Effects of trench-perpendicular ridge subduction on accretionary wedge deformation: Clues from analogue modelling
Effects of trench-perpendicular ridge subduction on accretionary wedge deformation: Clues from analogue modelling
复制标题
海沟垂直山脊俯冲对增生楔形变形的影响：来自模拟模型的线索
DOI：
10.1002/gj.3317
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发表时间：
2019
影响因子：
1.8
通讯作者：
Cheng Zihua
中科院分区：
文献类型：
--
作者：
Wang Chunyang;Ding Weiwei;Li Jiabiao;Dong Chongzhi;Fang Yinxia;Tang Limei;Ma Letian;Zhao Yanghui;Cheng Zihua
地下室高点（例如，海山和海脊）往往存在于俯冲的大洋板块上。然而，它们对增生楔变形的影响还没有得到很好的理解，特别是洋脊俯冲引起的连续横截面演化过程。为了评估洋脊俯冲对加积楔的影响，运行了模拟模型，以观察平面和横截面视图中的变形过程。结果表明，在平面上，洋脊俯冲导致了一个倒U形隆起区，而海山俯冲总是导致一个圆形隆起区。洋脊和海山俯冲都将导致平面图中的径向扇形走滑断层系统，两翼断层的滑动方向相反。在洋脊俯冲过程中，洋脊轴左翼的断层为左旋，右翼的断层为右旋，这与海山俯冲的断层相反。这可能是由于海山后快速沉降期间上覆沉积物的回流造成的，这将逆转最初沿走滑断层沿着的运动。俯冲脊导致楔状物质从前缘向远侧部分迁移，表现为结构几何学和运动学的变化（例如，楔长度和锥角的减小以及楔高度的增加）。增生棱柱体适应了逆冲断层和逆冲断层发育的锥角变化。我们的模拟结果有助于理解天然洋脊俯冲（如Gagua洋脊和North d'Entrecasteaux洋脊）引起的内部构造变形模式和机制。
Basement highs (e.g., seamounts and ridges) often exist on subducted oceanic plates. However, their effects on the deformation of accretionary wedges have not been well understood, in particular the sequential cross‐sectional evolutionary processes caused by ridge subduction. To evaluate the effects of ridge subduction on accretionary wedges, analogue models were run to observe the deformation processes in both plan and cross‐sectional views. The results show that ridge subduction induces an inverted‐U‐shaped uplifted area, while seamount subduction always causes a circular uplifted area in plan view. Both ridge and seamount subduction will result in a radial fan‐shaped strike‐slip fault system in plan view, with opposite slip directions of the faults in the two wings. During ridge subduction, the faults in the left wing of the ridge axis are sinistral, and those in the right are dextral, which is reverse to that of seamount subduction. This may result from the backward flow in the overlying sediments during the rapid subsidence in the wake of the seamount, which would reverse the initial movement along the strike‐slip faults. The subducted ridge induces migration of wedge material from the frontal margin to the distal part, expressed by changes in structural geometry and kinematics (e.g., reduction in wedge length and taper angle and increase in wedge height). The accretionary prism adapted to the variation of taper angle by the development of back‐thrust faults and out‐of‐sequence thrust fault. Our model results shed lights on understanding the interior structural deformation pattern and mechanism caused by natural cases of ridge subduction, such as Gagua Ridge and North d'Entrecasteaux Ridge.