Saskatchewan Report 223 Industry and Resources Saskatchewan Geological Survey Jura-Cretaceous Success Formation and Lower Cretaceous Mannville Group of Saskatchewan J.E. Christopher 2003 19 48 Printed under the authority of the Minister of Industry and Resources Although the Department of Industry and Resources has exercised all reasonable care in the compilation, interpretation, and production of this report, it is not possible to ensure total accuracy, and all persons who rely on the information contained herein do so at their own risk. The Department of Industry and Resources and the Government of Saskatchewan do not accept liability for any errors, omissions or inaccuracies that may be included in, or derived from, this report. Cover: Clearwater River Valley at Contact Rapids (1.5 km south of latitude 56º45'; latitude 109º30'), Saskatchewan. View towards the north. Scarp of Middle Devonian Methy dolomite at right. Dolomite underlies the Lower Cretaceous McMurray Formation outcrops recessed in the valley walls. Photo by J.E. Christopher. Additional copies of this digital report may be obtained by contacting: Saskatchewan Industry and Resources Publications 2101 Scarth Street, 3rd floor Regina, SK S4P 3V7 (306) 787-2528 FAX: (306) 787-2527 E-mail: [email protected] Recommended Citation: Christopher, J.E. (2003): Jura-Cretaceous Success Formation and Lower Cretaceous Mannville Group of Saskatchewan; Sask. Industry and Resources, Report 223, CD-ROM. Editors: C.F. Gilboy C.T. Harper D.F. Paterson RnD Technical Production: E.H. Nickel M.E. Opseth Production Editor: C.L. Brown Saskatchewan Industry and Resources ii Report 223 Foreword This report, the first on CD to be released by the Petroleum Geology Branch, describes the geology of the Success Formation and the Mannville Group wherever these units are present in Saskatchewan. It combines the results of more than thirty years of detailed and meticulous research with insightful interpretations based on lengthy experience with, and deep understanding, of Saskatchewan’s Mesozoic stratigraphy and sedimentology. Its author, Dr. Jim Christopher, started his career with this department (then named Mineral Resources) in 1959, when he worked on the Upper Devonian Three Forks Group. Jim first focused his attention on problems of the Success and the Mannville in the late 1960s, his work culminating in the 1974 publication of “The Upper Jurassic Vanguard and Lower Cretaceous Mannville Groups of Southwestern Saskatchewan”. In 1975, Jim was promoted to Directorship of the Saskatchewan Geological Survey. Upon his retirement in 1987, he returned to full-time studies of the Success and Mannville, largely in an emeritus capacity. Completion of this long-awaited report has been complicated by the changeover from printing reports in conventional paper format to reproducing them as CDs in electronic form. As such, it is a pilot project, and we look forward to feedback from users telling us what works well and what problems require our attention. It is my particular expectation that this report, with its numerous maps, cross-sections, core descriptions, and related databases, will prove to be of great value to companies which are exploring for or developing oil and/or natural gas accumulations in the Success and the Mannville, or plan to do so. It also sets a high standard for other geoscientists working on Saskatchewan’s Phanerozoic strata to follow. In closing, I congratulate Dr. Christopher and the report’s production team for making this superb work so readily available to anyone who wishes to use it. C.F. Gilboy Director, Petroleum and Geology Branch Exploration and Geological Services Regina April 2003 Saskatchewan Industry and Resources iii Report 223 Abstract The unconformity-bounded Success Formation and its homologues are found in five non-contiguous regions in southern and central Saskatchewan, and are remnants of widespread kaolinitic and sideritic quartzose sandstone deposits, up to 120 m thick, that blanketed much of the Prairie Provinces in the Late Jurassic and Neocomian. They are survivors of the succeeding Aptian pre-Mannville erosion, to which the relief of the sub-Cretaceous erosion surface is generally attributed. These sandstone deposits include a significant chert component close to the Mississippian limestone exposures, and coal beds in the subsiding localities of southeastern Saskatchewan. The dominantly fluviatile genesis of the Success sandstone yields to marine facies on the approaches to the Williston Basin. The Mannville Group (restricted) comprises the Cantuar and Pense formations. The Cantuar Formation infills and covers a topography of valleys and terraces, the morphology of which is controlled by major structural blocks. These valleys were deepest across the Swift Current Platform of southwestern Saskatchewan, from where they radiated into major drainage systems west into Alberta, and east and northwest across central Saskatchewan into the McMurray basin of east-central Alberta. The formation forms a regional wedge, up to 240 m thick in the northwest, and comprises seven members (Dina, Cummings, Lloydminster, Rex, General Petroleums, Sparky, and Waseca). Quartzose sandstone, siltstone and mudstone, and subbituminous coal form broad lenticular and narrow linear bodies separated by hiatuses and erosional discontinuities. Hemicyclic sequences of grey-black shale, bioturbated shale and sandstone, and flasered and cross-bedded sandstone are widespread. The Cantuar basin underwent oscillatory marine transgressions, from the Clearwater–Grand Rapids basin of central Alberta into the Williston Basin, that were offset by progradations from the southwestern Rocky Mountain region. A significant regression culminated in deposition of the Sparky coal beds. The generally marine Pense Formation overlies the Cantuar Formation on a planar disconformity, under which the latter is truncated to its base across the Punnichy Arch in east-central Saskatchewan. It represents a change of depocentre to one controlled by the Big Horn Basin of Wyoming and its extension north to a subsiding Swift Current Platform. In southwestern Saskatchewan, the formation comprises as many as four lithological units of black shale, bioturbated and flasered black shale, and quartzose sandstone, with capping, well-sorted, flat-bedded and cross-bedded quartzose sandstone. The upper units grade southeastward into shale, and are incorporated into the Joli Fou Formation of the Williston Basin. In central Saskatchewan, the marine-deltaic McLaren and Colony members are regarded as equivalents. Westward from the Swift Current Platform, the Pense is partially truncated under the shale of the Joli Fou Formation of the Colorado Group. The Success-Mannville structural setting is delineated by the major Precambrian basement blocks, which changed the configuration of the depositional basin by vertical motion in opposition to and in conjunction with one another. Lineaments, comprising a north- and east-trending set and a northwest- and northeast-trending set, exercised subsidiary control. There are some 65 Mannville oil pools distributed across the Lloydminster and Kindersley districts. The major ones occupy the floor of a northeasterly rising amphitheatre, but vary in elevation and are warped onto highs and into lows. These discordances are attributed to irregular downsets of the structural datum by sporadic removal of salt from the Middle Devonian Elk Point evaporite beds, and to congealing of the oil in place by biodegradation. In southwestern Saskatchewan, the less permeable Mannville rocks act as a reservoir seal to Success and Upper Jurassic Roseray pools at the updip ends of strata terminated at the sub-Cantuar unconformity. In southeastern Saskatchewan, Mannville oil is pooled in channel sandstone updip against the unconformity with the Jurassic. The northern natural-gas fields of west-central Saskatchewan extend north from Twp. 52 to 68 in a narrow belt between the Saskatchewan-Alberta boundary and Rge. 21, W 3rd Mer., and are mostly in upper Mannville (Waseca, McLaren, and Colony) progradational sandstone built out from the west into offshore, more argillaceous facies. They are enclosed on small structural terraces and anticlines and across narrow troughs, above the eastern, partially dissolved mass of the Lower Elk Point evaporite beds that overlie the topographic relief of the Precambrian basement. The more than 25 pools constitute the second largest gas-producing district of the province. Saskatchewan Industry and Resources iv Report 223 Contents Foreword ......................................................................................................................................................................iii Abstract ........................................................................................................................................................................iv Contents......................................................................................................................................................................... v Figures ................................................................................................................................................................vii Tables...................................................................................................................................................................ix Introduction ...................................................................................................................................................................1