Open File Report 1990-04

The study area of mapsheet NTS 83E/15 (Pierre Greys Lakes) is located in west-central Alberta. The communities of Hinton (83F/5) and Grande Cache (83E/14) are the primary population centers near the study area. Almost all of mapsheet 83E/15 is located within the Berland IRP: Willmore Wilderness Provincial Park, located in the extreme southwest corner of the mapsheet, is not part of the Berland IRP.

Within the mapsheet 83E/15, coal measures are deposited amid thick successions of sandstones, siltstones, shales and conglomerates. These coal-bearing sequences are part of the Lower Cretaceous Luscar Group, upper Cretaceous Brazeau Formation and Paleocene Coalspur Formations.

The Luscar Group consists of sandstones, shales, conglomerates and coals, deposited predominantly in nonmarine environments. Strata of the Lower Cretaceous Luscar Group have been subjected to deformation which has produced northwesterly trending thrust faults and folds. As a result, the Luscar Group coal seams are now exposed in a series of northwest trending thrust sheets and associated folds. Often the coal seams have been further locally folded and faulted. Depending on the severity of these local structural complexities, and acknowledging a general discontinuity of coal outcrops in the Inner Foothills, coal seam correlations and evaluations can be extremely difficult. Within the mapsheet, up to eight seams are present within the Luscar Group. The seams have an average aggregate thickness of 21 meters and are contained within a 150+ meter-thick sedimentary sequence. Average seam thicknesses range from 1.5 to 3.5 meters. Seam correlations are preliminary.

The Entrance Conglomerate which normally separates the Brazeau and Coalspur Formations has not been identified within the mapsheet area. For obvious reasons, it follows that the Brazeau and Coalspur Formations have not be positively differentiated on this mapsheet. Combined, the two formations consist of primarily nonmarine sandstones, conglomerates, shales and (minor...?) coals; the formations lie conformably above the marine Wapiabi Formation.

Within the mapsheet area, three coal occurrences are believed to be from the Coalspur Formation (which contains the Coal Valley Coal Zone/Kakwa Coal Measures). The known coal occurrences include two outcrops, each 0.3 meters thick, and one 1.5 meter thick drillhole intersection. No correlations could be established for the Coalspur Formation coals. No coal occurrences have been noted in the Brazeau Formation however, no coal exploration drilling has been done in the area of Brazeau sediments.

The undivided Upper Cretaceous Brazeau Formation are located in a series of gentle anticlines and synclines that trend in a northwesterly strike direction. In the northeastern part of the map area the Paleocene Coalspur and Paskapoo strata dip between 10 and 30 degrees towards the northeast.

In general, from a coal resource/exploration point of view, the map area has been superficially examined, Only two areas, the ERCB's A La Peche Lake Coal Field and the Sterne Creek area have a good exploration database but structural geology studies are needed for both areas. The Sterne Creek area includes the ERCB Susa creek coal deposit; described as a 'Small Isolated Deposit'. Within the Sterne creek area, seams # 3, 4 and 10 from the Grande Cache area can be identified and traced. Seam 3 can also be identified in the La Peche Lake area and from the Sterne Creek area southeast to the Muskeg River.

Little data is available and the coal development potential is uncertain for most of the remaining map area particularly in the northeast where the Brazeau Formation (containing the Cutbank Coal Measures) and the Coalspur Formation (which contains the Coal Valley Coal Zone/Kakwa Coal Measures) have been projected. A promising area for future work is the Coal Valley Coal Zone trend in the east apart (Pierre Greys Lakes, Lone Teepee and Burleigh creeks area) of the map area where a preglacial valley may mean lower overburden than along trend to the northwest. Additional subsurface geological studies, including the construction of regional cross-sections and seam correlations, are needed in the eastern and Sterne Creek/A La Peche Lake regions of the map area.

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Richardson, R.J.H., Langenberg, C.W., Chao, D.K. and Fietz, D.W. (1990): Alberta Geological Survey - Coal geology: Coal compilation project - Pierre Greys Lakes; NTS 83E/15; Alberta Research Council, ARC/AGS Open File Report 1990-04, 55 p.