ABSTRACT: Thermal History of the Peace River Arch Region, Western Canada Sedimentary Basin: Constraints from Apatite Fission Track Data

ISSLER, D. R., Geological Survey of Canada, Calgary, Alberta, Canada, and S. D. WILLETT, C. BEAUMONT, A. M. GRIST, and R. A. DONELICK, Dalhousie University, Halifax, Nova Scotia, Canada

Fifty-seven apatite mineral separates, obtained from Cretaceous, Paleozoic, and Precambrian petroleum exploration drill core samples from the northern part of Western Canada sedimentary basin were analyzed for their fission track age and etchable track length distributions. The samples were collected along an east-west transect centered on the Peace River arch and extending between the Alberta/Saskatchewan and Alberta/British Columbia borders. All samples experienced partial to total annealing of fission tracks during past burial at higher temperatures. A systematic westward decrease in sample fission track age, irrespective of stratigraphic age, corresponds with the observed westward stratigraphic thickening toward the foothills. Among westernmost samples, those that experienced eith r nearly complete or total annealing and resetting of the fission track clock provide important constraints on the timing of maximum temperature.

Statistically valid time-temperature histories were calculated from measured fission track parameters using a constrained random search inversion technique. These results, when interpreted in conjunction with vitrinite reflectance data and stratigraphic reconstructions, suggest that paleogeothermal gradients increased progressively eastward across the basin. This distribution is consistent with heat transport by large-scale, regional groundwater flow. However, samples near the Alberta/British Columbia border are more annealed than expected, implying that burial was deeper or geothermal gradients were higher than initially assumed.

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