Depositional Environments of the McMurray Formation in the Northernmost Activity of the Athabasca Oil Sands Area: Exploring the World’s Largest Energy System

Errin K. Kimball¹, Murray K. Gingras², S. George Pemberton², and Eric Swanbergson^3
1 Synenco Energy Inc, Calgary, AB
² University of Alberta, Edmonton, AB
³ Norwest Mines Corporation, Calgary, WY

The Northern Lights Project (NLP) is planned to be an integrated surface mineable oil sands operation. Located in the Athabasca Oil Sands Area, 110 kilometers north of Fort McMurray, townships 98 and 99, Ranges 5 to 7 west of the Fourth Meridian. The mineable oil-sand resources are hosted in the Lower Cretaceous (Aptian) McMurray Fm of the Mannville Gp. In the area, the McMurray Fm lay directly on eroded Devonian strata. McMurray units represent valley-fills and open-bay deposits that completely cover the older strata. Quaternary sedimentation removed some of the McMurray Fm in the NLP area. The resulting proximity of the oil sands to the surface makes them amenable to exploitation by mining methods. In general the McMurray Formation is informally subdivided into a lower fluvial unit, a middle estuarine unit and an upper marginal marine unit. In the NLP, the majority of the ore-grade bitumen is contained within the lower fluvial units, which accumulated in channel systems that drained the nearby Precambrian Athabasca quartzite. Thus, most of the bitumen at the Northern Lights Project is contained within relatively clean, medium- to coarse-grained quartz sand. Delineatation and modeling of channel trends has called for detailed collection of sedimentological and palynological data. These data reveal a lower, unburrowed, locally coaly, coarse grained stratum interpreted to have a fluvial affinity. Overlaying the fluvial are sporadically burrowed sands and muds that reflect accumulation in brackish-water channels. Above these are complex, locally burrowed sediments that may represent an open bay phase. Throughout the sedimentary column is evidence of subaerial exposure, suggesting that accommodation space was low and that the stratigraphy is exceedingly complex.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005