--> Abstract: Middle Triassic Sequence Biostratigraphic Framework, Foothills Region of Northeastern British Columbia: Outcrop-Subsurface Correlation & Significance for Hydrocarbon Exploration, by John-Paul Zonneveld and Thomas F. Moslow; #90914(2000)

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John-Paul Zonneveld1, Thomas F. Moslow2
(1) University of Calgary, Calgary, AB
(2) Ulster Petroleums Ltd, Calgary, AB

Abstract: Middle Triassic sequence biostratigraphic framework, Foothills region of northeastern British Columbia: outcrop-subsurface correlation & significance for hydrocarbon exploration

The Middle Triassic (Doig, Halfway and basal Charlie Lake Formations) is one of the most economically important stratigraphic intervals within the northwestern Western Canada Sedimentary Basin. These units comprise a complex succession of marine and marginal marine siliciclastic, carbonate, and evaporite sediments deposited on the western margin of the North American Craton. Although detailed sedimentologic models have been proposed for these units in several producing gas fields in the plains area a large area exists in the eastern foothills/western plains region where information is lacking.

The Toad and Liard Formations comprise the outcrop equivalent of the Doig-Halfway-basal Charlie Lake interval. Extensive outcrop sections of these units have supplied a template for correlating units within the subsurface and have provided a basis for developing a regional sequence biostratigraphic framework. Detailed sequence biostratigraphic and sedimentologic modelling of these units as well as generation of detailed outcrop gamma profiles has facilitated correlation with the subsurface as well as aided in resolving the lithologic composition of uncored intervals in the subsurface.

The Middle Triassic interval in northeastern British Columbia comprises three sequences bound by 2nd and 3rd order sequence boundaries. Surfaces bounding systems tracts (sequence boundaries, transgressive and maximum flooding surfaces) display characteristic gamma signatures and are invaluable surfaces in correlation between the outcrop belt and wells in the subsurface to the east. Several horizons, including a thin, regionally extensive, transgressive bioclastic sandstone within the medial sequence, have been dated precisely using biostratigraphy and have been correlated throughout the basin.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana