An Upper Cretaceous Fluvio-Lacustrine Coal-Bearing Sequence, Red Deer Area, Alberta, Canada
- R. A. Rahmani and
- R. M. Flores
Published Online: 28 APR 2009
Copyright © 1984 The International Association of Sedimentologists
Sedimentology of Coal and Coal-Bearing Sequences
How to Cite
Nurkowski, J. R. and Rahmani, R. A. (1985) An Upper Cretaceous Fluvio-Lacustrine Coal-Bearing Sequence, Red Deer Area, Alberta, Canada, in Sedimentology of Coal and Coal-Bearing Sequences (eds R. A. Rahmani and R. M. Flores), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303797.ch9
- Published Online: 28 APR 2009
- Published Print: 26 MAR 1985
Print ISBN: 9780632012862
Online ISBN: 9781444303797
- Upper cretaceous fluvio-lacustrine coal-bearing sequence – Red Deer Area, Alberta, Canada;
- fine-grained unit;
- coal-bearing unit;
- oyster fragments
The upper Horseshoe Canyon Formation in central Alberta is subdivided into two informal lithostratigraphic units: a lower fine-grained unit and an upper coal-bearing unit, containing the traditionally named Carbon and Thompson coal zones. The fine-grained unit consists mainly of siltstones with minor shales and fine-grained sandstones and is characterized by coarsening-upward sequences. Coals and carbonaceous materials are absent. The coal-bearing unit consists of clastics ranging in grain size up to coarse-grained sandstone, as well as coals and other carbonaceous sediments. Sandstones have an fining-upward character and, in outcrop, display lateral accretion bedding. Subsurface investigation of the coal-bearing unit indicates thick sandstone and coal accumulations form a NW–SE trending belt, a direction similar to the inferred palaeodrainage direction determined from a previous heavy mineral dispersal study.
Evidence suggests a lacustrine origin for the older fine-grained unit. Sediments and coals of the coal-bearing unit accumulated in a meandering river environment, with the coarse clastics representing active channel-fill and the finer clastics representing inactive channel-fill and overbank deposits. The coals accumulated in back-levée, channel-fill, and flood basin swamps, preferentially developing in areas parallel to the palaeodrainage direction. Together with the fine-grained unit, this sequence represents a south-eastward prograding system.
Exploration for thick seams within the Carbon and Thompson coal zones should be concentrated within the NS-SE trending belt of thick coal accumulation. Because the regional dip is to the west, exploitation of coal seams in the western portion of the study area would be limited to underground mining and/or in situ gasification.