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Anomalous seismic and rheological behavior of the asthenosphere beneath oceanic and continental plates.

机译：海洋和大陆板块下软流圈的异常地震和流变行为。

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摘要

The discovery of plate tectonics brought with it many questions regarding the very nature of a plate, how and why a rigid outer planetary shell is broken up, and what physical properties of the underlying mantle allow mobility of these rigid bodies. In addition early fluid dynamic models of mantle convection in the Earth's interior had to be reconciled with the idea of tectonics at the Earth's surface. In this doctoral thesis, I explore the seismic properties of the lithosphere and asthenosphere in continental and oceanic settings using inversion methods for Rayleigh waves and SKS phases. I improve previous inversion methods by considering the frequency-dependence of the incoming wavefield, testing for lateral resolution of velocity through checkerboard tests, measuring attenuation of Rayleigh waves, and considering the contribution from smaller 4theta terms in theoretical approximations for azimuthal anisotropy. I compare shear wave splitting in region S and teleseismic SKS phases for the first time in a continental setting in the western Himalayan syntaxis indicating strong sublithospheric mantle flow beneath the intensely compressional India-Asia collision zone. I also present fluid dynamic experiments of Saffman-Taylor instabilities and propose a new geodynamic model for asthenospheric flow in the oceanic mantle relating mantle converting plumes to surface plate tectonics. All of the studies presented here emphasize the importance of asthenospheric flow but is often only established after careful resolution of the lithospheric mantle. These studies show that there is significant and often complex interaction between whole mantle convection and surface plate tectonics warranting continued investigation into both continental and oceanic mantle dynamics.
机译：板块构造学的发现带来了许多有关板块本质，如何以及为何破坏刚性行星外层以及底层地幔的物理特性如何允许这些刚体活动的问题。另外，地球内部地幔对流的早期流体动力学模型必须与地球表面的构造学思想相吻合。在本博士论文中，我使用瑞利波和SKS相的反演方法探索了大陆和海洋环境中岩石圈和软流圈的地震特性。我通过考虑入射波场的频率依赖性，通过棋盘格测试来测试速度的横向分辨率，测量瑞利波的衰减以及在方位角各向异性的理论近似中考虑较小的4θ项的贡献，来改进以前的反演方法。我在喜马拉雅山西部语法的大陆性环境中首次比较了S区和远震SKS相的剪切波分裂，表明强烈压缩的印度-亚洲碰撞带下方有强烈的岩石圈以下地幔流。我还介绍了萨夫曼-泰勒不稳定性的流体动力学实验，并提出了一个新的地球动力学模型，用于将地幔转换成柱状构造为地壳构造的海洋地幔中的软流圈流动。这里提出的所有研究都强调了软流圈流动的重要性，但通常只有在仔细解决岩石圈地幔之后才能确定。这些研究表明，整个地幔对流与表层构造之间存在着显着且通常是复杂的相互作用，因此有必要继续研究大陆和海洋地幔动力学。

著录项

  • 作者

    Weeraratne, Dayanthie Sakunthala.;

  • 作者单位

    Brown University.;

  • 授予单位 Brown University.;
  • 学科 Geophysics.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 238 p.
  • 总页数 238
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地球物理学;
  • 关键词

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