Three-dimensional finite-element models on the deformation of forearcs caused by aseismic ridge subduction: The role of ridge shape, friction coefficient of the plate interface and mechanical properties of the forearc
Three-dimensional finite-element models on the deformation of forearcs caused by aseismic ridge subduction: The role of ridge shape, friction coefficient of the plate interface and mechanical properties of the forearc
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DOI：
10.1016/j.tecto.2015.12.022
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发表时间：
2016-08
期刊：
影响因子：
2.9
通讯作者：
S. Zeumann;A. Hampel
中科院分区：
文献类型：
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作者：
S. Zeumann;A. Hampel
地质和地球物理资料表明，在无地震洋脊的俯冲过程中，俯冲带的前弧形变强烈。为了更好地了解与凸脊相关的弧前变形模式，我们进行了一系列的三维有限元模型，其中改变了凸脊形状、板界面的摩擦系数和弧前的机械强度。分别对迁移/非迁移隆起和冲积/侵蚀边缘进行了实验研究。我们的结果表明，俯冲山脊抬升了前弧，并产生了水平位移，从而改变了侵蚀型和增积型前弧的应变状态。总体上，海脊前以缩短为主，海脊以上存在缩短和伸展的区域。具有固定脊线的模型仅在脊尖上方显示高的隆起率，而迁移脊线上的前弧在前脊侧翼上方经历隆起，随后在后翼上方下沉。凸脊的高度和宽度以及板材界面的摩擦系数对弧前变形模式的影响最大，而弧前的机械强度对弧前变形的影响较小。对于高和宽脊、高摩擦系数和/或弱弧前材料，沟槽处的弧前压痕最大。高脊和窄脊的前弧在山脊以上的缩短和伸展更为强烈。我们的模型结果提供了有关山脊引起的位移和应变场分布的信息，从而有助于识别自然界中俯冲无震脊引起的变形模式。
Geological and geophysical data show that the forearc of subduction zones experiences strong deformation during the subduction of aseismic oceanic ridges. In order to better understand ridge-related forearc deformation patterns, we performed a series of three-dimensional finite-element models, in which we varied the ridge shape, the friction coefficient of the plate interface and the mechanical strength of the forearc. Experiments were carried out for migrating/non-migrating ridges and accretive/erosive margins, respectively. Our results show that the subducting ridge uplifts the forearc and induces horizontal displacements that alter the strain regime of both erosive and accretive forearcs. Generally, shortening prevails in front of the ridge, while domains of shortening and extension exist above the ridge. Models with stationary ridges show high uplift rates only above the ridge tip, whereas the forearc above migrating ridges experiences uplift above the leading ridge flank and subsequent subsidence above the trailing flank. The height and width of the ridge as well as the friction coefficient of the plate interface have the largest effect on the forearc deformation patterns, whereas the mechanical strength of the forearc plays a lesser role. Forearc indentation at the trench is largest for high and broad ridges, high friction coefficients and/or weak forearc material. Shortening and extension of the forearc above the ridge are more intense for high and narrow ridges. Our model results provide information about the distribution of ridge-induced displacements and strain fields and hence help to identify deformation patterns caused by subducting aseismic ridges in nature.