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The AAPG/Datapages Combined Publications Database

CSPG Bulletin


Bulletin of Canadian Petroleum Geology
Vol. 39 (1991), No. 3. (September), Pages 270-282

A Re-examination of the Paskapoo Formation in the Central Alberta Plains: The Designation of Three New Members

Thomas D. Demchuk, L.V. Hills


Paskapoo Formation strata in the central Alberta Plains can be divided into three members based on the subsurface and outcrop investigation of these strata in the Red Deer-Lacombe and Obed-Marsh areas. Two subsurface sections (Alberta Research Council Coal Exploration Coreholes 2-82 and 3-82) in the Red Deer-Lacombe area provide uninterrupted sequences of Paskapoo Formation strata in this area. These sections are hereby designated principal reference sections for this formation, and contain the type-sections for the newly proposed Haynes and Lacombe members. These principal reference sections allow for the placement of isolated outcrops of Paskapoo Formation strata, along the Red Deer River valley and its tributaries (the type-section of the Paskapoo) into their proper stratigraphic position. The thick, predominantly massive, cliff-forming, buff-weathering, conglomeratic sandstones normally identified as Paskapoo Formation are hereby termed the Haynes Member. Strata of the lower part of this member outcrop at Ardley Bend and Dry Island Buffalo Jump along the Red Deer River valley. Overlying these conglomeratic sandstones, argillaceous and carbonaceous (coaly) strata are designated the Lacombe Member. These strata occur as isolated outcrops upstream from Joffre Bridge along the Red Deer and Blindman river valleys, and comprise the majority of bedrock west to the disturbed belt.

Adjacent to the Alberta Foothills near Hinton, strata of the Obed-Marsh coal zone are hereby termed the Dalehurst Member (type-section: Union Oil Company of Canada Limited Coal Exploration Corehole 76-54). Uppermost strata of this member are the youngest of the Paskapoo Formation. The lower part of this member may be correlative in part to uppermost strata of the Lacombe Member in the Red Deer-Lacombe area. Strata of the Dalehurst Member are restricted to the area immediately adjacent to the Alberta Foothills.


Les strates de la formation Paskapoo dans les plaines centrales de l'Alberta peuvent etre subdivisees en trois membres sur base d'une etude de ces couches dans le sous-sol et an affleurement dans les regions de Red Deer-Lacombe et Obed-Marsh. Deux sections de subsurface (carottes d'exploration charbonniere 2-82 et 3-82 de l'Alberta Research Council) dans la region de Red Deer-Lacombe fournissent des sequences ininterrompues des strates de la formation Paskapoo dans cette region. Ces sections sont ici appelees sections de reference principales, et contiennent les sections-types des membres nouvellement proposes de Haynes et Lacombe. Ces sections de reference principales permettent de placer dans leur position stratigraphique correcte les affleurements isoles des couches de la formation Paskapoo le long de la vallee de la Red Deer River et de ses affluents (section-type de la formation Paskapoo). Les gres conglomeratiques epais, principalement massifs, formant des escarpements, et d'alteration jaune clair, normalement rattaches a la formation Paskapoo, sont ici attribues au membre Haynes. Les strates de la partie inferieure de ce membre affleurent a Ardley Bend et a Dry Island Buffalo Jump dans la vallee de la Red Deer River. Les couches argileuses et carbonees (charbonneuses) qui couvrent ces gres conglomeratiques forment le membre Lacombe. Ces couches forment des affleurements isoles en amont de Joffre Bridge le long des vallees de la Red Deer River et de la Blindman River, et comprennent la majorite des roches presentes vers l'ouest jusqu'a la chaine perturbee.

Les strates de la zone charbonneuse d'Obed-Marsh, adjacentes aux contreforts de l'Alberta pres de Hinton, sont ici appelees le membre Dalehurst (section-type : carotte d'exploration charbonniere 76-54 de l'Union Oil Company of Canada). Les couches superieures de ce membre sont les plus jeunes de la formation Paskapoo. La partie inferieure de ce membre pourrait en partie etre correlee avec les strates superieures du membre Lacombe dans la region de Red Deer-Lacombe. Les couches du membre Dalehurst sont limitees a la region immediatement adjacente aux contreforts de l'Alberta.

Traduit par Patrice de Caritat

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