Growth Faulting and Syntectonic Casting of the Dawson Creek Graben Complex: A North American Craton-Marginal Trough; Carboniferous-Permian Peace River Embayment, Western Canada

BARCLAY, J. E., Geological Survey of Canada, University of Calgary, Calgary, Alberta, Canada, F. F. KRAUSE and R. I. CAMPBELL, Calamity Resources, Calgary, Alberta, Canada, and J. UTTING, Geological Survey of Canada, Calgary, Alberta, Canada

The Dawson Creek Graben Complex was a 150 x 300 km, craton-perpendicular trough near the western North America craton margin. Sedimentary infill spanned 100 million years, and this tectonically controlled basin provides a comparison with other craton-marginal troughs or aulacogens, such as the Big Snowy, Uinta, Delaware, and Southern Oklahoma. We suspect that the graben complex was controlled by outboard, Antler-like orogeny and perhaps some strike-slip control. This syntectonic graben infill model provides a basis for developing new structural-stratigraphic plays in this mature basin.

This extensional trough rests on a former basement arch and is centered in the broadly downwarped Peace River embayment. Sediment infill records several graben casting stages beginning with westernmost down-dropping (early Tournaisian), which then extended eastward and was accompanied by an increase in growth-type block faulting (middle Tournaisian to Visean). Subsidence and faulting decay (Visean to Serpukhovian?) was followed by a retreat to western areas and tectonic stabilization (Early Permian).

The complex was an arcuate half-graben, steep to the north, that widened asymmetrically and increased in depth to the west through time. The complex contained a principal half-graben with neighboring satellite grabens; throughout the complex are numerous kilometer-scale horst and graben blocks. The horsts subsided slower than neighboring grabens. This differential subsidence along block-bounding syn- and postdepositional growth-type normal faults controlled formation and bed thickness, as did inter- and intraformational unconformities.

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)