Allostratigraphic subdivision of the Upper Cretaceous Dunvegan, Shaftesbury, and Kaskapau formations in the northwestern Alberta subsurface

The mid-Cenomanian Dunvegan Formation is a lithostratigraphically defined clastic wedge comprising sandstones, siltstones, and mudstones. Over the 30 000 km² study area, the Dunvegan Formation has been subdivided into seven allomembers (from youngest to oldest, A to G). A radioactive shale horizon (FSU marker) occurs throughout the study area. It lies between 10 and 40 m above the Fish Scale Marker Horizon within the underlying upper …