Open File Report 2018-13

Author(s) Date 2018-12-11

This report is a compilation of both published and unpublished observations of hydrocarbons (bitumen) in glacial sediments and landforms in central Alberta. The recognition of bituminous and non-bituminous sandstone erratics in central Alberta spans more than a century of observations. Yet, their distribution, both spatially and stratigraphically, is poorly understood, and, when encountered within glacial sediments, bitumen erratics have been historically viewed as an anomalous and rare occurrence. Converging lines of petrological, palynological, and field-observational evidence suggest many bituminous, and non-bituminous, sandstone erratics in central Alberta were derived from glacial quarrying and plucking of the Grand Rapids Formation, specifically from the Wabasca oil sand deposit. These were transported into central Alberta relatively intact within southwest flowing ice-streams, and emplaced by glacial melt-out sedimentary processes. 

The knowledge that bituminous deposits can be naturally occurring within glacial sediments in central Alberta should preclude any a priori suppositions that such deposits are anthropogenic, resulting from inadvertent releases of industrial activity into natural systems. It is likely that future excavations or borings in glacial sediments of central Alberta will encounter more bituminous sand anomalies, as commented almost a hundred years ago by Rutherford (1928). At the very least, this report should move knowledge of the occurrence of bituminous erratics in central Alberta out of the realm of the unknown, to that of a known, and perhaps more predictable, geological phenomenon.

Andriashek, L.D. (2018): On the origin of oil sand and related bedrock erratics in glacial sediments of central Alberta; Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Open File Report 2018-13, 42 p.