- 1Leibniz IOW, Geochemistry & Isotope Biogeochemistry, Warnemünde, Germany (michael.boettcher@io-warnemuende.de)
- 2Geography and Geology, University of Greifswald, Germany
- 3Interdisciplinary Faculty, University of Rostock, Germany
- 4College of Material Science and Engineering, Guizhou Minzu University, PRC
- 5Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, PRC
Double carbonates of the norsethite-family (Ba(Mg,Mn,Fe)[CO3]2) are used as crystal chemical and geochemical analogues for the prominent rock-forming mineral dolomite (CaMg[CO3]2) and the less common kutnahorite (CaMn[CO3]2). Selected family members have been observed to occur in low- and high-temperature natural systems, like Baltic Sea sediments or different types of ore deposits. For most of the norsethite-members, neither the thermodynamic nor the reaction kinetic properties are well constrained or even known, so far.
In the present study, the dissolution behaviour of double and triple carbonate members of the norsethite family were dissolved in CO2-saturated solutions at 25°C and 1 atm total pressure. The carbonates were synthesized at high P and T and characterized as described by Liang et al. (2021, 2025) and Böttcher et al. (2022). Free-drift batch-type reactors were used. Both, the congruent and incongruent parts of the dissolution process were investigated and the partitioning of metals and stable carbon isotopes was followed. At the end of the experiment, carbonate solid-solutions were precipitated by letting CO2 to degas.
The dissolution in aqueous solutions was found to be initially congruent with respect to metal stoichiometry. The solution composition was interpreted using PHREEQC. Extrapolation of experimental congruent reaction parts give the solubility product and the free energy of formation of the respective carbonate and the time-dependent reaction path allows for the extraction of dissolution kinetic parameters. The development of 13C contents of dissolved inorganic carbon represent an experimental verification of carbonate dissolution in a system open with respect to a CO2 gas phase (sensu Garrels & Christ, 1965 and Deines et al., 1974).
These new experimental results form a base to include these phases into modelling codes for natural or underground CO2-storage systems.
How to cite: Böttcher, M. E., Haršányi, A. S., Dellwig, O., Grathoff, G., Schmiedinger, I., and Liang, W.: Thermodynamic stability and reactivity of dolomite-analogues from the norsethite-family: Carbon isotope and metal release during experimental dissolution at 25°C and 1 atm total pressure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12689, https://doi.org/10.5194/egusphere-egu25-12689, 2025.
