Experimental study of Mg-rich silicates carbonation at 400 and 500 degrees C and 1 kbar | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS


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  Experimental study of Mg-rich silicates carbonation at 400 and 500 degrees C and 1 kbar

Type de publication:

Journal Article


Chemical Geology, Volume 265, Ticket 1-2, p.79-87 (2009)



Numéro d'accès:





UMR 7154 ; Physico-chimie des fluides géologiques ; N° Contribution : 2383 ; CO2 sequestration; Mineral carbonation; Ultrabasic rocks; Carbonates


The reactivity of olivines, orthopyroxenes and serpentines (chrysotile) with CO2 rich fluids was experimentally studied at 400-500 degrees C and 1 kbar (+/-NaCl). Levels of formation of solid carbonate phases were measured both by analysing the recovered gas phase and by step heating of the solid samples. Carbonation levels of several percents per hour (from 3 to 57% in 4 h depending upon experimental conditions) were measured with increasing efficiency in the order: orthopyroxene, chrysotile, olivine. In the case of olivine, a positive impact of water fugacity and salinity on carbonation levels was evidenced. Microstructures of the samples showed that the carbonation reaction proceeded by dissolution/precipitation. A coupling between solid carbonate production, mostly as magnesite, and olivine serpentinisation was demonstrated. Isotopic compositions of carbon in gas phases and carbonates were measured. They were found to be consistent with mass balance calculations, additionally suggesting the existence of an accessory carbon-bearing phase carrying negative C-13 signatures. This phase was identified by transmission electron microscopy, as an ill ordered graphite phase, which would account for about 15% of carbon mineral under these conditions. (C) 2009 Elsevier B.V. All rights reserved.


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