What does the ichnological content of the Middle McMurray Formation tell us

Abstract Despite the abundant well-log and core data available for the McMurray Formation, the succession has remained difficult to interpret. Presently, a fundamental aspect of understanding the depositional nature of the McMurray Formation is whether or not the formation is dominantly estuarine or fluvial. Focussing on the informal middle McMurray, our detailed analysis of the McMurray Formation within the Kearl Oil Sands area critically evaluates the utility of collecting high-resolution ichnological and sedimentological data as a means to assess the depositional environments and to evaluate the evidence for an estuarine versus a tidally influenced fluvial depositional setting. This study asserts that the middle McMurray Formation within the Kearl Oil Sands area was deposited on estuarine point-bars. The examined dataset encompasses what are interpreted to be inner to middle estuarine depositional locales within a mesotidal regime. Integration of detailed ichnological and sedimentological data permits recognition of intertidal flat deposits which exist at sea level, and the identification of which provides a locally useful stratigraphic datum. Identification of successions of stacked tidally influenced channels of varying dimensions help identify stratigraphic levels of amalgamated estuarine channel bars and gives an approximation of relative changes in sea level.