Earth Sciences Report 2007-05

Earth Sciences Report 2007-05

ESR 2007-05

Regional Correlations of the Ardley Coal Zone, Alberta

The Ardley Coal Zone forms part of the Scollard Formation of the Alberta Plains and contains one of Alberta's main coal resources. Information on the Ardley Coal Zone is often reported using Foothills coal seam terminology such as Val d'Or and Mynheer seams, implying correlation with the Coalspur Coal Zone of the Foothills area. However, cross sections show that individual seams come and go, although some could be correlated with confidence over distances of over 50 km. Very detailed correlations of coal seams based on magneto-stratigraphy, palynology and petrography is available for the coal seams near the eastern outcrop edge of the Ardley Bend/Scollard Canyon area. In this area the traditional terminology of Lower Ardley (#13) and Ardley (#14) coal seams has been useful.

The use of a unified numeric terminology is possible for the Ardley Coal Zone in the subsurface, enabling regional correlation. In the western part of the basin, this terminology can be tied to the Foothills coal seam terminology of the Coal Valley area. The best coal seam for correlation purposes is the Lower Ardley (Seam 650; also designated as #13, Nevis and Mynheer Coal seams), the base of which marks the Cretaceous/Tertiary boundary. However, many other coal seams (such as seam 100 and 150) are also correlatable over large areas. A diagnostic palynoflora, embraced by the lower part of the Aquilapollenites spinulosus Zone, has been found to be characteristic of the Val d'Or Coal Seam (seam 75). The conditions suitable for peat deposition, which formed the Ardley Coal Zone, lasted at least 1 Ma, as indicated by U/Pb dating of zircons in bentonites. Regional cross sections constructed for this study provide a detailed picture of the wedge of sediment of this stratigraphic zone between the Cretaceous/Tertiary boundary and the unconformity at the base of the Paskapoo Formation.

Langenberg, C.W., Berhane, H., Sweet, A.R., Marchioni, D. and Heaman, L.M. (2007): Regional correlations of the Ardley Coal Zone, Alberta; Alberta Energy and Utilities Board, EUB/AGS Earth Sciences Report 2007-05, 32 p.