ABSTRACT: Sequence Stratigraphy: A Unifying Model for Interpretation of the Carbonate Sediments of the Beaverhill Lake Group, Alberta, Canada

POTMA, KEN, M. GILHOOLY, J. WEISSENBERGER, and P. WONG, Esso Resources Canada, Ltd., Calgary, Alberta, Canada

Sequence stratigraphy offers a unifying template for interpreting and predicting stratal patterns in the carbonates of the Beaverhill Lake Group of the Alberta subsurface. Three third-order sequences are recognized: a Slave Point sequence, a lower Swan Hills sequence, and an upper Swan Hills sequence.

The Beaverhill Lake Group, expanded somewhat here to include the Gilwood and Cooking Lake formations, forms the base of a second-order Middle to Upper Devonian transgressive-regressive sequence. As a result, the third-order sequences that make up the group are predominantly transgressive.

The Slave Point sequence has a major sequence boundary at its base upon which the fluvio-deltaic clastics of the Gilwood Formation were deposited. The upper portion of the sequence contains the Slave Point platformal carbonates. The lower Swan Hills sequence contains the prolific Swan Hills Formation reef complexes above a minor sequence boundary. The reef complexes are shown to be time equivalent to the encasing Waterways Formation shales. An upper Swan Hills sequence, which includes the lower part of the Cooking Lake Formation, also has a minor sequence boundary at its base.

Core data, combined with regional well-log cross sections, can be used to identify the sequences and correlate them on a pool and regional basis. The model explains many of the observed stratal patterns within the sequences and proposes causal mechanisms for their occurrence. These sequence-keyed interpretations can result in an improved understanding of reefal evolution.

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