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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 >B-type olivine fabric in the mantle wedge: Insights from high-resolution non-Newtonian subduction zone models
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B-type olivine fabric in the mantle wedge: Insights from high-resolution non-Newtonian subduction zone models

机译：地幔楔中的B型橄榄石织物：高分辨率非牛顿俯冲带模型的见解

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摘要

Several hypotheses have been proposed to explain trench-parallel shear wave splitting in the mantle wedge of subduction zones. These include 3-D flow effects, parallel melt filled cracks, and B-type olivine fabric. We predict the distribution of B-type and other fabrics with high-resolution thermal and stress models of subduction zones. A composite viscous rheology is used that incorporates wet diffusion creep, wet dislocation creep, and a stress-limiting approximated Peierls creep law. Rheological parameters for dislocation and diffusion creep are based on deformation experiments. The effects of variable viscous coupling between the slab and mantle are explored using kinematic boundary conditions that change along the top of the slab. Two end-member models are observed, which depend on the depth of partial viscous coupling between the slab and mantle: (1) deep partial coupling which gives rise to cold, high-stress conditions in the forearc mantle and high-temperature, low-stress conditions in the arc and back-arc mantle (2) full viscous coupling at the base of a 40 km conducting lid which is characterized by high temperature and low stress. The case with deep partial coupling, which produces a better match with attenuation tomography and heat flow, shows a large region with suitable conditions for B-type fabric in the forearc mantle and a rapid transition toward the back-arc to conditions that are more suitable for A-, C-, or E-type fabrics. Full viscous coupling gives rise to high-temperature, low-stress conditions unsuitable for B-type fabric. Our modeling predicts that the best candidates for regions with B-type fabric are the forearc mantle and a cold 10-15 km layer above the slab. (c) 2005 Elsevier B.V. All rights reserved.
机译：已经提出了几种假说来解释俯冲带地幔楔中的沟槽平行剪切波分裂。这些包括3-D流动效应，平行的熔融填充裂缝和B型橄榄石织物。我们用俯冲带的高分辨率热力和应力模型预测了B型和其他织物的分布。使用了复合粘性流变学，其中包括湿扩散蠕变，湿位错蠕变和应力极限近似Peierls蠕变定律。位错和扩散蠕变的流变参数基于变形实验。使用沿平板顶部变化的运动边界条件，研究了平板与地幔之间的可变粘性耦合作用。观察到两个端部构件模型，它们取决于板与地幔之间的部分黏性耦合的深度：（1）深部局部耦合，这会导致前臂地幔中的寒冷，高应力条件以及高温，低应力弧形和后弧地幔中的应力条件（2）在40 km导电盖的底部完全粘滞耦合，其特征在于高温和低应力。具有深局部耦合的情况可以更好地与衰减层析成像和热流匹配，显示出一个较大的区域，该区域具有适合前臂地幔中B型织物的条件，并且可以快速向后弧过渡到更适合的条件适用于A，C或E型面料。充分的粘性耦合会导致不适合B型织物的高温，低应力条件。我们的模型预测，B型织物区域的最佳候选者是前臂地幔和平板上方10-15 km的冷层。 （c）2005 Elsevier B.V.保留所有权利。

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