Origin of Lithium and Other Alkali Metals in Devonian Brines of Alberta

The increasing demand for electrified transportation and the need for energy storage solutions to support intermittent renewable energy generation, such as solar and wind power, have sparked significant interest in essential critical minerals and metals, including lithium (Li). Traditional battery technologies rely heavily on lithium, and alternative sources, such as the oil brines of the Alberta Basin, are now being considered more than ever before due to economic improvements in Li extraction methods and reduced environmental impacts when compared to traditional technologies such as hard rock mining and salar evaporation ponds. Therefore, these brines have the potential to become a sustainable and accessible option for battery manufacturers in North America. To explore this mineral development opportunity further, the Alberta Geological Survey (AGS) conducted a comprehensive brine sampling program in collaboration with oil and gas industry operators. Previous studies evaluated the occurrence of lithium in Devonian brines of Alberta; however, there is still much to understand about the origin, accumulation, and transport mechanisms of this metal in the Alberta Basin. The chemistry of these brines provides evidence of processes involved in the removal, transport, and accumulation of lithium. Identifying these processes is crucial for developing known existing deposits and locating new areas that have not been explored by oil and gas wells but may contain economically viable lithium concentrations.

For this study, 178 Devonian brine samples were investigated, representing a subset of 288 samples reported from the 2021–2024 AGS brine sampling program. In addition, AGS selected 81 Devonian samples from previous publications based on the availability of isotopic and halogen data to complement the dataset. The samples were collected from the Granite Wash, Keg River Formation, Gilwood Member of the Watt Mountain Formation, Beaverhill Lake Group (including Swan Hills and Slave Point formations), Cooking Lake, Leduc, and Nisku formations, and the Wabamun Group. Given the complex history of these brines, conservative species were analyzed to gather geochemical information while accounting for the effects of evaporation, diagenesis, mixing, precipitation, dissolution, and reprecipitation. Apart from major ions and dissolved metals, the analysis included halogens (chlorine and bromine), alkali metals (rubidium, cesium, lithium, potassium, and sodium), and isotopes of oxygen (δ18O), hydrogen (δ2H), lithium (δ7Li), boron (δ11B), sulphur (δ34S), and strontium (87Sr/86Sr). 

The Devonian brines of the Alberta Basin can be classified into two primary groups: Lower–Middle Devonian and Middle–Upper Devonian. The differentiation between these groups is based on their distribution of δ2H and δ18O values and their rubidium/cesium molar ratios. Additionally, their δ7Li and δ11B compositions indicate that Li may have been adsorbed from seawater and accumulated within fine-grained marine sediments that may have also been enriched in Li. The 87Sr/86Sr values derived from these samples reveal the migration paths taken by these Li-enriched fluids, which may have been expelled from clays and other fine-grained lithologies during the Laramide orogeny and were subsequently mixed with residual evaporitic brines and low Li fluids related to the basement. These brines have undergone further alterations due to diagenetic processes, evaporation, water-rock interactions, and different degrees of mixing with meteoric waters.
This work was completed under the Mineral Grant provided by the Government of Alberta on June 22, 2021.