Modelling mineral trapping

Results from equilibrium modelling indicate that the extent of mineral trapping depends strongly on the fugacity of C02. Consequently, the extent of mineral trapping is sensitive to the rate of mineral-brine-C02 reactions relative to the rate of flow and dispersion of C02 away from the site of injection. Reactions must be fast enough to reach carbonate phase saturation before the C02 is overly diluted by outward radial flow, dispersion, and diffusion. The rates of reaction and the factors that influence the rates of reaction must be better constrained. 

Geochemical modeling methods have been used to estimate the amount of CO2 that can be stored in an aquifer by solubility and mineral trapping. Most of the geochemical modeling simulations have been conducted based on the following equation (e.g., Perkins and Gunter 1995 Talman et al. 2000)... 

ABSTRACT Atmospheric carbon dioxide is trapped within magnesium carbonate minerals during mining and processing of ultramafic-hosted ore. The extent of mineral-fluid reaction is consistent with laboratory experiments on the rates of mineral dissolution. Incorporation of new serpentine dissolution kinetic rate laws into geochemical models for carbon storage in ultramafic-hosted aquifers may therefore improve predictions of the rates of carbon mineralization in the subsurface. 

In simple adsorption from aqueous solution, Hg has features in contrast and in common with the base metals. The hydroxy-cation is the active species in the model for heavy-metal adsorption and this also appears to be true for Hg. However, in contrast with Cu, Pb and Zn, the adsorption is less efficient and is strongly inhibited by the formation of halide complexes, as has been shown by Forbes et al. (1974) (Fig. 12-1). These authors also demonstrate that the adsorption of Hg to goethite is effective at pH as low as 4, allowing it to be trapped subsequent to sulphide oxidation. Whilst many minerals in weathered rocks and soils may each adsorb Hg, the relative efficiency of the hydrous iron oxides (Andersson, 1979) implies that these phases will be the dominant host in most exploration samples. However, the soil organic matter is also of importance and, although the association with Hg has been described as adsorption, it seems more... 

Clay occurs naturally and has plasticity when water is added. These clay minerals are phyllosilicates, which have water trapped in the mineral structure by polar attraction [2], The data from these solid models are then used to create a full-sized... 

Ott U (2002) Noble gases in meteorites—trapped components. Rev Mineral Geochem 47 71-100 Owen T. (1986) Update of the Anders-Owen model for Martian volatiles In Carr M, James P, Leovy C, Pepin R (eds) Workshop on the Evolntion of the Martian Atmosphere LPI Tech Report 86-07 31-32. Lnnar Planet Inst, Honston, Texas... 

Nier AO, Hayden JL (1971) A miniature Mattauch-Herzog mass spectrometer for the investigation of planetary atmospheres. Inti J Mass Spectrom Ion Phys 6 339-346 Nier AO, McElroy MB (1977) Composition and stmctuie of Mars upper atmosphere results from the neutral mass spectrometers on Viking 1 and 2. J Geophys Res 82 4341-4349 Ott U (2002) Noble gases in meteorites- trapped components. Rev Mineral Geochem 47 71-100 Ozima M, Kudo K (1972) Excess argon in submarine basalts and an earth-atmosphere evolution model. Nature Phys Sci 239 23-24... 

Figure 12.3 Simplified model for the various processes governing the Cu and Zn isotopic composition collected in the Talbot area of Canada [33], The ore zone is redox-active, with interactions between microbes and fluids on the sulfide ores mobilizing Cu and Zn as aqueous and gaseous complexes into the overlying sandstone and carbonate, which are about 100 m thick in total. Migration of these components occurs through micro- and macrofractures and then they are trapped in the near-surface environment on clay minerals in the till or incorporated into the biosphere, including trees, moss, and organic matter in the soils.

The fact that most metamorphic inclusions are secondary has led to the diffuse opinion that they are useless. Notwithstanding the evidence that they are an intrinsic part of the rock and have consequently to be studied, I see the problem in an entirely different way primary and secondary inclusions are exactly alike neither is "a priori" secure as any is liable to have suffered one of the many processes which may alter the representativity of the enclosed fluid, such as selective trapping, leakage, necking down or reaction with the host mineral. Therefore any fluid inclusion data must be compared with results derived independently by other methods. This is the point at which we are now, as many of these data became available in metamorphic petrology from experimentation or theoretical models. Only when some limiting conditions have been fulfilled may additional data be obtained and it comes then... 

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