Geological materials, isotopes

Raptis K, Mayer K, Hendrickx F, De Bievre P (1998) Preparation and certification of new thorium isotopic reference materials. Fresenius J Anal Chem 361 400-403 Rehkamper M, Halliday AN (1999) The precise measurement of T1 isotopic compositions by MC-ICP-MS Application to the analysis of geological materials and meteorites. Geochim Cosmochim Acta 63 935-944... 

Turner S, van Calsteren P, Vigier N, Thomas L (2001) Determination of thorium and uranium isotope ratios in low concentration geological materials using a fixed multi-collector-lCP-MS. J Anal At Spectrom 16 612-615... 

Early studies of Mg isotope ratios in geological materials used the notation A Mg to mean per mil deviations from a standard as expressed in Equation (1) above, a convention that persists today (e.g., Elsu et al. 2000). The values assigned to A "Mg in those studies represent the level of mass-dependent isotopic fractionation relative to the standard. The same convention defined fi Mg as the per mil deviation from the standard after correction for the mass fractionation evidenced by A "Mg. In this system of nomenclature, A values refer to mass dependentfractionations while 5 values refer to deviations from mass-dependent fractionation (i.e., the S Mg defines excesses in Mg relative to mass fractionation attributable to decay of the extinct nuclide Al). In some cases A "Mg has been replaced by the symbol Fn,g (Kennedy et al. 1997) where the F refers to fractionation. ... 

Kumar N, Anderson RF, Mortlock RA, Froelich PN, Kubik P, Dittrich-Hannen B, Suter M (1995) Increased biological productivity and export production in the glacial southern ocean. Nature 378 675-680 Malinovsky D, Stenberg A, Rodushkin I, Andren H, Ingri J, Ohlander B, Baxter DC (2003) Performance of high resolution MC-ICP-MS for Fe isotope ratio measurements in sedimentary geologic materials. J Anal... 

The first modem observations of Mo isotope fractionations in geological materials were made using this method (Barling et al. 2001), employing Zr and Ru spikes with online correction for isobaric interferences from these spikes (Anbar et al. 2001). Precision of 0.25%o was reported in measurement of 8 Mo, with comparable results for other ratios. 

Fig. 2.9 Carbon isotope fractionations between various geologic materials and CO2 (after Chacko et al. 2001)...

Leclerc AJ, Labeyrie LC (1987) Temperature dependence of oxygen isotopic fractionation between diatom silica and water. Earth Planet Sci Lett 84 69-74 Ldcuyer C, Grandjean P, Reynard B, Albarede F, Telouk P (2002) B/ °B analysis of geological materials by ICP-MS Plasma 54 application to bron fractionation between brachiopod calcite and seawater. Chem Geol 186 45-55... 

High precision determination of Rb/ Rb isotope ratios by MC-ICP-MS (Isoprobe, Micromass) is advantageous in comparison to MC-TIMS (VG Sector 54, Micromass) due to an unproved precision, and fraction capability problems can be easily considered using admixed Zr for mass bias correction via the Zr/ °Zr isotope ratio. Rb isotopic composition in geological materials (basalt, granite and greywacke) and synthetic samples (in house mica standard, NBS 607 K-fsp standard) have been examined with a reproducibility of Rb/ Rb measurements of 0.02-0.05 % (2 O ). No anomalous isotope fractionation was observed for the samples investigated. 

Figure 7 Oxygen isotopic compositions in martian meteorites define a distinct mass fractionation line from that of terrestrial geologic materials. Open circles are mean values of Clayton and Mayeda (1996), and filled circles are mean values of Franchi et al. (1999).

---