Sandstone Channels and Associated Coal-Bearing Strata in Scollard Formation, West-Central Alberta

Cristina Pana, Andrew Beaton, Desmond Wynne, and Mike Berhane
Alberta Geological Survey, Edmonton, AB

The Scollard Fm is included within the uppermost Cretaceous –Tertiary nonmarine clastic wedge of the Alberta foreland. Late Cretaceous-Paleocene tectonic and climatic factors significantly influenced depositional processes and induced important coal accumulation mainly in the upper part of the Scollard Fm.

The Scollard Fm may be subdivided into three sub-basins, each with a slightly different evolution. All three sub-basins have the same components of alluvial drainage systems but the medial and distal parts of the drainage system in every sub-basin were dependent upon the particular sediment supply, local orientation and steepness of paleoslope, and the deposition space available.

The upper part of Scollard Fm, including the Ardley coal zone, represents multi-cyclic fluvial deposition; four regionally mappable cycles are capped by coal accumulation. Coals associated with mid- to distal – fan deposits (peat swamps and lowland moors) are related to limited clastic supply due to tectonic quiescence and a humid climate.

A depositional model was developed to decipher the Scollard Fm architecture, defined by the geometry of the major sandstone channels and the lateral continuity of the lithologic markers. The model shows the Ardley coal zone sub-units, their lateral continuity and channel - coal relationships. Regional and local cross-sections and maps support the details of the model.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005