Depositional History and Petroleum Potential of the Middle Devonian Fort Vermilion Formation, Alberta
Date
2023-11-20
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Abstract
The Devonian Fort Vermilion Formation in the Swan Hills area of Alberta comprises interbedded anhydrite and carbonates. Generally interpreted as being formed subaerially in a sabkha environment, a new depositional model is proposed for this unit whereby sedimentation occurred subaqueous in a protected, variably deep, restricted basin. Based upon core examination, petrography, and various geochemical analyses, four facies assemblages representing four environments were identified: restricted and hypersaline, early diagenetic, moderately restricted, and euhaline. Three models, differing primarily on scale and proximity to the marine environment are discussed; these are: i) salina; ii) restricted lagoon; and iii) lake. The evidence garnered through this study are most consistent with deposition in a hypersaline lagoon setting, cut off from the open marine environment. Early deposition was most restricted with fluctuating water chemistry resulting in the deposition of carbonate and evaporite units. Seawater and associated ions were supplied to the system via evaporative drawdown through a seaward barrier or tidal channels. Relative sea level rise resulted in a better connection with the open ocean and the end of evaporite deposition, though salinity-restricted conditions persisted, as demonstrated by a paucity of marine biota. Following further sea level rise normal marine conditions ensued. The petroleum potential of the Fort Vermilion Formation was also investigated, though it was determined that the absence of organic matter (indicated by very low TOC values) prevented the generation of any substantial amount of hydrocarbons.
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Keywords
Devonian, Fort Vermilion, carbonate, evaporite
Citation
Heath, D. P. (2023). Depositional history and petroleum potential of the Middle Devonian Fort Vermilion Formation, Alberta (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.