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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 >Seismic characterization of mantle flow in subduction systems: Can we resolve a hydrated mantle wedge?
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Seismic characterization of mantle flow in subduction systems: Can we resolve a hydrated mantle wedge?

机译：俯冲系统中地幔流的地震特征：我们能否解析水合的地幔楔？

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This study provides new constraints on the resolvability of mantle flow in subduction zone settings as inferred by observations of seismic anisotropy. We are motivated by the broad range of shear wave splitting observations in subduction systems that suggest complex flow geometries, changes in the deformation state of mantle minerals, or a combination of both. While shear wave splitting fast polarization directions are typically interpreted as a proxy for flow or maximum finite extension, experimental studies suggest that olivine slip systems change under higher stress and hydration states, conditions likely appropriate for subduction systems. In this study, we predict shear wave splitting as a result of mantle silicate lattice-preferred orientation development in steady-state two-dimensional mantle flow models using a textural development theory that incorporates the combined effects of intracrystalline slip and dynamic recrystallization. We utilize the resulting textures to predict shear wave splitting for populations of seismic raypaths traversing the model within the subduction zone mantle wedge. The results of our study demonstrate that combined observations of variations in fast polarization directions and splitting times make it possible to resolve a shift from anhydrous to hydrous mantle insubduction zone settings provided very good sampling of the mantle wedge. Our models are generally consistent with observed splitting variations for several subduction zones with dense data sampling, including Tonga, Japan, and Kamchatka. The implications of our work suggest that, provided adequate data sampling, shear wave splitting measurements can provide the necessary information to evaluate potential competing effects between variations in mantle flow direction and changes in the stress and hydration states of subduction zone mantle wedges. (c) 2006 Elsevier B.V. All rights reserved.
机译：这项研究为俯冲带环境中地幔流的可分辨性提供了新的限制条件，这是通过地震各向异性的观察得出的。我们受到俯冲系统中剪切波分裂观测的广泛影响，这些观测结果表明复杂的流动几何形状，地幔矿物变形状态的变化或两者兼而有之。虽然剪切波分裂的快速极化方向通常被解释为流量或最大有限延伸的代表，但实验研究表明，橄榄石滑移系统会在较高的应力和水合作用状态下发生变化，而这些条件可能适合于俯冲系统。在这项研究中，我们使用结合晶体内滑移和动态重结晶作用的组织发展理论，预测了稳态二维地幔流模型中地幔硅酸盐晶格优先取向发展的结果，即剪切波分裂。我们利用所得的纹理来预测横切模型在俯冲带地幔楔内穿越的地震射线路径的切变波分裂。我们的研究结果表明，快速极化方向变化和分裂时间的综合观测结果可以解决从无水到地幔俯冲带俯冲带设置的转变，从而提供了很好的地幔楔采样。我们的模型通常与在多个密集俯冲带的俯冲带观测到的分裂变化一致，包括汤加，日本和堪察加半岛。我们工作的意义在于，如果提供足够的数据采样，剪切波分裂测量可以提供必要的信息，以评估地幔流动方向变化与俯冲带地幔楔的应力和水化状态变化之间的潜在竞争效应。 （c）2006 Elsevier B.V.保留所有权利。

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