New SIMS reference materials for measuring water in upper mantle minerals
New SIMS reference materials for measuring water in upper mantle minerals
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DOI：
10.2138/am-2017-5863ccbyncnd
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发表时间：
2017-03-01
影响因子：
3.1
通讯作者：
Hauri, Erik H.
中科院分区：
文献类型：
--
作者：
Kumamoto, Kathryn M.;Warren, Jessica M.;Hauri, Erik H.
上地幔中名义上无水矿物中的微量水可以显著影响其热力学和流变学性质。二次离子质谱（西姆斯）已成为定量这些矿物中少量水的主流技术，但取决于已知水浓度的标准。目前使用的地幔矿物标准是很好的特点（Hauri等人，2002年;古贺等人，2003年; Aubaud等人，2007年; Mosenfelder and Rossman 2013 a，2013 b），但由于缺乏额外的材料，限制了这项技术在其他实验室的推广。我们提出了适合用作校准参考的天然地幔捕虏体辉石的新的西姆斯测量结果材料.它们是根据华盛顿卡内基研究所地磁系目前使用的辉石标准进行校准的（古贺等人，2003年; Aubaud等人，2007年）。它们具有均匀的水含量，定义为多个谷物分析的标准偏差< 10%。水的参考材料覆盖范围从52至328 ppm和9至559 ppm的斜方辉石和单斜辉石，分别涵盖了大部分的地幔水含量的观测范围。样本均匀分布在这些范围内。根据以前的观察，这两种矿物具有相似的校准斜率，斜方辉石标准物质也可用于测量橄榄石中的水。新的辉石标准物质也可用于校准低浓度的氟和磷。我们发现，氟，特别是均匀的斜方辉石和单斜辉石，浓度为3至50 ppm的斜方辉石和0.5至118 ppm的单斜辉石。磷的范围从低于检测高达19 ppm的斜方辉石和高达73 ppm的单斜辉石，但在一些样品中更不均匀。在本研究中，大多数参考材料的氟和磷浓度都处于范围的下限，只有少数样品显示出较高的浓度。
Trace amounts of water in the nominally anhydrous minerals of the upper mantle can dramatically affect their thermodynamic and rheological properties. Secondary ion mass spectrometry (SIMS) has become a mainstream technique for quantifying small amounts of water in these minerals, but depends on standards with known concentrations of water. The current standards in use for mantle minerals are well-characterized (Hauri et al. 2002; Koga et al. 2003; Aubaud et al. 2007; Mosenfelder and Rossman 2013a, 2013b), but a lack of extra material has limited the spread of this technique to other laboratories.We present new SIMS measurements on natural mantle xenolith pyroxenes that are suitable for use as calibration reference materials. They are calibrated off of the pyroxene standards currently in use at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington (Koga et al. 2003; Aubaud et al. 2007). They have homogeneous water contents, defined as a standard deviation of < 10% for analyses across multiple grains. Reference materials for H2O cover ranges from 52 to 328 ppm and from 9 to 559 ppm in orthopyroxene and clinopyroxene, respectively, covering most of the observed range of mantle water contents. The samples are evenly distributed over those ranges. The orthopyroxene reference materials can also be used to measure water in olivine based on previous observations that these two minerals have similar calibration slopes.The new pyroxene reference materials can also be used to calibrate fluorine and phosphorus at low concentrations. We found that fluorine in particular was homogeneous in both orthopyroxene and clinopyroxene, with concentrations of 3 to 50 ppm in orthopyroxene and 0.5 to 118 ppm in clinopyroxene. Phosphorus ranges from below detection up to 19 ppm in orthopyroxene and up to 73 ppm in clinopyroxene, but was more heterogeneous within some samples. Most of the reference materials have concentrations at the lower end of the ranges for fluorine and phosphorus in this study, with only a few samples showing higher concentrations.