Simultaneous Determination of Mass-dependent Isotopic Fractionation and Radiogenic Isotope Variation of Strontium in Geochemical Samples by Multiple Collector-ICP-Mass Spectrometry
Simultaneous Determination of Mass-dependent Isotopic Fractionation and Radiogenic Isotope Variation of Strontium in Geochemical Samples by Multiple Collector-ICP-Mass Spectrometry
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DOI：
10.2116/analsci.23.1275
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发表时间：
2007-11
影响因子：
1.6
通讯作者：
T. Ohno;T. Hirata
中科院分区：
文献类型：
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作者：
T. Ohno;T. Hirata
本文提出了一种同时测定^88 Sr/^86 Sr和^87 Sr/^86 Sr的方法。前一种变化反映了物理化学过程中质量相关的同位素分馏，后一种变化则来源于母核^87 Rb的β ^-衰变以及质量相关的同位素分馏。为了确定与质量相关的同位素分馏，用Zr的指数律对^88 Sr/^86 Sr的质量区分效应进行了外部校正。对于^87 Sr/^86 Sr的放射成因生长，通过使用^88 Sr/^86 Sr比值的常规校正技术校正了^87 Sr/^86 Sr的质量相关同位素分馏效应。高纯Sr化学试剂的^88Sr/^86Sr和^87Sr/^86Sr测量的重现性分别为0.06‰（2SD，n = 20）和0.07‰（2SD，n = 20）。采用6种地球化学标准物质（火成岩：JB-1a和JA-2;碳酸盐矿物：JLs-1、JDo-1、JCp-1和JCt-1）和1个海水样品，测定了锶同位素比值（^88Sr/^86Sr和^87Sr/^86Sr）。在分析不确定性范围内，本文得到的^87 Sr/^86 Sr比值与先前发表的数据一致。火成岩样品中的^88Sr/^86Sr比值在样品内部没有显著变化，而碳酸盐样品中较轻的Sr同位素比海水样品中的富集。地球化学样品的^88Sr/^86Sr比值可以反映样品形成的物理化学过程。此外，结合样品的^88Sr/^86Sr和^87Sr/^86Sr的讨论将提供地球化学过程的多维信息。
We present a method to determine ^88Sr/^86Sr and ^87Sr/^86Sr simultaneously. The former variation reflects the mass-dependent isotopic fractionation through the physico-chemical processes, and the latter originates from β ^–-decay of the parent nuclide ^87Rb as well as the mass-dependent isotopic fractionation. In order to determine the mass-dependent isotopic fractionation, the mass-discrimination effect on ^88Sr/^86Sr was externally corrected by an exponential law using Zr. For the radiogenic growth of ^87Sr/^86Sr, the mass-dependent isotopic fractionation effect on ^87Sr/^86Sr was corrected by a conventional correction technique using the ^88Sr/^86Sr ratio. The reproducibility of the ^88Sr/^86Sr and ^87Sr/^86Sr measurements for a high-purity Sr chemical reagent was 0.06‰ (2SD, n = 20) and 0.07‰ (2SD, n = 20), respectively. Strontium isotopic ratios (^88Sr/^86Sr and ^87Sr/^86Sr) were measured on six geochemical reference materials (igneous rock: JB-1a and JA-2; carbonate mineral: JLs-1, JDo-1, JCp-1 and JCt-1) and one seawater sample. The resulting ^87Sr/^86Sr ratios obtained here were consistent with previously published data within the analytical uncertainties. The resulting ^88Sr/^86Sr ratios for igneous rock samples did not vary significantly within the samples, whereas the carbonate samples showed enrichments of the lighter Sr isotopes over the seawater sample. The ^88Sr/^86Sr ratio of geochemical samples could reflect the physico-chemical processes for the sample formation. Also, a combined discussion of ^88Sr/^86Sr and ^87Sr/^86Sr of samples will render multi-dimensional information on geochemical processes.