Sensitive high resolution ion microprobe – stable isotope (SHRIMP-SI) analysis of water in silicate glasses and nominally anhydrous reference minerals
Sensitive high resolution ion microprobe – stable isotope (SHRIMP-SI) analysis of water in silicate glasses and nominally anhydrous reference minerals
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DOI：
10.1039/c5ja00047e
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发表时间：
2015-07
影响因子：
3.4
通讯作者：
M. Turner;T. Ireland;J. Hermann;P. Holden;J. Padrón-navarta;E. Hauri;S. Turner
中科院分区：
文献类型：
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作者：
M. Turner;T. Ireland;J. Hermann;P. Holden;J. Padrón-navarta;E. Hauri;S. Turner
地质材料的低水位测量是了解地球从地幔到地壳水库的挥发性库存的基础。在这里，我们描述了微分析技术的发展，使用新的SHRIMP SI离子微探针来测量火山玻璃和名义上无水矿物（NAMs）中OH−（作为水的替代物）的丰度。首先在华盛顿卡内基研究所（CIW）的Cameca ims-6 f上分析样品，并根据先前的FTIR和测压分析进行校准。SHRIMP SI是一种大型离子探针，目前主要用于O和S同位素分析。这里使用的分析协议包括16 O −和16 O 1H −的多次收集，允许快速测量。SHRIMP SI的所有玻璃和NAM都集成在一条校准线上，可以在很宽的浓度范围内（50至15000 ppm H2O）校准16 O 1H −/16 O −至H2O。该校准线具有约10%的不确定性，其似乎仅受样品异质性的限制。SHRIMP分析的当前背景在20-40 ppm之间，但预计这将随着源室上的泵送的改善而改善。目前，通过任何技术对NAM样品进行水分析的限制是具有一系列标准物质，以使OH−校准到绝对H2O浓度。7 NAM样品（2橄榄石，2 orthopyroxenes和3单斜辉石），似乎是有前途的国际实验室H2O测量的潜在标准的数据。这些NAM样品已分析和表征SHRIMP SI，FTIR，EMP和Cameca ims-6 f离子微探针在CIW。这些样品中的四个先前已经通过测压法测量以确定绝对H2O浓度。
Low-level water measurements of geological materials are fundamental in understanding the volatile inventories of the Earth from the mantle to crustal reservoirs. Here we describe the development of microanalytical techniques using the new SHRIMP SI ion microprobe to measure the abundances of OH− (as a proxy for water) in volcanic glass and nominally anhydrous minerals (NAMs). Samples were first analysed at the Carnegie Institute of Washington (CIW) on their Cameca ims-6f with calibrations based on previous FTIR and manometry analyses. SHRIMP SI is a large geometry ion microprobe and is currently mainly used for O and S isotope analyses. The analytical protocol used here incorporates multiple collection of 16O− and 16O1H− allowing rapid measurements. A single calibration line incorporating all glasses and NAMs for the SHRIMP SI allows calibration of 16O1H−/16O− to H2O over a wide range in concentration (50 to 15 000 ppm H2O). This calibration line has around a 10% uncertainty, which appears to be limited only by sample heterogeneity. The current background for SHRIMP analysis is between 20–40 ppm but this is expected to improve with improved pumping on the source chamber. A current limitation to water analysis of NAM samples, by any technique, is having a range of standard materials to enable OH− calibration to absolute H2O concentrations. Data are presented for 7 NAM samples (2 olivines, 2 orthopyroxenes and 3 clinopyroxenes) that appear to be promising as potential standards for international laboratory H2O measurements. These NAM samples have been analysed and characterised here by SHRIMP SI, FTIR, EMP and the Cameca ims-6f ion microprobe at CIW. Four of these samples have previously been measured by manometry to determine absolute H2O concentrations.