Mechanistic Investigation of CO ₂ Mineralization Potential in the Ultramafic Lithology of Deccan Traps

The increasing atmospheric carbon dioxide concentrations underscore the need for reliable sequestration mechanisms. Mineralization in mafic rocks is a promising and viable option due to the presence of calcium- and magnesium-bearing reactive minerals. In this study, we evaluated the CO 2 sequestration potential and reaction pathways of the tephrite–basanite rock from the Aurangabad Basin in India. We characterized the rock mineralogy and performed a CO 2 mineralization experiment in a reactor and, consequently, conducted CHNS and ICP–MS analysis on the post-CO 2 experiment sample to evaluate the sequestration potential and effluent chemistry. We also conducted PHREEQC geochemical modeling on the mineral assemblage to investigate the mineralogical changes and CO 2 sequestration potential under various pressure and temperature conditions. The XRF data indicated 11.04 wt % CaO and 2.99 wt % MgO in the sample, and the XRD analysis revealed a mineralogical composition of 65.4% anorthite, 17.4% enstatite, and 17.2% diopside as the primary mineral phases. Powdered rock samples exhibited increasing CO 2 uptake with increasing pressure in the batch experiments, with corresponding pH trends in deionized water reflecting the same reactivity pattern. PHREEQC simulations revealed that increasing the temperature promoted the transformation of diopside and anorthite into calcite and dolomite, which are stable carbonate minerals. The experimental results indicated a short-term CO 2 uptake of 4.83–22.49 kg/m 3, mainly due to dissolution and early carbonation, whereas geochemical modeling predicts long-term mineralization potential ranging between 7.2 and 13.22 kg/m 3 after 10 years. Furthermore, the Monte Carlo simulation for storage potential suggests that the theoretical storage potential in the Deccan Volcanic Province may range from 9.31 to 29.97 GtCO 2 based on laboratory-derived storage efficiencies, which represents an upper bound geological estimate.