Geological Characterization of the Lower Clearwater Shale in the Athabasca Oil Sands Area, Townships 87-99, Ranges 1-13, West of the Fourth Meridian

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.