Seismic geomorphology and sedimentology of a tidally influenced river deposit, Lower Cretaceous Athabasca oil sands, Alberta, Canada Stephen M. Hubbard, Derald G. Smith, Haley Nielsen, Dale A. Leckie, Milovan Fustic, Ronald J. Spencer, and Lorraine Bloom ABSTRACT The bitumen of the Lower Cretaceous McMurray Formation in Alberta arguably represents one of the most important hydrocarbon accumulations in the world. In-situ development relies on heat transfer through the reservoir via horizontal steam injection wells placed 4 to 6 m (13–20 ft) above horizontal producers near the base of the sandstone reservoirs. Given this technology, understanding the distribution of the resource is paramount for a successful development program. Sedimen- tary facies provide a direct control on bitumen distribution and recovery. Most facies models developed to describe and predict sedi- mentary units of the McMurray Formation consider fluvial, estuarine, and/or deltaic depositional settings. In-situ develop- ment, however, requires a particularly high-resolution sedimen- tologic interpretation. High-quality three-dimensional seismic reflection data and extensive drill cores from acreage located approximately 50 km (31 mi) south of Fort McMurray provide important insights into the sedimentologic organization of res- ervoir and nonreservoir deposits in the upper one third (40 m [131 ft]) of the reservoir interval. Geomorphologic charac- teristics of the strata observed in seismic time slices reveal that a fluvial depositional setting was prevalent. Ichnologic and palynologic data, as well as sedimentary structures suggestive of tidal processes, indicate a marine influence in the upper AUTHORS Stephen M. Hubbard  Department of Geo- science, University of Calgary, Calgary, Alberta, Canada; shubbard@ucalgary.ca Steve Hubbard is an assistant professor in the De- partment of Geoscience at the University of Calgary. He received his B.Sc. and M.Sc. degrees in geology from the University of Alberta, and his Ph.D. in geological and environmental sciences from Stan- ford University. His research interests include the evolution and stratigraphic architecture of channel deposits from nonmarine to deep-marine settings. Derald G. Smith  Department of Geography, University of Calgary, Calgary, Alberta, Canada; dgsmit@ucalgary.ca Derald Smith, now professor emeritus, retired from the University of Calgary in 2006. His academic interests are in fluvial geomorphology, sedimentol- ogy, and stratigraphy. He received his Ph.D. from Johns Hopkins University, supervised by the late “Reds” M. Gordon Wolman. His initial academic inspiration came from Chester Beaty, Don Winston, James Peterson, and David Alt from the University of Montana. His recent retirement passion is alpine ski racing at the master’s level. Haley Nielsen  Department of Geoscience, University of Calgary, Calgary, Alberta, Canada; haley.nielsen@encana.com Haley Nielsen graduated with her B.Sc. degree from the Department of Geoscience at the University of Calgary in 2008. Her undergraduate honors thesis focused on sedimentary characterization of channels in the McMurray Formation. Since graduation, she has been working as a geologist at Encana in Calgary. Dale A. Leckie  Nexen, Inc., Calgary, Alberta, Canada; dale_leckie@nexeninc.com Dale Leckie, chief geologist at Nexen, Inc., specializes in petroleum systems, focusing on sedimentology, marine and nonmarine sequence stratigraphy, basin analysis, and unconventional hydrocarbon reser- voirs. He was president of SEPM, is associate editor for the AAPG Bulletin, co-organized a 2007 AAPG Hedberg Conference on Heavy Oil and Bitumen in Foreland Basins, and has coedited books from AAPG, SEPM, and the Canadian Society of Petro- leum Geologists (CSPG). Milovan Fustic  Nexen, Inc., Calgary, Alberta, Canada; milovan_fustic@nexeninc.com Milovan Fustic is a geologist at Nexen, Inc., in Calgary. He received a B.Sc. honors degree in geology from the University of Belgrade (Serbia) and a Ph.D. in Copyright ©2011. The American Association of Petroleum Geologists. All rights reserved. Manuscript received June 28, 2010; provisional acceptance September 14, 2010; revised manuscript received November 8, 2010; final acceptance December 13, 2010. DOI:10.1306/12131010111 AAPG Bulletin, v. 95, no. 7 (July 2011), pp. 1123 – 1145 1123