Reid, Scott A.1, George Pemberton2
(1) University of Alberta, Sherwood Park, AB
(2) University of Alberta, Edmonton, AB
ABSTRACT: Ichnology and Sedimentology of the Doe Creek Member of the Kaskapau Formation: The Importance of Recognizing the Nature of Fully Marine Trace Fossil Suites
The Cenomanian Doe Creek Member comprises sand-dominated units within the Kaskapau Formation shale. The sandstones are of reservoir quality and have been estimated to host crude oil reserves of 460 million barrels (100 million barrels initial established reserves). This study focuses primarily on the Valhalla Field and its periphery in northwestern Alberta on the southern flank of the Peace River Arch in the Western Canada Sedimentary Basin.
The Doe Creek Member sandstones are sedimentologically complex, with polygenetic origins from both fully marine and brackish environments. Thus, a depositional model derived solely from primary sedimentary structures is potentially inadequate. This study focuses on synthesizing sedimentologic and ichnologic data to yield a more comprehensive interpretation.
Doe Creek strata contain both brackish-water and fully marine ichnofauna. The brackish-water assemblage is characterized by: (1) lower diversity, (2) diminutive marine forms (3) simple structures constructed by trophic generalists, (4) domination by a single ichnogenus, and (5) vertical and horizontal ichnofossils common to both the Skolithos and Cruziana ichnofacies. The fully marine ichnofauna comprise a wide variety of traces including spectacular examples of Zoophycos, which provides a stark contrast for the brackish suites present.
The distribution of the fully marine and brackish ichnofacies provides a detailed understanding of the paleogeography of the Doe Creek Member. The resultant depositional interpretation reflects the spatial and temporal relationships between marine and brackish components of the sedimentary system. Moreover, the data is applied to understanding the distribution of reservoir facies and prediction of optimal reservoir quality in the studied interval.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.