unconformably (locally with angularity) overlain by the McNaughton Formation. The middle Miette is correlative with the middle and upper Kaza Groups of the Cariboo Mountains to the west of the southern Rocky Mountain trench. The upper Miette is correlative with the black slates and phyllites of the Isaac Formation of the Cariboo Group.

History:

Mountjoy (1962) raised Walcott's (1913) Miette Formation to group status within the Windermere Supergroup. Charlesworth et al. (1967) proposed three formation names, only one of which has gained widespread acceptance, the Old Fort Point Formation. Campbell et al., (1973) recognized a three-fold subdivision of the Miette Group in the McBride map-area. The informal units, lower, middle and upper have subsequently gained widespread usage in the literature. McDonough and Simony (1986, 1988a) defined the middle Miette by its distinctive turbiditic grits and intervening green pelites.

References:

Campbell, R.B., Mountjoy, E.W., and Young, F.G., 1973. Geology of the McBride map-area, British Columbia (93 H) (Report, 5 figures and Map 1356A); Geological Survey of Canada, Paper 72-35, 104 p. + "A" Series Map 1356A, Geology, McBride, British Columbia, Scale: 1:250 000, NTS 93H.

Carey, J.A. and Simony, P.S., 1985. Stratigraphy, sedimentology and structure of Late Proterozoic Miette Group, Cushing Creek area, British Columbia; Canadian Society of Petroleum Geologists, Bulletin of Canadian Petroleum Geology , vol. 33, no. 2 (June), pp. 183-203.

Charlesworth, H.A.K., Weiner, J.L, Akehurst, A.J., Bielenstein, H.U., Evans, C.R., Griffiths, R.E., Remington, D.B., Stauffer, M.R., and Steiner J., 1967. Precambrian geology of the Jasper region, Alberta. Res. Counc. Alberta, Bulletin 23.

McDonough, M.R. and Simony, P.S., 1986. Geology of the northern Selwyn Range, western Main Ranges, Rocky Mountains, British Columbia, in, Current Research, Part A; Geological Survey of Canada, Paper 86-1A, pp. 619-626.

McDonough, M.R. and Simony, P.S., 1988a. Stratigraphy and structure of the Late Proterozoic Miette Group, northern Selwyn Range, Rocky Mountains, British Columbia, in, Current research, Part D; Geological Survey of Canada, Paper 88-1D, pp. 105-113.

Mountjoy, E.W., 1962. Mount Robson map-area (southeast), Rocky Mountains of Alberta and British Columbia; Geological Survey of Canada, Paper 61-31.

Walcott, C.D., 1913. Cambrian formations of the Robson Peak District, British Columbia and Alberta, Canada; Smithsonian Miscellaneous Collections, vol. 47, no. 12, pp. 327-343.