Seismic interpretation and structural analysis of the Beaufort - Mackenzie Basin

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Regional 2D seismic lines have been interpreted throughout the basin for a better understanding of regional stratigraphy, structural styles, as well as petroleum. The rift sequences and Upper Cretaceous are interpreted only in the east basin margin. For the Lower Tertiary strata, including Aklak, Taglu and Richards sequences, we have better control from exploration wells and a better understanding in east basin margin and Outer Mackenzie Delta area. In the rest of the basin, the interpretation of the Lower Tertiary is less reliable because of poor data quality and significant burial depths. The Oligocene and Upper Tertiary strata, including Kugmallit, Mackenzie Bay, Akpak and Iperk sequences are interpreted throughout the basin, except where they have been completely removed by erosion. Five regional seismic sections illustrate the general features of the sequence boundaries and the structural deformation of the entire basin. The structural styles and evolution of Late Mesozoic-Cenozoic Beaufort-Mackenzie Basin vary considerably from west to east and from the basin margin to offshore due to its unique tectonic environment. The basin started as a rift during Late Jurassic and Early Cretaceous. After rift, the development of the west basin was dominated by contractional tectonics but east basin was continuously in an extensional regime. Structural analysis is focused on the variation of structural styles and the major structural boundaries that separate different tectonic environments. The major conclusions reached by this research include: - In west basin, the most important deformation is the extensively developed Early Tertiary thrust faults and folds (pre-Richards Sequence). Deformation may have begun as broad and gentle folds during the late Paleocene or early Eocene, but the current geometry of the contractional deformation is a result of mid-Eocene (pre-Richards Sequence) tectonism. Contractional deformation is mainly limited to west of the Blow River High. Richards and overlying strata are relatively undeformed. - In east basin, the early stage of contraction may have occurred at the end of the rift stage (end of Early Cretaceous) but is limited to a narrow zone in southwestern Kugmallit Trough. Deformation in most of the east basin is dominated by post-Late Eocene syn-depositional extension when deposition of the Richards Sequence began. The extensional regime was terminated by Late Miocene inversion. - The structural boundary separating the west from the east basin is a broad transition zone consisting of the Blow River and Tununuk highs and their south extensions. - Late Miocene inversion in the east basin was mainly limited to south of Tarsuit-Amauligak Fault zone and in southwestern Kugmallit Trough. Late Miocene tectonics also caused strike-slip along Taglu Fault Zone. - North of Tarsuit-Amauligak Fault Zone extensional structures dominate.