--> Abstract: Facies Relationships and Stacking Patterns of Valley-Fill Deposits in the Viking Formation, Central Alberta: Examples of Tripartite Facies Zonations, by S. A. J. Pattison; #91012 (1992).

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ABSTRACT: Facies Relationships and Stacking Patterns of Valley-Fill Deposits in the Viking Formation, Central Alberta: Examples of Tripartite Facies Zonations

PATTISON, SIMON A. J., Esso Resources Canada Ltd, Calgary, Alberta, Canada

Valley-fill deposits occur at Crystal, Sundance, Edson, Cyn-Pem, and Willesden Green. The valley-fill sand bodies are bounded above and below by erosion surfaces. The lower erosion surface is symmetrical in cross section, slightly sinuous in plan view, oriented northeast to southwest, perpendicular to the trend of the shoreface deposits (e.g., Gilby-Joffre), and is labeled the VE2 erosion surface. This surface was cut during the "VE2" lowstand, which might be time correlative with the 98 Ma eustatic fall of sea level.

The valley-fill deposits rest within the VE2 scour, are 10-35 m thick, and consist of interbedded mudstones, sandstones, and conglomerates. These sediments were deposited into the valleys during

various phases of the ensuing "VE3" transgression. This transgression was punctuated by stillstands and a minor regression, the latter of which led to the re-incision in the Crystal valley and a basinward shift in facies.

Tripartite facies geometries (sand-mud-sand) are observed in the valley-fill deposits at Crystal, Sundance, and Edson. Delta front or bay head delta sandstones occur in the landward portion of the valley, estuarine mudstones occur in the central part of the valley, and bioturbated marine sandstones occur in the seaward portion of the valley. Fluctuations in relative sea level have caused both landward (e.g., Sundance and Edson) and seaward (e.g., Crystal) shifts of the tripartite facies zones. The large-scale internal architecture of the valley-fill deposits is dominantly controlled by fluctuations in relative sea level.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)