CSEDI Collaborative Research: Application of Siderophile Elements to Early Earth Processes and Mantle Mixing

CSEDI合作研究：亲铁元素在早期地球过程和地幔混合中的应用

• 批准号: 1265169
• 负责人: Richard Walker
• 金额: $ 37.02万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1265169&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; Application; Siderophile

Siderophile elements are those chemical elements with a strong preference for metal compared to silicates. For the Earth, the abundances of these elements were strongly affected by segregation of the metallic core, and also likely affected by processes that occurred exclusively in the silicate portion of the early Earth (mantle and crust). For this project, we will conduct collaborative, synergistic research combining observations of siderophile element concentrations and isotopic compositions, with geodynamic modeling to study the origin and evolution of chemical heterogeneities in Earth's early mantle. The outcome of this work will be an improved understanding of the global processes that led to the establishment of siderophile element abundances in the mantle, as well as provide new insights to the differentiation and mixing histories of the mantle. One specific task will be to examine the petrologic and chronologic extents of 182W isotopic anomalies in terrestrial rocks. As the decay product of the short-lived 182Hf (t½ = 9 million years), variations in 182W likely reflect processes that occurred within the mantle during the first 30 million years of Earth history. Both ancient rocks, such as komatiites for which we have already identified isotopic anomalies, and modern rocks, such as mid-ocean ridge basalts, oceanic peridotites, and ocean island basalts will be examined. Complementary to this work, we will model large-scale processes, such as magma ocean crystallization, with the potential to generate mantle domains characterized by the elemental abundances and fractionations necessary to produce the observed isotopic variances. This project will involve serious contributions from undergraduate participants at the University of Maryland (UMd). As such, some of the research proposed here will help to indoctrinate budding scientists in the methods used in isotopic geochemistry and geodynamic modeling, as well as the presentation of results. The project will also involve postdocs at both institutions. The collaborative nature of the proposal, as well as the close proximity of the UMd and Carnegie Institution for Science, will allow frequent, direct interactions involving both geochemical data acquisition and geodynamic modeling of the results for the PI?s and postdocs working on this project.

亲铁元素是那些与硅酸盐相比对金属具有强烈偏好的化学元素。对于地球来说，这些元素的丰度受到金属核分离的强烈影响，也可能受到早期地球硅酸盐部分（地幔和地壳）专门发生的过程的影响。在这个项目中，我们将进行合作，协同研究结合亲铁元素浓度和同位素组成的观测，与地球动力学建模，研究地球早期地幔化学不均匀性的起源和演化。这项工作的成果将是一个更好的理解全球过程，导致建立亲铁元素丰度在地幔中，以及提供新的见解地幔的分化和混合的历史。一个具体的任务将是检查的岩石学和年代学范围的182 W同位素异常在陆地岩石。作为短命的182 Hf（t1/2 = 900万年）的衰变产物，182 W的变化可能反映了地球历史前3000万年地幔内发生的过程。既有古老的岩石，如我们已经发现同位素异常的科马提岩，也有现代的岩石，如洋中脊玄武岩、大洋橄榄岩和洋岛玄武岩。作为对这项工作的补充，我们将模拟大规模的过程，如岩浆海洋结晶，有可能产生地幔域的特征是元素丰度和分馏所必需的，以产生所观察到的同位素差异。这个项目将涉及严重的贡献，从本科参与者在马里兰州大学（UMD）。因此，这里提出的一些研究将有助于向新兴科学家灌输同位素地球化学和地球动力学建模所用的方法，以及结果的呈现。该项目还将涉及这两个机构的博士后。该提案的合作性质，以及UMD和卡内基科学研究所的密切联系，将允许频繁，直接的互动，涉及地球化学数据采集和地球动力学建模的结果为PI？和博士后在这个项目上工作。