Alexandria Engineering Journal (Apr 2022)
Geological features and occurrence conditions of dawsonite as a main Carbon-Fixing mineral
Abstract
Dowsonite, as the main carbon-fixing mineral, is an orthorhombic carbonate mineral containing water, sodium and aluminum. The carbon capture of dawsonite in the reservoir rocks accounts for 42.2%-90.1% of the total carbon sequestration. Dawsonite is widely distributed across the globe, especially in Europe and Asia. Dawsonite mostly occurs in Permian, Triassic, Cretaceous, and Paleogene formations, and exists in the medium to shallow layer of 1,000–2,200 m. The dawsonite found worldwide has three main occurrences: metasomatism, cementation, and filling. The former two are more common than the last type of occurrence. The dawsonite stems from two major sources: inorganic and organic. The inorganic origins include magmatic activity, and the dissolution or pyrolysis of carbonate rocks. Most of the dawsonites found worldwide are of inorganic origin, mainly due to magmatic activity, and only a few are due to the dissolution or pyrolysis of carbonate rocks. The formation of dawsonite is affected by various factors, such as precursor mineral, rock type, pH, and the partial pressure of carbon dioxide (CO2). Multiple minerals, namely, plagioclase, sodium feldspar, potassium feldspar, montmorillonite, and mica, can serve as the precursor minerals of dawsonite. Among them, plagioclase is the most favorable precursor mineral for the formation of dawsonite. Dawsonite occurs in a wide range of rock types, and feldspar sandstone is the best rock type for dawsonite. Natural dawsonite forms under the temperature range of 25-200 °C, while artificial dawsonite can be synthetized under 60-180 °C. The dawsonite dissolves at about 150 °C. Most evidences suggest that dawsonite is formed and tends to be stable in an alkaline environment. But some scholars argue that dawsonite is formed in a neutral-weakly acidic fluid environment. It is generally agreed that that dawsonite is formed under high CO2 partial pressure. Dawsonite is not only a tracer mineral of CO2 [1], but also the main carbon-fixing mineral for underground CO2 storage.
