CSEDI Collaborative Research: Application of siderophile elements to mantle geodynamics

CSEDI合作研究：亲铁元素在地幔地球动力学中的应用

• 批准号: 1160728
• 负责人: Richard Walker
• 金额: $ 16.46万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-15 至 2014-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1160728&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; Application; siderophile

We propose to conduct collaborative, synergistic research combining observations of siderophile element compositions with geodynamic modeling to study the evolution of elemental and isotopic heterogeneities in the mantle. Siderophile elements are those with a preference to enter metal rather than silicates, and are thus, elements that are largely concentrated in planetary cores. The objectives of this study will be to develop a better understanding of the global processes that led to the establishment of siderophile element abundances in the mantle, assess the extent of and possible mechanisms for the long-term preservation of the siderophile elemental and isotopic heterogeneities observed in the terrestrial rock record, and combine this information with geodynamic modeling to provide new insights to develop a better understanding of the formation and early chemical evolution of the Earth. In part, this project will be accomplished via study of the petrologic and chronologic extents of 182W isotopic anomalies in terrestrial systems using a newly-developed, high precision mass spectrometry technique. Ancient rocks, such as komatiites for which we have already identified isotopic anomalies, as well as modern rocks, such as MORB, oceanic peridotites, and ocean island basalts, will be examined as part of this task. Where necessary, complementary concentration and isotopic data for other elements, such as Os and Nd, will be generated. To better understand the causes and implications of the isotopic systematics revealed, we will test, via different geodynamic models, mechanisms for the formation and dispersal of the geochemical reservoirs with the appropriate characteristics. By tracking hafnium and tungsten in models of a range of possible early Earth states, then comparing model results with observations, we will be able to rule out some early Earth formation models and also better understand mantle mixing over the evolution of the Earth.

我们建议进行合作，协同研究相结合的亲铁元素组成的地球动力学模拟的观察，研究地幔中的元素和同位素的不均匀性的演变。亲铁元素是那些倾向于进入金属而不是硅酸盐的元素，因此是主要集中在行星核心的元素。这项研究的目的是更好地了解导致地幔中亲铁元素丰度确定的全球过程，评估在陆地岩石记录中观察到的亲铁元素和同位素不均匀性长期保存的程度和可能机制，并将这些信息与地球动力学建模相结合，以提供新的见解，从而更好地了解地球的形成和早期化学演化。部分地，该项目将通过使用新开发的高精度质谱技术研究陆地系统中182 W同位素异常的岩石学和年代学范围来完成。作为这项任务的一部分，将对古代岩石，如我们已经确定同位素异常的科马提岩，以及现代岩石，如MORB，大洋橄榄岩和洋岛玄武岩进行检查。必要时，还将生成其他元素（如Os和Nd）的补充浓度和同位素数据。为了更好地理解所揭示的同位素系统学的原因和含义，我们将通过不同的地球动力学模型来测试具有适当特征的地球化学储层的形成和分散机制。通过在一系列可能的早期地球状态的模型中跟踪铪和钨，然后将模型结果与观测结果进行比较，我们将能够排除一些早期地球形成模型，并更好地了解地球演化过程中的地幔混合。