Open File Report 1985-02

Open File Report 1985-02

OFR 1985-02

Delineation of the Northern Extension of the Rimbey-Meadowbrook Reef Tract, Upper Devonian Northeastern Alberta

Author(s) Ing, A. Date 1985-01-01

The Rimbey-Meadowbrook-Leduc reef chain is a well-defined SSW-NNE linear trend which is made up of individual Upper Devonian Leduc Formation reefs. This linear trend can be recognized from Tp 35 to Tp 95 and is located in the subsurface of central Alberta.

The reefs are localized on topographic highs along the western margin of the Cooking Lake Formation platform and are surrounded by argillaceous limestones and calcareous shales of the Duvernay and Ireton Formations. The buildups are directly overlain by Ireton shales but in one case, appears to be directly overlain by Grosmont Formation platform carbonates.

The thickness of the reefs varies from 90 m in the north to 200 m in the south. One factor which restricted the vertical development of the Leduc reefs in the northern portion of the reef tract was the westward progradation of the Grosmont Formation. The prograding Grosmont front encroached on the Leduc reefs and inhibited further reef development earlier in the north than in the south. As a result, the reefs are thinnest towards the north, thicken gradually southward, and are the thickest beyond the southern depositional edge of the Grosmont Formation.

Ing, A. (1985): Delineation of the northern extension of the Rimbey-Meadowbrook reef tract, Upper Devonian northeastern Alberta; Alberta Research Council, ARC/AGS Open File Report 1985-02, 29 p.