Secondary Mineralization in Flow-Tops of Columbia River Basalts: Implications for the Sequestration of Anthropogenic Carbon

By Courtney Porter

Whitman College, Walla Walla WA

 

Carbon dioxide is a greenhouse gas that absorbs the infrared spectrum of light, heating the Earth’s troposphere. A technique to keep carbon dioxide out of the atmosphere is the capture and sequestration of anthropogenic carbon. Ongoing pilot projects investigate CO2 sequestration by injecting carbon dioxide as supercritical fluid into geologic formations.  One form of carbon sequestration is in situ mineralization, where carbon dioxide reacts with minerals in basalt to create stable calcite (CaCO3) minerals. Currently research is being done on mineral carbonation in continental flood basalts by Pacific Northwest National Laboratories (PNNL) in Richland, Washington. PNNL seeks to inject carbon dioxide into deep aquifers, which occur in the tops of flows. This study identifies secondary minerals that filled void space in the basalts because clinoptilolite, celadonite, silica-oxides, and calcite may act as a barrier or promote reaction between the carbon dioxide and the host basalt. Chemical modeling of these potential reactions gives insight into the direction these reactions may occur. These results suggest that chemical reactions do not occur at the desired temperature and pressure, but further computer modeling is necessary for a full conclusion.