Sedimentology of the Mist Mountain formation, in the Fording River area, southeastern Canadian Rocky Mountains

The Upper Jurassic-Lower Cretaceous Mist Mountain Formation at the Fording Mine in southeastern British Columbia is a 550 metre thick interval of non-marine, coal-bearing sediments. Three units can be distinguished in the stratigraphic sequence based on sandstone body geometry and coal seam characteristics. Unit I, the lowermost unit, represents prograding lower coastal plain deposits. Two major distributary channels trended northwest-southeast through the study area. These channels limited the lateral extent of coexisting peat swamps responsible for coal seams 1, 2 and 3. The dominantly herbaceous peats grew in hummock and depression topography in interchannel areas. Crevasse splay and overbank deposits flooded peat swamps causing cessation of growth and deposition of fine-grained muds and silts on peat surfaces. These mud and silt beds are the mudstone and siltstone partings that occur in the Mist Mountain coals. Unit II sediments accumulated in a fluvial-flood plain environment. Rivers trended northeast-southwest in a wide meander belt. Peat swamps supported herbaceous and arboraceous plants and were frequently disturbed by coexisting rivers. River and splay waters actively eroded peats and deposited fine- to medium-grained sediments on peat surfaces. The sediments of Unit III were deposited in a flood plain dominated environment on the upper coastal plain. Major rivers were concentrated outside of the study area allowing thick forest peat accumulations. Lake and flood waters covered peats causing mudstone splits in some coal seams and some argillaceous coals. Coals of the Mist Mountain Formation are low in sulfur (