FAULT‐BLOCK TECTONISM IN THE DEVONIAN SUBSURFACE, WESTERN CANADA BASIN

• Published in: Journal of Petroleum Geology
• Main Authors: Greggs, R. G., Greggs, D. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Earth and Planetary Sciences (miscellaneous); Geology; Energy Engineering and Power Technology; Fuel Technology; Canada; canada basin
• Online Access: http://dx.doi.org/10.1111/j.1747-5457.1989.tb00239.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1747-5457.1989.tb00239.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1747-5457.1989.tb00239.x

An alternative model for the formation of Devonian carbonate reefs in the Western Canada Basin is proposed. This model is based on the epeiric clear‐water sedimentation model of Irwin (1965), with structural modfication throughout the Phanerozoic by repeated PreCambrian basement tectonism. The cratonic structural pattern is dominantly controlled by the global regmatic fracture‐system, which comprises a series of NW ‐ SE and NE ‐ SW vertical faults. These faults delineate a mosaic of fault blocks across the entire Western Canada Basin. Wrench faulting and vertical epeirogenic movements throughout the Paleozoic. Mesozoic, and Cenozoic subjected these blocks to further tectonic effects ‐ structural deformation and hydrothermal diagenesis. Preservation of down‐faulted carbonate blocks, and their subsequent isostatic recovery into overlying anhydrite or shale sequences, has led to the formation of carbonate complexes generally referred to as “organic reefs”. In addition, repeated emergence and submergence of the cratonic platform, particularly throughout the Middle and Upper Paleozoic, produced numerous regional and inter‐regional unconformities. These periods of erosion contributed to the leaching, and partial dolomitization, of the Devonian carbonates formed during periods of cratonic submergence. Repeated faulting is considered to have been a major factor in the diagenetic alteration of Devonian carbonates through associated hydrothermal activity, and a dominant control in the migration of hydrocarbons.