Calcite carbon Isotopes

Fig. 5. Histograms of calcite carbon isotopic compositions (A) Middle and Upper Jurassic reservoir calcite data combined (B) Middle Jurassic reservoir calcite data (C) Upper Jurassic reservoir calcite data.

Bottinga, Y. 1969 Calculated fractionation factors for carbon and hydrogen isotope exchange in the system calcite-carbon dioxide-graphite-methane-hydrogen-water vapour. Geochimica et CosmochimicaActa 33 49-64. 

Figure 1.31. Bivariable plot of oxygen versus carbon isotopic compositions of carbonates. Solid circle magnesite open circle dolomite open square calcite A oxygen and carbon isotopic compositions of igneous carbonates B oxygen and carbon isotopic compositions of marine carbonates (Shikazono et al., 1995).

Shikazono, N. (1988a) Oxygen and carbon isotopic ratios of calcite and evolution of hydrothermal activities in the Seigoshi gold-silver mining district, Japan. Mining Geology Special Issue, 12, 1-16. 

We can predict the oxygen and carbon isotopic compositions of the dolomite produced by this reaction path, using the techniques described in Chapter 19. Figure 25.4 shows the compositions of calcite and dolomite cements in the Lyons, as determined by Levandowski et al. (1973). The calcite and dolomite show broad ranges in oxygen isotopic content. The dolomite, however, spans a much narrower range in carbon isotopic composition than does the calcite. 

Romanek CS, Grossman EL, Morse JW (1992) Carbon isotopic fractionation in synthetic aragonite and calcite Effects of temperature and precipitation rate. Geochim Cosmochim Acta 56 419-430 Rowe MW, Clayton RN, Mayeda TK (1994) Oxygen isotopes in separated components of Cl and CM meteorites. Geochim Cosmochim Acta 58 5341-5347... 

Bottinga Y (1968) Calculations of fractionation factors for carbon and oxygen isotope exchange in the system calcite-carbon dioxide-water. J Phys Chem 72 800-808 Bullen TD, White AF, Childs CW, Vivit DV, Schulz MS (2001) Demonstration of significant abiotic iron isotope fractionation in nature. Geology 29 699-702... 

Chacko T, Mayeda T. K., Clayton R. N., and Goldsmith J. R. (1991). Oxygen and carbon isotope fractionations between CO2 and calcite. Geochim. Cosmochim. Acta, 55 2867-2882. 

Romanek C. S., Grossman E. L. and Morse J. W. (1989). Carbon isotope fractionation in aragonite and calcite Experimental study of temperature and kinetic effects. Geol Soc. Amer. Abstr. Prog., 2LA76. 

Carbon isotope fractionations under equilibrium conditions are important not only at low-temperature, but also at high temperatures within the system carbonate, CO2, graphite, and CH4. Of these, the calcite-graphite fractionation has become a useful geothermometer (e.g.. Valley and O Neil 1981 Scheele and Hoefs 1992 Kitchen and Valley 1995) (see discussion on p. 227). 

Scheele N, Hoefs J (1992) Carbon isotope fractionation between calcite, graphite and CO2. Contr Miner Petrol 112 35 5... 

A key question is then the relationship between the isotopic composition of the C02(g) in the soil and the CO2 dissolved in the mineral species growing in the soils. The equilibrium carbon isotope fractionations between C02(g) and carbonate minerals (CaC03 (both calcite and aragonite polymorphs), MgC03 (magnesite)) are known experimentally and can be accurately calculated from quantum chemistry (75). Overall, carbon in carbonate minerals is isotopically heavier than carbon in C02(g) by about... 

In an attempt to determine whether there might be any relationship between the carbon of the anthraxolite and that of the calcite associated with it, the ratios of stable carbon isotopes were determined for each (Table IV). The results are given as C in per mil relative to National Bureau of Standards sample NBS-22 and also relative to the Urey-Chicago Standard (PDB). 

TabU IV. Carbon Isotope Ratios for Martinsburg Anthraxolite and Calcite"... 

Fig. 3.17. Carbon isotopic enrichment factors for aragonitic (dots) and calcitic (circles) foraminifera and inorganic precipitates as a function of temperature. Shown are the inorganic precipitate data of Baertschi (1957)- circle with dot Emrich et al. (1970)- large dots and Rubinson and Clayton (1969) revised - see text aragonite - solid diamond, calcite - hollow diamond. (After Grossman, 1984.)...

Unfortunately, equations (3.19) and (3.20), although the best currently available for the data, can only be considered tentative. The weakness lies in the temperature dependence. As mentioned earlier, it is not known whether the results reflect a temperature dependence or a change in the proportion of aragonite to calcite. Another shortcoming in this relationship is that the temperature range of the experiments, 20° to 63°C (if Baertschi s data are included), is well above the temperature at which many organisms secrete carbonate. Because benthic foraminifera have proved very useful in carbon isotopic studies, it is important to have carbon isotopic equilibrium defined over their temperature range. 

O Neil J.R. and Epstein S. (1966) Oxygen isotope fractionation in the system dolomite-calcite-carbon dioxide. Science 152, 198-201. 

Hypothesis 2. Diffusion of DOC and sulfate from confining bed pore waters provides sources of electron donor (organic carbon) and electron acceptor (sulfate). Carbon dioxide produced by this reaction drives shell material dissolution/ calcite cement precipitation which can explain the major ion and carbon isotope composition of Black Creek aquifer water. 

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