This report focuses on regional geological mapping of the Cretaceous strata, specifically the extent and thickness of the lower Clearwater shale unit, that overlay the Wabiskaw-McMurray bitumen deposit.
The study area (Twp. 87 to 99, Rge. 1 to 13, W 4th Mer.) is located in the Athabasca Oil Sands Area in northeastern Alberta and encompasses most of the surface-mineable area and the northeastern extents of the Wabiskaw-McMurray bitumen deposit.
The objective of the study was to characterize the units above and below the bitumen-bearing zones. We mapped the erosional zero edge of the unit in the northern part of the study area highlighting where the lower Clearwater shale unit is thin (<5 m thick) or absent. Over most of its extent in the study area, the lower Clearwater shale was found to be between 20 and 30 m thick. Results from petrographic and mineralogical analyses on shale, silty shale, and siltstone samples showed that the lower Clearwater shale ranged from a quartz- rich shale to a carbonaceous silty shale to argillaceous siltstone. The total clay content of the samples ranged from 13% to 31%. In addition, Light Detection and Ranging (LiDAR) bare earth digital elevation model (DEM) images were used to locate the surface expression of sinkholes.