Oxygen isotopes, determination

Stuart-Williams, H.L.Q. and Schwarcz, HP. 1997 Oxygen isotopic determination of climatic variation using phosphate from beaver bone, tooth enamel, and dentine. Geochimica et Cosmochimica Acta (iV. 2539-2550. 

Figure 6.4. Percent average humidity compared with 6 0 in bone phosphate. The strong association between the two variables across the species of Australian marsupials (data from Ayliffe and Chivas 1990) and North American white-tailed deer (data from Luz ei a/. 1990) indicates that their body water oxygen isotopic composition is strongly determined by the 8"0 in their diet since plant 8 0 varies in negative correlation with humidity.

Sharp, Z.D. 1990 A laser-based microanalytical method for the in situ determination of oxygen isotope ratios of silicates and oxides. Geochimica et Cosmochimica Acta 54 1353-1357. 

Zheng, Y.F. (1996) Oxygen isotope fractionations involving apatites Application to paleotemperature determination. Chem. Geol, 127, 177-187. 

There are a number of light stable isotope measurements that provide very important data in the study of paleoclimates to better understand and interpret anthropogenic contributions to present-day climate change (Fritz and Fontes 1980). These measurements involve the determination of carbon and oxygen isotopes in fresh-... 

Olley JM, Roberts RG, Murray AS (1997) A novel method for determining residence times of river and lake sediments based on disequilibriiun in the thorium decay series. Water Resom Res 33 1319-1326 Onac BP, Lauritzen S-E (1996) The climate of the last 150,000 years recorded in speleothems preliminary results from north-western Romania. Theor Appl Karstology 9 9-21 O Neil JR., Clayton RN, Mayeda TK (1969) Oxygen isotope fractionation in divalent metal carbonates. J ChemPhys 51 5547-5558... 

Calcium carbonate is also the main constituent of the shells of sea animals, which make their shells from elements acquired from the surrounding waters. Now, the degree of fractionation of the oxygen isotopes as well as the formation of mineral carbonates and of animal shells in sea waters are determined on the basis of the temperature-dependent fractionation of the isotopes of oxygen the oxygen isotope composition of these materials reflects, therefore, the temperature at the time of their formation. Thus determining the isotope ratio between the stable isotopes of oxygen... 

Determining the temperature at which ancient sediments were formed entails two successive experimental stages (1) extracting the carbon dioxide from the sediments and (2) determining the relative amounts of the oxygen isotopes in the extracted carbon dioxide. Treating a sediment with a standard acid, such as hydrochloric or sulfuric acid, dissolves the calcium and magnesium carbonates in the sediments and... 

Shackleton, N. J. (1973), Oxygen isotope analysis as a means of determining season of occupation of prehistoric hidden sights, Archaeometry 15,133-141. 

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. 

An important criticism of the use of combustion trains is that combustion is not site specific, that is all atoms in the analyte end up in the gas transferred to the IRMS. For studies of carbon isotope effects this is invariably C02. The question is especially important for carbon isotope analysis because analyte molecules of interest usually contain several different kinds of carbon atoms and therefore combustion methods average or dilute the IE s of interest. Should site specific isotope ratios be required another method of sample preparation (usually much more tedious) is necessary. Combustion methods, however, are frequently used to study nitrogen and sulfur IE s because many organic molecules are singly substituted with these atoms. Obviously, oxygen isotope effects cannot be determined using combustion trains because external oxygen is employed. Rather some type of pyrolytic sample preparation is required. 

Fortier SM, Cole DR, Wesolowski DJ, Riciputi LR, Paterson BA, Valley JW, Horita J (1995) Determination of the magnetite-water equilibrium oxygen isotope fractionation factor at 350°C a comparison of ion microprobe and laser fluorination techniques. Geochim Cosmochim Acta 59 3871-3875 Friedman I, O Neil JR (1977) Compilation of Stable Isotope Fractionation Factors of Geochemical Interest. US Geol Surv Prof Paper 440-KK... 

Knowledge of the oxygen isotope fractionation between liquid water and water vapor is essential for the interpretation of the isotope composition of different water types. Fractionation factors experimentally determined in the temperature range from 0 to 350°C have been suntunarized by Horita and Wesolowski (1994). This is shown in Fig. 2.13. 

Table 2.6 Experimentally determined oxygen isotope fractionation factors relative to water for the aqueous system CO2 — H2O between 5 and 40°C according to 10 hia = A(10 /T ) + B (Beck et al, 2005)...

Of equal importance is the oxygen isotope fractionation in the CO2 - H2O system. Early work concentrated on the oxygen isotope partitioning between gaseous CO2 and water (Brennikmeijer et al. 1983). More recent work by Usdowski and Hoefs (1993), Beck et al. (2005) and Zeebe (2007) have determined the oxygen isotope composition of the individual carbonate species that are isotopically different at room temperature. Table 2.6 summarizes the equations for the temperature dependence between 5 and 40°C (Beck et al. 2005). 

On the basis of these systematic tendencies of emichment found in nature, significant temperature information can be obtained np to temperatures of 1,000°C, and even higher, if calibration cnrves can be worked ont for the varions mineral pairs. The pnbhshed hterature contains many calibrations of oxygen isotope geothermometers, most are determined by laboratory experiments, althongh some are based on theoretical calcnlations. 

The measured 8 C- and 8 0-values of carbonates can be used to estimate the carbon and oxygen isotope composition of the fluid in the same way as has been discussed before for oxygen and hydrogen. The isotopic composition of carbon and oxygen in any carbonate precipitated in isotopic equilibrium with a fluid depends on the isotopic composition of carbon and oxygen in the fluid, the temperature of formation, and the relative proportions of dissolved carbon species (CO2, H2CO2, HCO2, and/or ). To determine carbonate speciation, pH and temperature must... 

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