Lithostratigraphy, sequence stratigraphy and paleoenvironments of the Upper Colorado Group in southern Alberta and southwestern Saskatchewan: Definition of the Carlile and Niobrara Formations (Upper Turonian to Upper Santonian)

The Upper Turonian to Santonian Upper Colorado Group in southern Alberta and southwestern Saskatchewan, Canada consists of a 120 to 350 m thick shaly interval, which prior to this study lacked a formal stratigraphic definition and subdivision. Using a multidisciplinary approach this thesis resolves the gap in the stratigraphic record and describes in detail the lithostratigraphy, sequence stratigraphy and paleoenvironments of the Upper Colorado Group. The interval, which is defined by the older Carlile Formation overlain by the Niobrara Formation, contains thirteen fourth order sequences with eight facies and four facies associations. These sequences can be correlated across the basin and demonstrate a complex sea-level fluctuations and basin infill history.; The Carlile Formation of Late Turonian age (30 to 160 m thick) is defined as the lower part of the Upper Colorado Group conformably overlying the Second White Specks Formation. The Carlile Formation represents the regressive part of the second order Greenhorn Cycle and is characterized by non-calcareous shale with minor sandstone beds and siderite concretions. The Formation is informally subdivided into a lower, middle and upper members, which correlate with the Haven and Opabin members of the Blackstone Formation and the Cardium Formation, respectively.; Sequences F1 to F7 are correlated within the distal marine Carlile Formation. Low-angle clinoforms strata dominate the internal stratal pattern and sequence boundaries are parallel to sub-parallel to one another. In the lower sequences, strata dip from west to east whereas the upper sequences are dominated by strata that dip from east and west towards the central part of the study area. This indicates a shift in sediment source from dominantly the west to both from west and east. The upper two sequences are truncated by a major unconformity and indicate the maximum regression of the Greenhorn Cycle creating a narrow seaway located in eastern Alberta and western Saskatchewan.; The Niobrara Formation (80 to 240 m thick) unconformable overlies the Carlile Formation and is characterized as a partly calcareous to calcareous shale with intervals of abundant bentonites and widespread fine-grained sandstones. The Formation represents the transgressive part of the second order Niobrara cycle and is subdivided into the bentonite-rich Verger Member, the sand-rich Medicine Hat Member and the calcareous First White Specks Member. (Abstract shortened by UMI.)...