US EPA

4966510 

Journal Article 

Carbonated serpentinite (listwanite) at Atlin, British Columbia: A geological analogue to carbon dioxide sequestration 

Hansen, LD; Dipple, GM; Gordon, TM; Kellett, DA 

2005 

Yes 

Canadian Mineralogist
ISSN: 0008-4476
EISSN: 1499-1276 

43 

225-239 

10.2113/gscanmin.43.1.225 

WOS:000228386500012 

Listwanite, a carbonate-altered serpentinite commonly associated with gold and mercury mineralization, also represents a natural analogue to CO2 sequestration via in situ carbonation of minerals. The reaction pathways and permeability structure controlling listwanite formation are preserved and exposed at Atlin, British Columbia, where listwanite extends tens of meters into surrounding wallrock. The overall mineralogical transformation is the same as that being considered for industrial sequestration of CO2, In nature, this reaction proceeds via subreactions that are fossilized as spatially distinct zones. Serpentine + olivine + brucite reacted with CO2 to form serpentine + magnesite, then magnesite + talc, and finally magnesite + quartz. These mineralogical transformations are achieved isochemically, except for the volatile species H2O and CO2. Although the first stage of the reaction only accounts for about 5-15% of the carbonation potential of serpentinite, it is very widespread, and therefore may have sequestered a significant portion of the total bound CO2. Moreover, within intact bedrock, the progress of the magnesite + talc reaction generates fracture permeability, which appears to have locally enhanced reaction. The first two reactions combined account for about half of the carbonation potential for serpentinite and have a small associated increase in the volume of solids, which limits porosity loss. They thus hold the greatest promise for in situ mineral carbonation. The carbonation reactions are controlled by the activity of CO2 in the fluid phase. Proponents of industrial mineral-carbonation processes therefore may seek to control the composition of the input gas to preferentially drive carbonation reactions that minimize porosity loss and maximize. permeability generation. Magnetite was progressively destroyed during carbonation, which allowed magnetic susceptibility to be used as a proxy for carbonation-reaction progress. It facilitated the mapping of the permeability structure of these systems and delineated subtle variations in reaction progress that might otherwise have gone unnoticed in the field. 

listwanite; serpentinite; talc; magnesite; CO2 sequestration; permeability; mineral carbonation; silica-carbonate alteration; carbon management; magnetic susceptibility; reaction progress; Arlin; British Columbia