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An internally consistent triple oxygen isotope calibration of standards for silicates, carbonates and air relative to VSMOW2 and SLAP2
Chemical Geology ( IF 3.6 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.chemgeo.2019.119432
Jordan A.G. Wostbrock , Erick J. Cano , Zachary D. Sharp

Abstract High precision triple oxygen isotope measurements are becoming a more common analysis in laboratories. There is a lack of calibrated standards to use for triple oxygen isotope measurements and this has led to data being presented on different scales rather than to the traditional VSMOW2-SLAP2 scale. Here we present triple oxygen isotope values of standard carbonates, CO2 liberated from carbonates, silicates and air calibrated to the VSMOW2-SLAP2 scale. We analyzed VSMOW2 and SLAP2 to calibrate our reference gas. Our measured δ18O value of SLAP2 is −55.55‰, indistinguishable from the accepted value of −55.5‰. Our Δ′17O value of SLAP2 (λ = 0.528) is not zero, but rather −0.015‰, corresponding to a δ17O value of −29.741‰. The Δ′17O values of carbonate standards NBS19, IAEA603 and NBS18 are −0.102, −0.100 and − 0.048‰, respectively (±0.010). For CO2 of calcite liberated by phosphoric acid digestion at 25 °C, the θACID value at 25 °C is 0.5230 ± 0.0003. These results can be used to correct triple oxygen isotope measurements of CO2 released by phosphoric acid digestion in other laboratories. We present triple oxygen isotope values for UW Garnet-2, NBS-28, San Carlos Olivine (NM-SCO), and our in-house quartz standard (NM-Q). Aliquots of NM-Q and NM-SCO are available from the Center for Stable Isotopes (CSI), New Mexico for interlaboratory comparison. Our δ17O and δ18O values for air are 12.178‰ (±0.066) and 24.046‰ (±0.117), respectively, with a corresponding Δ′17O value of −0.441 ± 0.012‰. With the availability of common standards, all laboratories making δ17O-δ18O measurements can calibrate their reference gas relative to the VSMOW2-SLAP2 scale. Laboratories making triple oxygen isotope measurements on CO2 released from carbonates using phosphoric acid digestion can correct to the bulk carbonate value.

中文翻译:

与 VSMOW2 和 SLAP2 相关的硅酸盐、碳酸盐和空气标准品的内部一致三氧同位素校准

摘要 高精度三氧同位素测量正成为实验室中越来越普遍的分析。缺乏用于三重氧同位素测量的校准标准,这导致数据以不同的尺度呈现,而不是传统的 VSMOW2-SLAP2 尺度。在这里,我们展示了标准碳酸盐、从碳酸盐、硅酸盐和空气中释放的 CO2 的三重氧同位素值,校准到 VSMOW2-SLAP2 标度。我们分析了 VSMOW2 和 SLAP2 以校准我们的参考气体。我们测得的 SLAP2 的 δ18O 值为 -55.55‰,与接受值 -55.5‰ 没有区别。我们 SLAP2 的 Δ'17O 值(λ = 0.528)不是零,而是 -0.015‰,对应于 -29.741‰ 的 δ17O 值。碳酸盐标准NBS19、IAEA603和NBS18的Δ'17O值分别为-0.102、-0.100和-0.048‰(±0.010)。对于 25 °C 磷酸消化释放的方解石 CO2,25 °C 下的 θACID 值为 0.5230 ± 0.0003。这些结果可用于校正其他实验室中磷酸消化释放的 CO2 的三氧同位素测量值。我们提供了 UW Garnet-2、NBS-28、San Carlos Olivine (NM-SCO) 和我们内部石英标准 (NM-Q) 的三重氧同位素值。NM-Q 和 NM-SCO 的等分试样可从新墨西哥州稳定同位素中心 (CSI) 获得,用于实验室间比较。我们的空气 δ17O 和 δ18O 值分别为 12.178‰ (±0.066) 和 24.046‰ (±0.117),相应的 Δ'17O 值为 -0.441 ± 0.012‰。有了通用标准,所有进行 δ17O-δ18O 测量的实验室都可以相对于 VSMOW2-SLAP2 标度校准其参考气体。
更新日期:2020-02-01
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