Solving real-world analytical challenges: Developing SIMS reference materials for quantifying hydrogen contents of orthopyroxene

解决现实世界的分析挑战：开发用于量化斜方辉石氢含量的 SIMS 参考材料

基本信息

批准号：
281238608
负责人：
Professorin Dr. Esther Schmädicke
金额：
--
依托单位：
Lehrstuhl für Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/281238608?language=en
关键词：
Solving real world analytical challenges

项目摘要

Hydrogen, colloquially water, is a significant trace substance that is incorporated as hydroxyl groups in the crystal structure of so-called nominally anhydrous minerals. The presence of water in Earth mantle minerals such as pyroxene and olivine has a disproportionally large effect on the physical properties of the Earth mantle. A complete understanding of mantle rheology is therefore based upon a detailed knowledge of the content and distribution of water within the mantle. Quantitative data from all possible mantle environments are therefore needed but such data are almost exclusively confined to samples recovered from the sub-continental mantle. Only a very modest data set, produced by this proposal's principal investigator and her co-workers, exists for sub-oceanic peridotites. This obvious sampling bias can be directly attributed to sample quality: Sub-continental xenoliths generally yield high-quality material, whereas sub-oceanic and alpine-type mantle rocks are often highly complex in nature. The Erlangen group has successfully obtained the first water data for oceanic peridotites using infrared (IR) spectroscopy (being the standard method), however this dataset is confined to a relatively small number of samples. The majority of such samples show poor crystal quality due to intense fracturing and alteration, effectively prohibiting quantitative measurements via IR spectroscopy. The project proposed here is intended to overcome the limitations inherent to the IR method by developing secondary ion mass spectrometry (SIMS) as an alternative approach for quantifying water contents in complex, fine grained materials. Our intended focus is on orthopyroxene, which in the past has proven to be an ideal proxy for bulk mantle water. The key challenge we will need to overcome it that SIMS requires that a matrix-matched reference material be available for calibration. Hence, the main task of the proposed study is to identify natural orthopyroxenes that are well-suited calibrants for hydrogen quantification by SIMS. Once identified and characterized, the resulting suite of reference materials will be used for proof-of-principle SIMS measurements that will be undertaken on orthopyroxene recovered from oceanic and alpine-type mantle specimens.

氢，俗气的水是一种重要的痕量物质，在名义上无水矿物的所谓晶体结构中被掺入羟基。地幔矿物质（如辉石和橄榄石）的存在对地球地幔的物理特性的影响不成比例。因此，对地幔流变性的完全理解是基于对地幔中水的含量和分布的详细了解。因此，需要来自所有可能地幔环境的定量数据，但是此类数据几乎仅限于从次大陆地幔中回收的样品。该提案的主要研究人员及其同事仅生产出一个非常适度的数据集，存在于亚偏爱橄榄岩。这种明显的采样偏置可以直接归因于样品质量：亚盛大的异种石通常会产生高质量的材料，而次海洋和高山型地幔岩石通常在本质上是高度复杂的。 Erlangen组已使用红外（IR）光谱（作为标准方法）成功获得了海洋橄榄岩的第一个水数据，但是该数据集仅限于相对较少的样品。大多数此类样品由于严重的破裂和改变而表现出较差的晶体质量，从而有效地禁止通过红外光谱测量定量测量。此处提出的项目旨在通过开发二级离子质谱法（SIMS）来克服IR方法固有的局限性，以此作为量化复杂，细粒料材料中水含量的替代方法。我们预期的重点是邻苯二甲烯，过去事实证明，这是散装地幔水的理想代理。我们将需要克服的关键挑战，即SIMS要求使用矩阵匹配的参考材料进行校准。因此，拟议的研究的主要任务是鉴定自然邻苯二烯是SIMS氢定量的合适校准剂。一旦确定和表征，所得的参考材料套件将用于原理证明SIMS测量结果，这些测量将对从海洋和高山型地幔标本中回收的正pypyroxene进行。