Revised Bedrock Topography and Stratigraphy Above Bedrock in the South Athabasca Oil Sands (SAOS) Region, Northeastern Alberta

This report summarizes studies related to updating the bedrock topography and the stratigraphy of the sediment units above bedrock in the South Athabasca Oil Sands region. Beneath the uplands in the study area, deep preglacial valleys are buried by hundreds of metres of a succession of multiple till, lacustrine, and fluvial deposits. The deposits at the base of the buried valleys are from the Ipiatik Formation of the Empress Group. These include the preglacial basal gravels of the House Member, which are capped by glaciolacustrine deposits of the Wappau Member followed by the glaciofluvial deposits of the Calder Member. On a higher level are the glaciofluvial deposits of the Winefred Formation. The Ipiatik and Winefred formations are buried by the reversely magnetized Bronson Lake Formation till. Above this is the fluvial Muriel Lake Formation, which is then overlain by Bonnyville Formation units 1 and 2, which are tills that in places have an intervening sand deposit. The Ethel Lake Formation, a glaciolacustrine and glaciofluvial package, rests on the Bonnyville Formation, likely where there were low spots in the preglacial topography. The Marie Creek, Sand River, and Grand Centre formations cap the succession, but these were not differentiated in this study due to limited data. The lowland areas are covered by relatively thin till deposits, with at least one subglacial channel, the Gregoire, incised deeply into the bedrock in the northeast of the study area, as well as the north and south Hangingstone channels north of the Stony Mountain Upland. This report includes a description of the cores and borehole data used to make picks on geophysical logs from oil and gas wells over the area.