Regional Cross-Sections of Devonian Stratigraphy in Northeastern Alberta (NTS 74D, E)

In this report, we present three regional cross-sections of the Devonian in subsurface along east-west and north-south trend lines in a study area encompassing Twp. 87 to 98, Rge. 3 to 15, W 4th Mer, Alberta. This work was part of the Energy Resources Conservation Board Oilsands Caprock Integrity Project (OSCRIP). Devonian strata are included in OSCRIP to understand both the structure of Devonian strata, with emphasis on the effects from the dissolution of Prairie Evaporite Formation strata, and the nature of the sub-Cretaceous unconformity.

Devonian stratigraphy in northeastern Alberta was affected by dissolution of evaporites of the Prairie Evaporite Formation, the collapse of post-Prairie Evaporite Devonian strata, and erosion prior to the deposition of the Cretaceous McMurray Formation. The resulting topography of the sub-Cretaceous unconformity surface influenced the thickness distribution of the Lower McMurray Formation. Dissolution-related subsidence likely continues locally to the present day, but its timing, distribution, and effect on overlying strata are not well understood.