Controls on coal quality variation in the Cadomin-Luscar Coalfield, Alberta

Coal-Bearing Depositional Systems

“…8 section. A similar sulphur distribution has been reported by Langenberg et al (1989) from the Lower Cretaceous Jewel Seam in the Cadomin-Luscar-Grande Cache coalfields in west-central Alberta, Canada. Like the Borehole Seam, the Jewel Seam caps progradational shoreline deposits (MacDonald et al 1988) and is overlain by brackish-lagoonal sediments resulting in elevated sulphur values to occur at the bottom and top of the seam and dropping to less than 0.2% in its middle portion.…”

“…As has been noted by Bally et al (1966) the thickest and coarsest Kootenay sediments and their stratigraphic equivalents occur in the Front Ranges, whereas in the more distal Foothills they become finer and are overlain by coarse clastic rocks of the Lower Cretaceous Blaimore Group in the south and the Luscar Group with the coal-rich Grande Cache Member of the Gates Formation (see discussion of strand plain coals in Chap. 7.4) further north (McLean 1982;Leckie and Walker 1982;Leckie and Kalkreuth 1988;Macdonald et al 1988); Langenberg et al 1989;Kalkreuth and Leckie 1989;Kalkreuth et al 1989). Similarly, thick sandstone sequences of the coal-bearing Upper Cretaceous Belly River Formation and Edmonton Group overlie the thin distal end of the Lower Cretaceous deposits, thus indicating the outward migration of the foredeep with decreasing geological age.…”

“…In reference to the previously used example from New South Wales this means that the Wynn Seam does not have to be linked with the Bayswater Seam and vice versa. A well-documented example of a regressive Bayswater-type coal overlying several stacked coarsening-upward shoreline deposits without being preceded by transgressive coal formation is the above-mentioned Lower Cretaceous Jewel Seam, described by Langenberg et al (1989), Kalkreuth et al (1989), and Kalkreuth and Leckie (1989) from west-central Alberta, Canada. In Fig.…”

“…Because the methods of sediment supply and shoreline accretion are different in strand-plain settings, there is no such geometric contrast between peats formed under transgressive or regressive (shoreline progradation) conditions, and both trends may produce laterally very extensive coals. For example, Langenberg et al (1989), Kalkreuth et al (1989), and Kalkreuth and Leckie (1989) report on up to 12-m-thick Early Cretaceous strand-plain coals in Canada which rest on 15-to 35-mthick shoreface sands and gravels of the Gates Formation, that can be traced along strike for up to 230 km and down depositional dip for up to 90 km (Leckie and Walker 1982). Similar geometric relationships have been reported from eastern Australia, where several thick, low ash coking coals of the Moranbah and German Creek Coal Measures can be traced over a distance of 240 km along the western flank ofthe Bowen Basin in Queensland (Godfrey 1985).…”