Oxygen isotopes carbon isotope plots

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).

Figure 7 The Vostok ice-core record (Petit et aL, 1999). (a)-(c) Carbon dioxide, methane, and oxygen isotope ratios (expressed as 5 0) of oxygen in air extracted from the ice. (d) Hydrogen isotope ratios (expressed as or 5D) in the ice. This record is a proxy for local temperature, (e) Sodium in the ice, a measure of sea salt aerosol deposition, (f) Dust in the ice, a measure of continental aerosol deposition, (a)-(c) are plotted against the estimated age of the iee air (d)-(f) are plotted against the estimated age of the ice.

Fig. 14. Plot of carbon and oxygen isotope values versus stratigraphic 35Q position. 5 C values exhibit...

They represent an isolated cluster of data points on a 6 0 vs. 6 C plot and reveal slightly heavier carbon and lighter oxygen isotopic compositions than the other marine calcites. 

Fig. 11. Plot of oxygen and carbon stable isotopic compositions of bulk carbonate samples. Note the small range in isotopic compositions of calcite in lenses despite variable ratios between early and late calcite cement. This points to similar physical and chemical conditions during replacement of early diagenetic CaC03 cement by low-Mg calcite and late calcite cement precipitation.

Table 4. Bulk-rock carbon and oxygen isotope results for dolomite cement in the Angel Formation, Angel Field. Precipitation temperatures for dolomite cement were calculated using the fractionation factor of Northrop Clayton (1966) and assuming a marine composition for the original 8 0 pore water (6 0 = 0%o). When integrating the calculated dolomite precipitation temperatures (93-97 °C) with the geohistory plot for Angel-2 (Fig. 4) an Eocene to Late Miocene age for the dolomite cement is suggested, closely matching the seismic evidence (Fig. 22c)...

Fig. 15. Cross-plot of carbon and oxygen isotope values for the Tirrawarra Sandstone siderites. The bulk-rock isotope signatures are the cumulative product of the varying proportions of the different siderite cement generations (SI, S2, S3). The pure end-member compositions of the different siderite cement generations can be estimated from samples which are dominated by a single cement generation (circled areas). Only the end-member isotope compositions of the different cement generations should be taken into consideration when evaluating multigeneration siderite cements.

Figure 17. Plot of experimentally determined oxygen isotope fractionation factors between various metal carbonates and water at low temperatures. The carbonates were synAesized by precipitation from solution or replacement of calcite. Data sources CaCOs (calcite), SrCOs, and BaCOs - O Neil et al. (1969), corrected in Friedman and O Neil...

A reliable authenticity assessment is concluded from the simultaneous consideration of multielement IRMS and enantioselective analysis. The differences of the stable isotope ratios of linalool and linalyl acetate are depicted as a three-dimensional plot of A values (d values of linalool minus d values of linalyl acetate for oxygen, hydrogen and carbon) (Fig. 17.15). This plot shows that the commercial samples S1-S5 are different from all the other samples investigated. Linalool and linalyl acetate of S1-S5 definitely are not genuine lavender oil compounds. 

Fig. 17.31 The history of temperature fluctuations based on the isotope composition of oxygen and hydrogen in the ice core drilled by the European Project for Ice Coring in Antarctica (EPICA) at Concordia Station on Dome C (75°06 S, 123°21 SE) is closely correlated with the concentrations of carbon dioxide in the ice, both of which can be indexed to the marine isotope stages in Fig. 17.30. The correlation of these parameters confirms the scope of the chmate fluctuations which include nine cold spells that terminated abruptly during the Pleistocene Epoch (i.e., Tj-Tjj, etc.). The temperature profile (black curve) is based on measurements of 6D and was plotted on the EDC3...

The use of isotope ratio mass spectrometry (IRMS) to compare the ratios of light atom isotopes in samples of forensic interest is finding increased importance. A recent report by Benson et al. details the use of IRMS to differentiate between samples of TATP that were prepared under differing conditions and from different precursors [61]. A three-dimensional plot of the carbon, hydrogen, and oxygen data clearly showed four clusters corresponding to the different sample sets. 

From the limited data at present available, there appear to be interesting differences between proton transfer involving carbon acids and oxygen acids in aprotic solvents, but more systems must be studied before definite conclusions can be drawn. In particular, an attempt should be made to correlate the extent of proton transfer in the transition state (by means of a Bronsted-type plot) with the primary isotope effect, as has been done for aqueous media. 

State [46,125,126], This has been suggested as an explanation for the observation of extended linear Bronsted plots [46,126], and it would be of interest to know if it could also lead to constant primary isotope effects. Most examples studied pertain to elimination or addition at a carbonyl group [46, 126] where proton transfer occurs between oxygen atoms. However, Kemp and Casey [75] have measured both Bronsted coefficients and isotope effects for eliminations of substituted benzisoxazoles, in which proton transfer occurs from carbon. In this case it was found that Bronsted exponents were substantially insensitive to substituents in either the base or the substrate, and for... 

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