An internally consistent triple oxygen isotope calibration of standards for silicates, carbonates and air relative to VSMOW2 and SLAP2
An internally consistent triple oxygen isotope calibration of standards for silicates, carbonates and air relative to VSMOW2 and SLAP2
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DOI：
10.1016/j.chemgeo.2019.119432
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发表时间：
2020-02-05
期刊：
影响因子：
3.9
通讯作者：
Sharp, Zachary D.
中科院分区：
文献类型：
--
作者：
Wostbrock, Jordan A. G.;Cano, Erick J.;Sharp, Zachary D.
高精度三氧同位素测量正在成为实验室中更常见的分析。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 的三氧同位素值，并按照 VSMOW2-SLAP2 标度进行校准。我们分析了 VSMOW2 和 SLAP2 来校准我们的参考气体。我们测得的 SLAP2 Delta O-18 值为 -55.55 ppm，与公认的 -55.5 ppm 值无法区分。我们的 SLAP2 Delta'O-17 值 (lambda = 0.528) 不是零，而是 -0.015 千分之一，对应于 -29.741 千分之 Delta O-17 值。碳酸盐标准品 NBS19、IAEA603 和 NBS18 的 Delta'O-17 值分别为 -0.102、-0.100 和 - 0.048 ppm (+/- 0.010)。对于 25°C 下磷酸消化释放的方解石 CO2，25°C 下的 theta(ACID) 值为 0.5230 +/- 0.0003。这些结果可用于校正其他实验室磷酸消化释放的二氧化碳的三氧同位素测量。我们提供 UW Garnet-2、NBS-28、圣卡洛斯橄榄石 (NM-SCO) 和我们内部石英标准品 (NM-Q) 的三氧同位素值。 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 Delta O-17 和 Delta O-18 值分别为千分之 12.178 (+/- 0.066) 和千分之 24.046 (+/- 0.117)，相应的 Delta'O-17 值为 -0.441 +/- 0.012 千分之二。有了通用标准，所有进行 delta O-17-delta O-18 测量的实验室都可以相对于 VSMOW2-SLAP2 标度校准其参考气体。实验室使用磷酸消解对碳酸盐释放的二氧化碳进行三氧同位素测量，可以校正大量碳酸盐值。
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 delta O-18 value of SLAP2 is -55.55 parts per thousand, indistinguishable from the accepted value of -55.5 parts per thousand. Our Delta'O-17 value of SLAP2 (lambda = 0.528) is not zero, but rather -0.015 parts per thousand, corresponding to a delta O-17 value of -29.741 parts per thousand. The Delta'O-17 values of carbonate standards NBS19, IAEA603 and NBS18 are -0.102, -0.100 and - 0.048 parts per thousand, respectively (+/- 0.010). For CO2 of calcite liberated by phosphoric acid digestion at 25 degrees C, the theta(ACID) value at 25 degrees 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 delta O-17 and delta O-18 values for air are 12.178 parts per thousand (+/- 0.066) and 24.046 parts per thousand (+/- 0.117), respectively, with a corresponding Delta'O-17 value of -0.441 +/- 0.012 parts per thousand. With the availability of common standards, all laboratories making delta O-17-delta O-18 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.