EaGER: Inclusions of fluid-related minerals in diamonds from the transition zone or lower mantle

EaGER：来自过渡带或下地幔的钻石中与流体相关的矿物内含物

• 批准号: 1838330
• 负责人: Oliver Tschauner
• 金额: $ 4.04万
• 依托单位: University of Nevada Las Vegas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1838330&HistoricalAwards=false
• 关键词: EaGER; Inclusions; fluid; related; minerals

Although the surface of the Earth can be easily observed at many scales, the interior of the Earth is opaque and not accessible. There are only a small number of samples of minerals and rocks that derive from depths greater than 100 km. Natural diamonds are not only the hardest natural materials we know but also our most valuable resources for direct interrogation of greater depths in the Earth's interior. This Early Grant for Exploratory Research (EaGER) will support the study of a few precious diamond inclusions that are rich in fluid-bearing minerals, such as ice and calcite. The project will explore new methods in the study of unusual diamond inclusion, using state-of-the-art spectroscopic tools. The purpose of this EaGER is to expand on recent studies that have reported the occurrence of inclusions of ice-VII in diamonds from locations in Africa and China. Other inclusions of fluid-related crystalline precipitates such as magnesian calcite and halite have been identified and are expected to have residual pressures of 5-12 GPa and up to 25 GPa. Other inclusions of minerals of high residual pressure such as ilmenite and taenite have also been identified as inclusions that might have formed within the Transition Zone and lower mantle. This EaGER will extend the preliminary study to constrain pressure- and temperature regimes of fluid occurrences in the Transition Zone by analyzing a larger number of diamond inclusions using synchrotron micro-XRD and-XRF, optical spectroscopy, and subsequent EPMA wherever applicable. The results should contribute to to our understanding of the global water- and carbon budget by using an entirely combination of methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

虽然地球表面可以很容易地在许多尺度上观察到，但地球内部是不透明的，无法接触到。只有少量来自100公里以上深度的矿物和岩石样本。天然钻石不仅是我们所知的最坚硬的天然材料，而且也是我们直接询问地球内部更深处的最宝贵的资源。这项早期的探索性研究拨款(EIGER)将支持对几个富含流体矿物的珍贵钻石包裹体的研究，如冰和方解石。该项目将使用最先进的光谱工具，探索研究不寻常钻石包裹体的新方法。这份报告的目的是扩大最近的研究，这些研究报告了来自非洲和中国的钻石中出现了ICE-VII包裹物。已发现与流体有关的结晶沉淀物的其他包裹体，如镁方解石和岩盐，预计其残余压力为5-12 Gpa，最高可达25 Gpa。其他残留压力较高的矿物包裹体，如钛铁矿和网纹石，也被确定为可能形成于过渡带和下地幔的包裹体。通过使用同步加速器显微X射线衍射仪和X射线荧光光谱仪分析大量的钻石包裹体，光学光谱分析，以及随后的EPMA(在适用的情况下)，这将扩展初步研究，以限制过渡区流体赋存的压力和温度状态。这一结果应该有助于我们通过使用完全结合的方法来理解全球水和碳预算。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

HIMU geochemical signature originating from the transition zone

• DOI: 10.1016/j.epsl.2020.116323
• 发表时间: 2020-07-15
• 期刊: EARTH AND PLANETARY SCIENCE LETTERS
• 影响因子: 5.3
• 作者: Huang, Shichun;Tschauner, Oliver;Tischler, Jon
• 通讯作者: Tischler, Jon