Augustin, Nico

Böhm, Florian

Eisenhauer, Anton

Fietzke, Jan

Krabbenhöft, André

Liebetrau, Volker

Peucker-Ehrenbrink, B.

Vollstaedt, Hauke

English

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Geophysical Research Abstracts,Vol. 11, EGU2009-12334-1, 2009EGU General Assembly 2009© Author(s) 2009Strontium Isotope Fractionation in the marine Realm: first application ofa 87Sr/84Sr-Double SpikeA. Eisenhauer (1), A. Krabbenhöft (1), F. Böhm (1), V. Liebetrau (1), J. Fietzke (1), N. Augustin (1), B.Peucker-Ehrenbrink (2), and H. Vollstaedt (1)(1) IFM-GEOMAR, Kiel, Germany (aeisenhauer@ifm-geomar.de), (2) Woods Hole Oceanographic Institution, Woods Hole,MA, USAIn order to precisely determine 88Sr/86Sr- and 87Sr/86Sr-isotope variations in natural samples using TIMS-technique we developed a mixed 87Sr/84Sr-double spike from two solutions enriched in 84Sr and 87Sr, respectively.After mixing the two solutions the Sr-spike ratios have precisely been determined by calibration to the NBS 987standard. For the determination of natural 88Sr/86Sr- and 87Sr/86Sr-isotope variations in carbonates and silicatestwo TIMS measurements are required: an unspiked and a spiked run where the Sr-isotope ratios are arbitrarilynormalized to a fixed Sr isotope ratio (e.g. mean of the first block). For denormalization and data reduction weadopted the algorithm for Ca isotope measurements (1) presented earlier by Heuser et al.(2003) modified for Sr-isotope measurements. It was found that best results can be achieved if the 84Srspike/84Srsample ratio is higherthan about 12. The algorithm allows the simultaneous calculation of 87Sr/86Sr and 88Sr/86Sr ratios. Standard mea-surements showed a δ88/86Sr-value (δ88/86Sr=((88Sr/86Sr)Sample/(88Sr/86Sr)SRM987)-1)*1000) of 0.39 for theIAPSO seawater standard corresponding to an external reproducibility of ±0.012 (n=19). The IAPSO δ88/86Sr-value corresponds to a 87Sr/86Sr-ratio of 0.709317(9). Both values are in accordance with earlier publications (2)and theoretical predictions based on the δ88/86Sr ratio of seawater and assuming mass-dependent isotope fraction-ation. This technique allows us to correct the 88Sr/86Sr- and 87Sr/86Sr-isotope-ratios for mass dependent fractiona-tion during both column chemistry and TIMS measurement procedure. Furthermore a direct comparison of doublespike TIMS, bracketing standard and laser-ablation MC-ICP-MS (3) results are in agreement and can be used todiscuss limitation and perspectives of future Sr isotope measurements.References: 1 Heuser A., Eisenhauer A., Gussone N., Bock B., Hansen B.T. and Nägler Th.F. (2003) Measurementof Calcium Isotopes (δ44Ca) Using a Multicollector TIMS Technique. International Journal of Mass Spectrometry220, 385-397.2 Fietzke J. and Eisenhauer A. (2006) Determination of temperature-dependent stable strontium isotope(88Sr/86Sr) fractionation via bracketing standard MC-ICP-MS. Geochemistry, Geophysics, Geosystems 7,doi:10.1029/2006GC001243 (2006).3. J. Fietzke, V. Liebetrau, D. Günther, K. Gürs, K. Hametner, K. Zumholz, T. H. Hansteena and A. Eisenhauer(2008) An alternative data acquisition and evaluation strategy for improved isotope ratio precision using LA-MC-ICP-MS applied to stable and radiogenic strontium isotopes in carbonates. Journal of Analytical Atomic Spec-trometry (JAAS)

Strontium isotope fractionation in the marine realm: first application for a <sup>87</sup>Sr/<sup>84</sup>Sr-double-spike

Strontium isotope fractionation in the marine realm: first application for a <sup>87</sup>Sr/<sup>84</sup>Sr-double-spike

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