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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >New evidence for dislocation creep from 3-D geodynamic modeling of the Pacific upper mantle structure
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New evidence for dislocation creep from 3-D geodynamic modeling of the Pacific upper mantle structure

机译：太平洋上地幔结构的3-D地质动力学模型为位错蠕变提供了新的证据

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摘要

Laboratory studies on deformation of olivine in response to applied stress suggest two distinct deformation mechanisms in the earth's upper mantle: diffusion creep through diffusion of atoms along grain boundaries and dislocation creep by slipping along crystallographic glide planes. Each mechanism has very different and important consequences on the dynamical evolution of the mantle and the development of mantle fabric. Due to the lack of in situ observations, it is unclear which deformation mechanism dominates in the upper mantle, although observed seismic anisotropy in the upper mantle suggests the presence of dislocation creep. We examined the thermo-mechanical erosion of the lithosphere by thermal boundary layer instabilities in 3-D dynamical models. This study demonstrates that the seismically derived thermal structure of the Pacific lithosphere and upper mantle imposes an important constraint on the upper mantle deformation mechanism. The predominant deformation mechanism in the upper mantle is dislocation creep, consistent with observed seismic anisotropy. The acceptable activation energy range of 360-540 kJ/mol is consistent with, although at the lower end of, those determined from laboratory studies. (c) 2005 Elsevier B.V. All rights reserved.
机译：橄榄石在外加应力作用下的变形的实验室研究表明，地球上地幔有两种不同的变形机制：通过原子沿晶界扩散的扩散蠕变和通过沿晶体滑移面滑动的位错蠕变。每种机制对地幔的动力学演化和​​地幔构造的发展都具有非常不同和重要的影响。由于缺乏原位观测，尚不清楚哪种变形机制在上地幔中起主导作用，尽管在上地幔中观察到的地震各向异性表明位错蠕变的存在。我们通过3D动力学模型中热边界层的不稳定性检查了岩石圈的热机械侵蚀。这项研究表明，太平洋岩石圈和上地幔的地震衍生热结构对上地幔变形机制施加了重要的约束。上地幔的主要变形机制是位错蠕变，与观测到的地震各向异性一致。可接受的360-540 kJ / mol的活化能范围与实验室研究确定的活化能范围一致，尽管较低。 （c）2005 Elsevier B.V.保留所有权利。

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