Consequences of plate tectonics in a compressible mantle

可压缩地幔中板块构造的后果

• 批准号: 1246700
• 负责人: Peter van Keken
• 金额: $ 24.99万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246700&HistoricalAwards=false
• 关键词: Consequences; plate; tectonics; compressible; mantle

Continents slowly drift across the Earth's surface due to the forces of plate tectonics. Oceanic crust is generated at mid-oceanic ridges and is returned after some one hundred million years back into the Earth's interior at subduction zones. Seismological investigations give us a blurry few of the subducting slabs that appear to sink towards the base of the mantle. Geochemical sampling at mid-oceanic ridge volcanoes and at hotspots such as Hawaii tell us the long term story about how the ancient slabs are absorbed by the mantle and brought back up by the slow churning of mantle convection. The formation and recycling of oceanic crust has a clear strong influence on the chemical and the thermal evolution of the Earth, but we remain in the dark as how changes in physical properties, that occur deeper in the Earth, affect the behavior of the crust and its mixing back into the mantle. This research project will add a third way of looking at the dynamic Earth by use mathematical models that predict how plate tectonics affects the composition and thermal state of the Earth. The mathematical models are suited to predict the dynamical evolution of the Earth over its entire age. The predictions can then be compared to the observations of the present day Earth (as provided by seismology) and the longer term perspective that geochemistry provides.The new aspects of the modeling approach include the consistent treatment of compressibility and the associated phase changes that occur primarily between 440 and 670 km depth in the Earth's mantle. The compressible effects will allow the PI to consider thermodynamically consistent modeling where the results can be compared directly to seismological observations of the present day state of the Earth's mantle. The investigators will use high resolution finite element models of mantle convection that include a energetically consistent approach to simulated plates.

由于板块构造的力量，大陆缓慢地在地球表面漂移。洋壳产生于洋中脊，大约一亿年后又回到地球内部的俯冲带。地震学的调查给了我们一些模糊的俯冲板块，它们似乎向地幔底部下沉。在大洋中脊火山和夏威夷等热点地区的地球化学采样告诉我们，古老的板块是如何被地幔吸收，并通过地幔对流的缓慢搅动而被带回来的。海洋地壳的形成和再循环对地球的化学和热演化有着明显的强烈影响，但我们仍然不知道地球深处物理性质的变化如何影响地壳的行为及其与地幔的混合。该研究项目将通过使用数学模型来预测板块构造如何影响地球的组成和热状态，从而增加观察动态地球的第三种方式。这些数学模型适用于预测地球在其整个年龄的动力学演化。预测结果可以与现今地球的观测结果（如地震学所提供的）和地球化学提供的长期前景进行比较。建模方法的新方面包括对主要发生在地幔440至670公里深处的可压缩性和相关相变的一致处理。可压缩效应将允许PI考虑物理上一致的建模，其中结果可以直接与地球地幔现今状态的地震观测进行比较。研究人员将使用高分辨率的地幔对流有限元模型，其中包括一个能量一致的方法模拟板。