The permanent disposal of CO2 in the subsurface has been considered a viable mitigation option to reduce global warming. CO2 is injected and permanently stored through different trapping mechanism in porous rocks at depths greater than 800 meters. Continental flood basalts are considered unconventional CO2 storage reservoirs where interbedded massive basalt zones serve as barriers for upward CO2 migration. However, vertical joints and sub-vertical fractures in those massive basalt zones may serve as conduits for buoyancy-driven CO2 migration and thereby pose a risk to CO2 containment. The objective of this study is to determine whether mineral precipitation will seal joints and fractures during the vertical migration of CO2-enriched water and thereby contribute to CO2 containment. Interactions of CO2-enriched water with basalt powder, wafers, and artificially fractured core samples were studied in experiments at different temperature and pressure conditions representing various depths. At pressure and temperature conditions representing a depth of ≈800m only Mg, Fe and Si were mobilized presumably due to olivine dissolution while at conditions of ≈1200 m also Ca was released presumably from pyroxene dissolution. Smectites, zeolites, Fe-oxides, and magnesium-rich carbonate were observed as secondary minerals on the basalt wafers at conditions representing a depth of 800 m, which is in agreement with calculated mineral saturation indices. Precipitation exceeded dissolution by volume leading to a net porosity reduction by 1 % in incubations over 85 days. Our result suggests these secondary minerals could be potential sealants and mitigate CO2 leakage pathways contributing to the containment of CO2 in these particular formations.