Do thermochemical convection models explain wave propagation and scattering?

热化学对流模型可以解释波传播和散射吗？

基本信息

批准号：
1644829
负责人：
Jeroen Ritsema
金额：
$ 20.4万
依托单位：
Regents of the University of Michigan - Ann Arbor
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-01-01 至 2022-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1644829&HistoricalAwards=false
关键词：
Do thermochemical convection models explain

项目摘要

The theory of Plate Tectonics is a theory of Earth dynamics. The movements of tectonic plates cause earthquake faulting and volcanic eruptions, they result in the uplift of Earth's mountain ranges, and they explain the complexity of geologic formations around the world. However, it remain unclear how plate tectonics is tied to large-scale rock flow in Earth's interior. Near tectonic collision zones, the oceanic lithosphere descends deep into Earth's interior, in some places to the bottom of the mantle at a depth of about 1800 miles. The compositionally distinct crust is carried along with the oceanic plate. It will separate from the plate and circulate freely within the mantle. Since this process has been ongoing for billions of years, we expect that 10 to 100 mile size chunks of the crust have been dispersed throughout the mantle. Mapping the variable concentration of these fragments of the crust in the mantle will help us understand how Earth's interior is flowing. The project will support one PhD student and several undergraduate students via the Undergraduate Research Opportunities Program at U Michigan. The research expands an ongoing international collaboration that provides important international experience to the PhD student at Michigan and students in Japan, China, and the United Kingdom who are directly involved in the project.The mixing of ancient crust in the mantle depends on the density of the crust with respect to the ambient mantle and the vigor of flow in the mantle. The team's research is aimed at constraining these parameters by studying how earthquake generated seismic waves are scattered by crustal fragments in the deep mantle. They will study seismic wave scattering from an experimental and theoretical point of view. An international team of investigators will work with rock physicists to constrain the density and elastic properties of crustal fragments at the high-temperature and high-pressure conditions deep in Earth's mantle. They will map seismic wave scattering using roughly 150,000 seismograms from the Global Seismic Network and from the USArray, a network of seismographs in the United States that has been operating during the past decade. The investigators will simulate seismic wave scattering using computer simulations of mantle mixing and by computing seismic wave scattering on high-performance computers. Using this joint approach, they hope to constrain the vigor of mantle flow and to understand whether the settling of dense crustal fragments at the base of the mantle explains broad regions of compositional heterogeneity in Earth's deep interior. The research will add to understanding of our planet's evolution and how plate tectonics works.

板块构造理论是地球动力学的理论。构造板块的运动引起地震断层和火山喷发，导致地球山脉的隆起，并解释了世界各地地质构造的复杂性。然而，目前尚不清楚板块构造如何与地球内部的大规模岩石流联系起来。在构造碰撞带附近，海洋岩石圈深入地球内部，有些地方深入到地幔底部，深度约 1800 英里。成分不同的地壳随海洋板块一起移动。它将与板块分离并在地幔内自由循环。由于这个过程已经持续了数十亿年，我们预计 10 到 100 英里大小的地壳块已经分散在整个地幔中。绘制地幔中这些地壳碎片的不同浓度图将有助于我们了解地球内部是如何流动的。该项目将通过密歇根大学的本科生研究机会计划为一名博士生和几名本科生提供支持。该研究扩大了正在进行的国际合作，为密歇根大学的博士生以及直接参与该项目的日本、中国和英国的学生提供了重要的国际经验。古代地壳在地幔中的混合取决于地幔的密度地壳相对于周围地幔的关系以及地幔中流动的活力。该团队的研究旨在通过研究地震产生的地震波如何被深部地幔中的地壳碎片散射来限制这些参数。他们将从实验和理论的角度研究地震波散射。一个国际研究小组将与岩石物理学家合作，限制地幔深处高温高压条件下地壳碎片的密度和弹性特性。他们将使用来自全球地震网络和过去十年一直在运行的美国地震仪网络 USArray 的大约 150,000 个地震图来绘制地震波散射图。研究人员将使用地幔混合的计算机模拟和在高性能计算机上计算地震波散射来模拟地震波散射。利用这种联合方法，他们希望限制地幔流的活力，并了解地幔底部致密地壳碎片的沉降是否可以解释地球内部深处广泛的成分异质性区域。这项研究将增进对地球演化和板块构造如何运作的理解。