The McMurray Sediment Routing System

The Cretaceous McMurray Formation consists of amalgamated 25–40 m thick point-bar sands that serve as reservoirs for the Alberta Oil Sands in the Mesozoic foreland of Alberta, Canada. This presentation reconstructs the McMurray sediment-routing system based on ~20,000 detrital zircon (DZ) U–Pb ages from deposits in Alberta and time-equivalent deposits in the Rocky Mountains and midcontinent US.

McMurray deposits in Alberta display three distinct provenance signatures. The axial south-to-north McMurray in east-central Alberta is dominated by Paleozoic and Meso–Proterozoic DZ U–Pb age groups derived from the Appalachian Cordillera of the eastern US, with a minor contribution from the Mesozoic Western Cordillera magmatic arc. The second signature occurs in the Ft. McMurray area 300 km farther north, and is dominated by Paleo–Proterozoic and Archean age groups from the Canadian shield. Farther north, the McMurray consists of a 50–50 mix of south-derived age groups from the US, and east-derived age groups from Canada.

South-derived axial McMurray U–Pb age distributions are also indistinct from age distributions in Cretaceous fluvial sandstones of the US midcontinent, which represent McMurray headwaters, and define a fluvial system with sediments derived from the Appalachian Cordillera in the SE US (~40% of the total), and from the Mesozoic Western Cordillera in the SW US (~60%). McMurray fluvial deposits therefore represent a continental-scale system, the Mississippi or Amazon of its time, with a ~6*106 km2 catchment area, headwaters that extended from the SW to SE US, and north to the Canadian shield, and channels with bankfull depths of 25–40 m.