Report 90

Report 90

REP 90

Modelling of the Sub-Cretaceous Unconformity: Elevation, Subcrop Mapping, and Paleotopography in the Peace River and Slave Lake Regions, Alberta (NTS 83N, 83O, 84C and 84B)

Author(s) Peterson, J.T. MacCormack, K.E. Date 2016-03-28

The sub-Cretaceous unconformity is an important regional surface across the Alberta Basin that represents a significant period of non-deposition and erosion initiated after the deposition of upper Jurassic/lowermost Cretaceous sediments of the first foreland basin clastic wedge. The variable topography of the sub-Cretaceous unconformity is an important control on sedimentation and preservation of major petroleum bearing Cretaceous formations in areas such as the Athabasca, Peace River, and Cold Lake oil sands areas. Previous modelling of the sub-Cretaceous unconformity surface was completed using datasets from multiple sources, resulting in a variable quality surface due to inconsistent picking criteria between sources, colocated data, and clustered data distribution. To ensure consistency and increase our confidence in this important surface model, the sub-Cretaceous unconformity was mapped across the study area by reviewing the well logs for 4,175 wells and identifying the elevation of the unconformity surface and the subcropping formation. Additional modelling was then performed to generate a paleotopographic surface, representing the position of the unconformity surface prior to the onset of Cretaceous sedimentation.

Peterson, J.T. and MacCormack, K.E. (2016): Modelling of the sub-Cretaceous unconformity: elevation, subcrop mapping, and paleotopography in the Peace River and Slave Lake regions, Alberta (NTS 83N, 83O, 84C, 84B); Alberta Energy Regulator, AER/AGS Report 90, 30 p.