Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8850178 | Chemie der Erde - Geochemistry | 2018 | 7 Pages |
Abstract
Carbonates formed from hyperalkaline aqueous solutions at the EarthÌs surface are known to bear the most extreme disequilibrium isotope signatures reported so far in nature. We present here the results for stable carbon (C), oxygen (O), and barium (Ba) isotope fractionation during the precipitation of witherite (BaCO3) induced by the chemical absorption of atmospheric carbon dioxide (CO2) into an aqueous hyper-alkaline solution (at 4° and 21â¯Â°C; 1â¯atm total pressure). Independent from temperature, the barium carbonate formation was associated with a substantial enrichment of the lighter C and O isotopes in the solid compared to the atmosphere (C, O), close to previous results found in experiments and nature. A new approach is introduced to explain oxygen isotope fractionation upon hydroxylation of CO2. With Ba isotope enrichment factors between â0.45 and â0.53â° (138/134ε) or â0.34 and â0.40â° (137/134ε), respectively, the synthesized BaCO3 displays the highest kinetic enrichment of the light Ba isotope in the carbonate solid reported so far.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Michael E. Böttcher, Nadja Neubert, Peter Escher, Katja von Allmen, Elias Samankassou, Thomas F. Nägler,