Basalt-CO2-H2O Interactions and Variability in Carbonate Mineralization Rates
Flood basalts are receiving increasing attention as possible host formations for geologic sequestration of anthropogenic CO2, with studies underway in the U.S., India, Iceland, and Canada. Our previous laboratory studies with Columbia River basalts showed relative quick precipitation of carbonate minerals compared to other siliclastic rocks when batch reacted with water and supercritical CO2. In this study, our prior work with Columbia River basalt was extended to tests with basalts from the eastern U.S., India, and Africa. The basalts are all similar in bulk chemistry and share common minerals such as plagioclase, augite, and a glassy mesostasis. Single pass flow through dissolution experiments under dilute solution and mildly acidic conditions indicate similar cation release behavior among the basalt samples tested. Despite similar bulk chemistry and apparent dissolution kinetics, long-term static experiments with CO2 saturated water show significant differences in rates of mineralization as well as precipitate chemistry and morphology. For example, basalt from the Newark Basin in the U.S. is by far the most reactive of any basalt tested to date. Carbonate reaction products for the Newark Basin basalt were globular in form and contained significantly more Fe than the secondary carbonates that precipitated on the other basalt samples. Calcite grains with classic “dogtooth spar” morphology and trace cation substitution (Mg and Mn) were observed in post-reacted samples associated with the Columbia River basalts. Other basalts produced solid precipitates with compositions that varied chemically throughout the entire testing period. Polished cross sections of the reacted grains show precipitate overgrowths with irregular regions outlined by dark and bright layers indicative of zonations of different compositions. For example, SEM-EDX analysis across carbonate precipitates, which resulted from 854 days of reaction of the Central Atlantic Mafic Province (CAMP) basalt with CO2 saturated water showed distinct chemical regions. Composition of dark colored regions was dominated by a CaCO3 end-member composition, whereas the bright regions were chemically closer to an FeCO3. Chemical differences in the precipitates indicate changes in fluid chemistry unique to the dissolution behavior of each basalt sample reacted with CO2 saturated water.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 977337
- Report Number(s):
- PNNL-SA-62986; AA3010000; TRN: US201013%%476
- Resource Relation:
- Conference: Energy Procedia, 9th International Conference on Greenhouse Gas Control Technologies , 1(1):4899-4906
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
ANORTHOSITES
BASALT
CALCITE
CARBONATE MINERALS
CARBONATES
CATIONS
CHEMISTRY
COLUMBIA RIVER
CROSS SECTIONS
DISSOLUTION
FLOODS
GREENHOUSE GASES
KINETICS
MINERALIZATION
MORPHOLOGY
PRECIPITATION
TESTING
WATER
CARBON DIOXIDE
carbon sequestration
mineralization
geologic sequestration