A Global Study of Anisotropy and Composition in Earth's Mantle

地幔各向异性和成分的全球研究

• 批准号: 0538238
• 负责人: T. Guy Masters
• 金额: $ 38万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538238&HistoricalAwards=false
• 关键词: Global; Study; Anisotropy; Composition; Earth

A Global Study of Anisotropy and Composition in Earth's MantleThe method of choice for imaging the detailed 3D structure of the Earth is global seismic tomography. To date, the focus of global seismic tomography has been to image lateral variations in seismic velocities throughout the mantle and to infer their cause and implications for the evolution of the Earth. The main focus of this grant is to work towards an integrated model of anisotropy of the whole mantle. Anisotropy is the directional dependence of seismic wave speed caused by alignment of anisotropic crystals or the development of texture in a flow field. Thus, anisotropy is at least as important as heterogeneity from a dynamical point of view as it gives us a glimpse of flow and deformation in the deep Earth.Resolving anisotropy throughout the mantle is a complex task as anisotropy takes fundamentally different forms in different parts of the mantle. Thus, inversions that assume simple forms of anisotropy throughout the mantle are likely doomed to failure. Here, we follow a strategy that allows us to integrate many different data types to generate a model of anisotropy that can explain the bulk of the observations.Since we are also interested in developing a global view of anisotropy, we are also increasing the quantity and quality of splitting observations by adapting and applying some recent observational techniques to large databases of (several million) seismograms which include globally distributed recordings as well as regional arrays. The main goal of this work is a first truly global look at anisotropy throughout the mantle.Results of this research will be widely disseminated to the research community through a web site and anonymous ftp. This project will create detailed global images of mantle structure and anisotropy leading to an improved understanding of the history and tectonics of our planet. Finally, this grant supports graduate student education at SIO.

对地幔各向异性和成分的全球研究 对地球详细 3D 结构进行成像的首选方法是全球地震层析成像。迄今为止，全球地震层析成像的重点是对整个地幔地震速度的横向变化进行成像，并推断其原因和对地球演化的影响。这笔赠款的主要重点是致力于建立整个地幔各向异性的综合模型。各向异性是由各向异性晶体的排列或流场中纹理的发展引起的地震波速度的方向依赖性。因此，从动力学的角度来看，各向异性至少与异质性一样重要，因为它让我们了解地球深处的流动和变形。解决整个地幔的各向异性是一项复杂的任务，因为各向异性在地幔的不同部分采取根本不同的形式。因此，假设整个地幔具有简单形式的各向异性的反演可能注定会失败。在这里，我们遵循一种策略，允许我们整合许多不同的数据类型来生成可以解释大部分观测结果的各向异性模型。由于我们也有兴趣开发各向异性的全局视图，因此我们还通过将一些最新的观测技术应用于（数百万）地震图的大型数据库（包括全球分布的记录和区域阵列）来提高分裂观测的数量和质量。这项工作的主要目标是首次真正在全球范围内观察整个地幔的各向异性。这项研究的结果将通过网站和匿名 ftp 广泛传播给研究界。 该项目将创建地幔结构和各向异性的详细全球图像，从而加深对地球历史和构造的了解。最后，这笔赠款支持 SIO 的研究生教育。