gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1994.58A.1.81 A Comparison of Shale Compositions from the Western Canada Sedimentary Basin and the U.S. Gulf Coast: The Importance of Depositional Composition on Shale Diagenesis de Caritat P. Geological Survey of Norway, P.O. Box 3006-Lade, N-7002 Trondheim, Norway Bloch J. Scealu Modus, 2617 Cutler Ave. N.E., Albuquerque, New Mexico 87106, USA Hutcheon I. Department of Geology and Geophysics, The University of Calgary, Calgary, Alberta T2N 1N4, Canada Longstaffe F. J. Department of Earth Sciences, The University of Western Ontario, London, Ontario N6A 5B7, Canada Abercrombie H. J. Institute of Sedimentary and Petroleum Geology, Geological Survey of Canada, Calgary, Alberta T2L 2A7, Canada 8 1994 58A 1 150 151 Copyright © 1994, The Mineralogical Society 1994