Topography of the Overriding Plate During Progressive Subduction: A Dynamic Model to Explain Forearc Subsidence
Topography of the Overriding Plate During Progressive Subduction: A Dynamic Model to Explain Forearc Subsidence
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DOI：
10.1002/2017gl074672
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发表时间：
2017-10-16
影响因子：
5.2
通讯作者：
Strak, Vincent
中科院分区：
文献类型：
--
作者：
Chen, Zhihao;Schellart, Wouter P.;Strak, Vincent
上覆板块地形为俯冲带地球动力学提供了约束条件。我们利用三维摄影测量和粒子图像测速技术，利用俯冲的全动态实验室模型来研究它的演化。模型结果表明，该地区地形特征为弧前动态沉降区，震级尺度为1.44 ~ 3.97km，在弧前沉降区与海沟之间存在局部地形高点。这些地形特征在板坯自由下沉阶段迅速发展，在板坯稳态回滚阶段逐渐减弱。我们认为，这是由于海沟吸力垂直分量沿俯冲带界面的变化造成的，该分量随着深度的增加而逐渐增加，是由于在初始的瞬态沉降阶段，板块逐渐变陡造成的。地幔楔鼻部的向下地幔流对弧前沉降的驱动作用较小。
Overriding plate topography provides constraints on subduction zone geodynamics. We investigate its evolution using fully dynamic laboratory models of subduction with techniques of stereoscopic photogrammetry and particle image velocimetry. Model results show that the topography is characterized by an area of forearc dynamic subsidence, with a magnitude scaling to 1.44-3.97km in nature, and a local topographic high between the forearc subsided region and the trench. These topographic features rapidly develop during the slab free-sinking phase and gradually decrease during the steady state slab rollback phase. We propose that they result from the variation of the vertical component of the trench suction force along the subduction zone interface, which gradually increases with depth and results from the gradual slab steepening during the initial transient slab sinking phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in driving forearc subsidence.