ABSTRACT

At various times during the Late Jurassic to Paleocene, tectonic, sedimentological and ecological factors combined to provide favourable coalforming environments in the Western Canada Sedimentary Basin. More than 85 per cent of Canada's known coal resources of "immediate interest" occur in this basin. The coal deposits are widespread and have diverse characteristics with regard to their composition, properties, degree of maturation (rank) and geological complexity. This reflects regional variations in environments of deposition and post-depositional, structural development of the basin. In addition to the coal resources of immediate interest, vast quantities of coal occur in seams that are too thin and/or too deep for present exploitation; these are referred to as coal resources of "future interest" and include significant quantities in the Mannville Group beneath the Interior Plains.

The Front Ranges and Foothills of the Rocky Mountains have major deposits of metallurgical and thermal coals (semianthracite to high volatile bituminous) in the Jurassic-Cretaceous Mist Mountain Formation and in the Lower Cretaceous Gething (Aptian) and Gates (Albian) formations. In the Outer Foothills, large deposits of Upper Cretaceous and Paleocene thermal coals (high volatile bituminous) occur in the Belly River (Campanian) and Coalspur (Maastrichtian-Paleocene) formations. In the Interior Plains, important resources of Upper Cretaceous to Paleocene sub-bituminous and lignitic coals occur in the Belly River, Edmonton and Wapiti groups and in the Paleocene Paskapoo and Ravenscrag formations.

The structural framework within which these coals occur ranges from complexly folded and faulted strata in the mountains to relatively uncomplicated flat-lying strata in the Interior Plains. Coal rank may be influenced to some extent by stacking of thrust sheets in the mountains, but seems mainly to be a function of depth of stratigraphic burial, increasing from east to west.

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