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.

与硅酮相比，铁粒元素是那些对金属偏爱的化学元素。对于地球而言，这些元素的丰度受到金属核的隔离的强烈影响，并且也可能受到仅在早期地球（地幔和地壳）中仅发生的过程的影响。对于这个项目，我们将进行合作的协同研究，结合了辅助元素浓度和同位素组成的观测，并进行地球动力学建模，以研究地球早期披风中化学异质性的起源和演变。这项工作的结果将是对导致地幔中铁质元素丰度的全球过程的改进理解，并为地幔的分化和混合历史提供了新的见解。一项特定的任务是检查陆地岩石中182W同位素异常的岩石学和年代学范围。作为短暂的182小时（T½= 900万年）的衰减产物，182W的变化可能反映了地球历史的前3000万年内发生的过程。我们已经确定了同位素异常的古老岩石，例如，将检查现代岩石，例如中海山脊，海洋橄榄岩和海洋岛玄武岩等现代岩石。与这项工作相辅相成，我们将建模大规模过程，例如岩浆海洋结晶，并具有产生以产生观察到的同位素方差所需的元素丰度和分馏为特征的地幔结构域。该项目将涉及马里兰州大学（UMD）的本科参与者的认真贡献。因此，这里提出的一些研究将有助于灌输同位素地球化学和地球动力学建模的方法以及结果的呈现的方法。该项目还将涉及两个机构的博士后。该提案的协作性质，以及UMD和卡内基科学机构的紧密近端，将允许经常进行直接互动，涉及对PI？S和Doestocs在该项目上工作的结果和后果的地球力学建模。