In situ carbon storage potential in a buried volcano

In situ mineral carbonation in porous and permeable mafic and ultramafic volcanic rocks is proposed to be a promising process that can contribute toward safe and permanent CO₂ sequestration. Here, we investigated a partially buried Late Cretaceous composite volcano located offshore the central West Iberian margin as a proxy for potential in situ mineral carbonation in volcanic edifices on continental margins worldwide. Based on seismic data, geochemistry, and petrophysical properties, deterministic scenarios for permanent carbon storage were estimated. Overall analysis of the nature of the volcano and its internal architecture revealed that this single edifice has the potential to store 1.2–8.6 Gt CO₂ in newly formed carbonate mineral assemblages. Results suggest that ancient, buried volcanoes on continental margins constitute auspicious sites for safe carbon storage, with a total storage capacity of hundreds of gigatonnes of CO₂.