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，大陆在地球表面缓慢漂移。洋壳产生于大洋中脊，并在大约一亿年后返回地球内部的俯冲带。地震学研究给我们提供了一些模糊的俯冲板块，这些板块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进行的地球化学采样，告诉我们远古板块如何被地幔吸收并通过地幔对流的缓慢搅动带回的长期故事。海洋地壳的形成和循环对地球的化学和热演化有着明显的强烈影响，但我们仍然不知道发生在地球深处的物理性质的变化如何影响地壳和热的行为。它混合回到地幔中。该研究项目将添加第三种观察动态地球的方法，即使用数学模型来预测板块构造如何影响地球的成分和热状态。这些数学模型适合预测地球在其整个时代的动态演化。然后可以将预测与当今地球的观测结果（由地震学提供）以及地球化学提供的长期视角进行比较。建模方法的新方面包括对可压缩性和主要发生的相关相变的一致处理地幔深度 440 至 670 公里之间。可压缩效应将使 PI 能够考虑热力学一致的建模，其结果可以直接与地幔当前状态的地震观测结果进行比较。研究人员将使用高分辨率的地幔对流有限元模型，其中包括模拟板块的能量一致方法。