The oxygen isotope composition of San Carlos olivine on the VSMOW2-SLAP2 scale.
The oxygen isotope composition of San Carlos olivine on the VSMOW2-SLAP2 scale.
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DOI：
10.1002/rcm.7582
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发表时间：
2016-07
期刊：
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通讯作者：
A. Pack;R. Tanaka;Markus Hering;Sukanya Sengupta;S. Peters;E. Nakamura
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作者：
A. Pack;R. Tanaka;Markus Hering;Sukanya Sengupta;S. Peters;E. Nakamura
地球物质中δ 17 O值的精确测定对于理解导致氧同位素比变化的质量相关分馏过程变得越来越重要。圣卡洛斯橄榄石被广泛用作地球和外星物质氧同位素测量的参考物质。我们报告了新的圣卡洛斯橄榄石的δ 17 O值，这些值是在两个不同的实验室（哥廷根大学地球科学中心[GZG]和冈山大学Misasa地球内部研究所[ISEI]）中独立测定的，并与VSMOW 2和SLAP 2水标准进行了直接比较。方法以标准气体为对照，测定VSMOW 2、SLAP 2、GISP和San卡洛斯橄榄石的δ 17 O和δ 18 O值。在这两个实验室中，水和圣卡洛斯橄榄石样品制备的BrF 5溴。在这两个实验室中，从水和橄榄石样品中释放的O2通过相同的净化系统，并使用相同的质谱仪相对于相同的参考气体进行测量。结果两个实验室的δ 17 OVSMOW 2和δ 18 OVSMOW 2量表相对于VSMOW 2和SLAP 2的推荐组成略有压缩。来自GZG的圣卡洛斯橄榄石的新的δ '17 O 0.528值（根据VSMOW 2-SLAP 2比例δ值计算）为−36 ± 9 ppm，来自ISEI的值为−40 ± 7 ppm（1σ标准差）。这些值比相同实验室先前报告的值高约50 ppm。观察到的差异的可能原因进行了讨论。结论本研究的结果与来自相同实验室的先前数据的比较表明，为了高精度地测定δ 17 O值：（i）相对于从基本标准释放的O2校准参考气体（VSMOW 2，SLAP 2）在同一实验室是强烈建议，质谱仪的非线性不仅会影响δ ~（17）O和δ ~（18）O值，而且会影响δ ~（17）O值。然而，在δ 18 O值相似的情况下，δ 17 O的微小差异不会受到质谱仪非线性的影响。版权所有© 2016约翰威利父子有限公司.
Rationale The precise determination of Δ'17O values in terrestrial material is becoming increasingly important to understand the mass-dependent fractionation processes that cause variations in oxygen isotope ratios. San Carlos olivine is widely used as the reference material for oxygen isotope measurements of terrestrial and extraterrestrial materials. We report new Δ'17O values for San Carlos olivine that were independently determined in two different laboratories (Geoscience Center [GZG], University of Gottingen) and Institute for Study of the Earth's Interior [ISEI], Okayama University, Misasa) in direct comparison with VSMOW2 and SLAP2 water standards. Methods The δ17O and δ18O values of VSMOW2, SLAP2, GISP, and San Carlos olivine were determined relative to reference gas. In both laboratories, water and San Carlos olivine samples were prepared by BrF5 fluorination. In both laboratories, the O2 released from water and olivine samples was passed through the same purification system and measured using the same mass spectrometer relative to the same reference gas. Results In both laboratories, the δ17OVSMOW2 and δ18OVSMOW2 scales were slightly compressed with respect to the recommended composition of VSMOW2 and SLAP2. The new Δ'17O0.528 value (calculated from the VSMOW2-SLAP2 scaled δ values) of San Carlos olivine from GZG was −36 ± 9 ppm and, from ISEI, a value of −40 ± 7 ppm (1σ standard deviation) was determined. These values are ~50 ppm higher than previously reported from the same laboratories. Possible causes for the observed discrepancies are discussed. Conclusions The results of this study in comparison with previous data from the same laboratories demonstrated that for high accuracy determination of Δ'17O values: (i) calibration of the reference gas relative to O2 released from primary standards (VSMOW2, SLAP2) in the same laboratory is highly recommended, (ii) non-linearity of the mass spectrometer may not only affect δ17O and δ18O values but also Δ'17O values, and (iii) the VSMOW2-SLAP2 scaling should also be applied to analyses of rocks and minerals. Studies that are concerned with small differences in Δ'17O at similar δ18O values, however, are not affected by non-linearity of the mass spectrometer. Copyright © 2016 John Wiley & Sons, Ltd.