Mineralogical variation and elemental distribution within a natural carbonation cement sequence (Sverrejfellet, Svalbard): results and implications

The natural carbonation of basalts has been extensively studied in recent years, as it helps us understand how this process develops and the factors that influence it, particularly in various geological settings and with respect to element mobility. The natural analog of Sverrefjellet in Svalbard remains largely unexplored, yet it presents an intriguing case due to its unique mineralogy. This study aims to correlate petrography, X-ray diffraction (XRD) results, scanning electron microscopy (SEM), cathodoluminescence, and elemental composition in order to gain insights into the mechanisms behind the carbonation sequence of basaltic rocks from the Sverrefjellet volcano in Svalbard.

Sverrefjellet, which erupted about one million years ago, consists of cinder cones, pillow lavas, and dikes formed under subglacial conditions (Treiman 2012). According to Pierozzi et al. (2025), the carbonate cement formed in relation to the alkali basalts of the volcano results from the carbonation process. These findings and new data from the carbonate cement can provide valuable insights into the sample's composition and evolution, the influence of the basaltic host rock, and the environmental conditions during carbonation. The carbonate cement sequence primarily consists of calcite-type carbonates within the magnesite-calcite-siderite compositional range. Various stages of carbonation are evident in the cements, indicating a shift in crystal chemistry from calcian proto-dolomite to Ca-poor magnesite, ultimately leading to a mixture of Fe-rich carbonates (siderite) and non-carbonate cements.

Throughout these stages, distinct behaviors of minor and trace elements are observed, revealing the conditions of the system during cement development. The findings emphasize the significant influence of the host rock's geochemistry on the composition and evolution of carbonate cements.

Treiman, A. H. (2012) ‘Eruption age of the Sverrefjellet volcano, Spitsbergen Island, Norway’, Polar Research. Norwegian Polar Institute, 31

Pierozzi, A., Faulkner, N., Szucs, A. M., Terribili, L., Maddin, M., Meloni, F., Devkota, K., Zubovic, K. P., Guyett, P. C., & Rodriguez-Blanco, J. D. (2025). Natural carbonation in alkali basalts: Geochemical evolution of Ca–Mg–Fe carbonates at Sverrefjellet, Svalbard. Carbon Capture Science & Technology, 17, 100510. https://doi.org/10.1016/j.ccst.2025.100510