CO _<b>2</b> Mineralization of Basaltic Andesite, Picrite, and Tholeiite of Western Deccan Traps

The Deccan Traps, one of the largest continental flood basalt provinces, offer a promising opportunity for geologic CO2 storage. While most of the mineral carbonation experiments have been conducted on Eastern Deccan basalts, those on the Western Deccan lava pile are limited. The lithostratigraphy and chemostratigraphy of the Western Deccan Traps are well defined, presenting a gap in CO2–water reaction know-how for diverse lithologies. In this study, representative samples of picritic basalt, tholeiite, and basaltic andesite were selected from a gamut of 200 samples collected from the Kalsubai Subgroup, Sahyadri Group of the Western Deccan Traps. We conducted carbonation experiments with samples of the three basalt types, as stubs and powders, to understand the factors influencing these reactions. These samples were subjected to react with CO2 + H2O (aqueous) at a constant 50 bar PCO2, with temperatures set at 100 °C and 140 °C, and reaction times varying from 1 to 12 weeks. We identified the dissolution of the samples through changes in the composition of the reacting fluid and identified precipitation by recognizing the formation of new carbonate and other minerals. This evidences of mineral carbonation indicate that, at a given pressure and temperature, picritic basalt and tholeiite exhibit higher carbonation potential than basaltic andesite. Identifying an optimal host rock that allows a better assessment of the carbonation potential in the Western Deccan lava pile is crucial for implementation of geological CO2 sequestration projects.