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Chlorine isotopes contrast

Layered intrusions. Chlorine isotope studies of the Stillwater Complex of Montana, USA (e.g., Stewart et al. 1996 Boudreau et al. 1997), and the Bushveld Complex in the Republic of South Africa (e.g., Willmore et al. 2002) show that both intrusions are anomalously rich in chlorine (e.g., Boudreau et al. 1986 Willmore et al. 2000), but that, their chlorine-isotopic compositions are distinct from one another (Fig. 1). The 8 Cl values of Stillwater samples range from -0.93%o to 0.27%o with all but one value below 0.1 %o (Fig. 1). In contrast the... [Pg.237]

Seawater and marine pore fluids. As discussed above, the chlorine isotopic composition of modem seawater does not vary measurably. This is not surprising in light of its long residence hme (approximately 90 million years) and its conservative behavior in the water column. In contrast, marine pore fluids have been demonstrated to vary considerably. There is also the likelihood that hydrothermal fluids may be fractionated as a result of exchange with mineral phases, as phase separation under marine hydrothermal conditions does not appear to lead to measurable fractionation (e.g., Magenheim et al. 1995). However, to date no stable-chlorine isotopic compositions of marine hydrothermal fluids have been reported in the literature. [Pg.239]

Huang L, Sturchio NC, Abrajano T, Heraty LJ, Holt BD (1999) Carbon and chlorine isotope fractionation of chlorinated aliphatic hydrocarbons by evaporation. Org Geochem 30(8A) 777-785 Jambon A, Deruelle B, Dreibus G, Pineau F (1995) Chlorine and bromine abundance in MORB the contrasting behavior of the Mid-Atlantic Ridge and East Pacific Rise and implications for chlorine geodynamic cycle. Chem Geol 126 101-117... [Pg.251]

Volcanic gases and associated hydrothermal waters have a large range in 8 C1-values from —2 to +12%o (Bames et al. 2006). To evaluate chlorine isotope fractionations in volcanic systems, HCl liquid-vapor experiments performed by Sharp (2006) yield large isotope fractionations of dilute HCl at 100°C. These results are in contrast to liquid-vapor experiments by Liebscher et al. (2006) observing very little fractionation at 400 - 450° C. Clearly more data are needed to resolve these discrepancies. [Pg.80]

The fragmentation pathways for the methyl esters are strongly dependent on the type of acid, i.e. whether a derivative of phenoxyacetic acid, phen-oxypropionic acid, or phenoxybutyric acid, and on the nature of the substitution of the aromatic ring. The methyl esters of chlorinated phenoxyacetic and phenoxypropionic acids show reasonably abundant molecular ions (about 20% relative to the base peak) which, together with the chlorine isotope patterns, permit easy identification of these compounds. In contrast, the spectra of the methyl esters of chlorinated phenoxybutyric acids are dominated by the fragment ion at m/z 101, with only low abundance of molecular ions. However, the spectra also show... [Pg.78]

In undeuterated dioxane, Hgq and coincidentally have the same chemical shift (at the field studied), so they cannot be differentiated at low temperatures. (See Sections 1-8 and 5-2.) In l,4-dioxane- 7 (an impurity in commercial l,4-dioxane- 5 g), both and Hgq exhibit isotope shifts to a lower frequency, but H x is shifted somewhat farther. As a result, the axial and equatorial protons give separate resonances at low temperatures, in contrast to the undeuterated material. Because of a chlorine isotope effect, chloroform is a poor substance for an internal lock or a resolution standard at fields above about 9.4 T. At high resolution, the chloroform proton resonance shows up as several closely spaced peaks, due to CH( 5c1)( C1)2, CH( C1)2( C1), CH( C1)3, and CH( C1)3. [Pg.79]

Methylation of (258) with methyl iodide in dimethoxyethane gives (259) and (260) in the ratio 72 28 with methyl chloride the ratio is 81 19 which is slightly lower than the corresponding ratio obtained on methylation of (261) with methyl iodide. In contrast, methylation of (262) with either methyl chloride, methyl iodide, or methyl toluene-p-sulphonate gives (263) and (264), of which (264), the product from axial attack, constitutes 73—83%. For reactions of (258) and (262) with methyl chloride, chlorine isotope effects = 1.0063... [Pg.225]

The most recent studies of the isotopic composition of the sulfate and dissolved sulfide in the BCL conducted in 2004, however, did not confirm the existence of the lower isotopic trend in the isotopic composition of sulfide. The average sulfur isotopic composition of sulfide below 1750 m was - 40.0%o and varied between - 39.1 and - 41.5% [52], which is very similar to the isotopic composition of most of the anoxic zone (Fig. 6). In contrast, the isotope composition of sulfate in the BCL varied between + 19.9 and + 21.6% (average + 20.8%o) suggesting a slight 34S enrichment of about 1.3%o compared to the entire anoxic zone. Volkov and Rimskaya-Korsakova [52] hypothesized that the observed enrichment in sulfate sulfur was a result of the relative depletion of sulfate during bacterial sulfate reduction in this zone. These data are supported by the 2% decrease in the sulfate/chlorinity ratio observed in the BCL. [Pg.322]

What happens to chlorine at depths below those supplying fluid for subduction-related magmatism There are two contrasting views at present. Philippot et al. (1998) argue that 70% of the chlorine in the altered cmst is recycled into the mantle in order to produce an isotopic composition of chlorine equal to that in the source region for MORBs. Alternatively, Lassiter et al. (2002) argue that the consistency of the CI/K2O ratio of MORBs, Austral Island and other OIBs requires that the CI/K2O of the mantle does not vary... [Pg.1046]

Most elements have only one dominant isotope. For example, the dominant isotope of hydrogen is while (deuterium) and (tritium) represent only a small fraction of all hydrogen atoms. Similarly, the dominant isotope of carbon is while and represent only a small fraction of all carbon atoms. In contrast, chlorine has two major isotopes. One isotope of chlorine, Cl, represents 75.8% of all chlorine atoms the other isotope of chlorine, Cl, represents 24.2% of all chlorine atoms. As a result, compounds that contain a chlorine atom will give a characteristically strong (M+2) " peak. For example. [Pg.700]

The painstakingly precise kinetic investigation of solvolysis of sul-phur(vi)—chlorine bonds alluded to in the first volume of this Specialist Periodical Report has been extended to include a series of 4-substituted benzenesulphonyl chlorides. In this case values of AG, A, and AG, of AC from dAH ldT, and even of d C ldT, have been reported. An Gn2 mechanism with a trigonal-bipyramidal transition state is indicated. The variation of rates with substituents and solvent composition (in aqueous dioxan) for another series of benzenesulphonyl chlorides also indicates an 5 2 mechanism, except in the case of 2,4,6-trimethylbenzene-sulphonyl chloride, where an S l mechanism seems more likely. Kinetic solvent isotope effects, D2O vs. H20, for hydrolysis of substituted benzenesulphonyl chlorides have been determined and contrasted with those for analogous organic chloride soIvolyses. Kinetic data have also been obtained for hydrolysis of methane- and ethane-sulphonyl chlorides in methanol, ethanol, and ethanol-benzene, -carbon tetrachloride, and -2,2,4-trimethylpentane solvent mixtures. These results have been discussed in terms of the effects of solvation of initial and transition states on reactivities. ... [Pg.123]


See other pages where Chlorine isotopes contrast is mentioned: [Pg.530]    [Pg.530]    [Pg.238]    [Pg.270]    [Pg.500]    [Pg.368]    [Pg.46]    [Pg.1057]    [Pg.65]    [Pg.163]    [Pg.1057]    [Pg.164]    [Pg.539]    [Pg.582]    [Pg.1]    [Pg.91]    [Pg.42]    [Pg.433]   
See also in sourсe #XX -- [ Pg.56 ]




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