New Insights into natural carbonation of ultramafic rocks in the Sultanate of Oman

Muscat, Oman — New research published in the Geological Society of America Bulletin reveals how  fluids naturally carbonate ultramafic rocks formed within Oman’s Samail Ophiolite, providing new insight into tectonic processes and natural carbon sequestration.

The study focuses on listwaenite, a carbonate-altered ultramafic rock formed when carbon-bearing fluids react with mantle rocks. Through detailed geological mapping in the Fanja area of the Eastern Oman Mountains (including a detailed geological map at a scale of 1:10,000), researchers examined the structural controls that enabled large-scale carbonation.

Results show that carbonation occurred during shallow crustal extension, when brittle faulting created pathways for carbon-rich fluids to circulate through ultramafic rocks. This finding challenges earlier interpretations that linked these rocks primarily to deep subduction environments.

The team identified two generations of listwaenite. The older generation formed along low-angle normal faults that overprinted earlier thrust structures, while the younger generation developed along later steep-dipping extensional and strike-slip faults. These structures reflect a complex tectonic history involving post-obduction extension, plate interactions, and regional uplift.

Beyond reconstructing Oman’s geological evolution, the study highlights the importance of fault systems in facilitating mineral carbonation. Naturally carbonated ultramafic rocks provide a valuable natural analogue for long-term carbon storage in solid minerals, offering insights relevant to future geological carbon sequestration strategies.

The findings underscore the role of tectonics in controlling fluid flow and mineral transformation within Earth’s crust.