A multidisciplinary approach for evaluation of in-situ CO2 mineralization potential of anorthosite formations

This study provides the first integration of structural characterization and reactivity experiments applied to anorthosite formations for CO₂ mineralization assessment and outlines a framework that can be applied to other anorthosite bodies. Successful mineral sequestration requires two factors: 1) sufficient reactivity of the subsurface rocks and 2) fluid flow pathways for the injection and subsurface transport of pure or water-dissolved CO2. To assess the potential of mineral sequestration in massive anorthosites, we focused on the Khamal anorthosite batholith. This anorthosite is located near major CO₂ emission sources located in Yanbu, western Saudi Arabia. The reactivity of this batholith was tested by reacting ground cleaned batholith samples in aqueous Na₂CO₃ and NaHCO₃ solutions in batch reactors at 60 °C. Elemental analysis, scanning electron microscopy, and saturation index calculations based on aqueous geochemical data obtained from the experiments indicate substantial calcium carbonate formation can be attained. Unmanned Aerial Vehicle photogrammetric mapping of the batholith revealed its lithologies, faults and fractures. Notably, this detailed structural assessment identified a fracture corridor along a Tertiary fault cutting across the batholith that likely provides sufficient permeability for the injection of significant quantities of water dissolved CO₂ into the anorthosite. The success of this approach can be transferred to exploit the carbonation potential of other massive igneous bodies worldwide.