Tectonic and geomorphological evolution of forearcs during ridge subduction

海底海脊的俯冲导致上板块的相当大的抬升和变形，并可能导致近海的前弧和陆上的凹陷，形成不同的断层模式，形成海洋阶地，并使俯冲海脊以上的河流偏转。根据海脊相对于板块会聚方向的方向，海脊可能是静止的，也可能沿着边缘移动，导致一波弧前隆起和随后的下沉。在这里，我们建议使用3D数值模型来研究受海脊俯冲影响的前弧的构造和地形演化。使用不同的模型设置，我们将分别区分增长/侵蚀边缘和迁移/非迁移山脊。我们将改变前圆弧和钢板界面的脊形和机械强度，以确定最有影响的参数。结果将从山脊引起的弧前几何、位移和应力场的变化来分析。为了研究山脊俯冲对弧前地貌演化的影响，构造模型将与景观演化模型相耦合。模拟的地貌将揭示俯冲山脊是否会导致海岸附近的河流偏转。我们将把我们的发现与纳斯卡海脊(沿着侵蚀的秘鲁边缘迁徙)、科科斯海脊(俯冲到侵蚀性的中美洲边缘之下)和加瓜海脊(沿着增生的琉球岛弧迁徙)的碰撞带进行比较。

Subduction of submarine ridges causes considerable uplift and deformation of the upper plate and may lead offshore to the indentation of the forearc and onshore to the development of distinct patterns of faulting, the formation of marine terraces and the deflection of rivers above the subducting ridge. Depending on the orientation of the ridge relative to the plate convergence direction, the ridge may either be stationary or migrate along the margin, causing a wave of forearc uplift and subsequent subsidence. Here we propose to use 3D numerical models to investigate the tectonic and topographic evolution of forearcs affected by ridge subduction. Using different model setups we will distinguish between accretive/erosive margins and migrating/non-migrating ridges, respectively. We will vary the ridge shape and the mechanical strength of the forearc and the plate interface to identify the most influential parameters. The results will be analysed with respect to the ridge-induced changes of the forearc geometry, displacement and stress field. To investigate the impact of ridge subduction on the geomorphological evolution of the forearc, the tectonic models will be coupled to a landscape evolution model. The modelled landscapes will reveal if a subducting ridge may lead onshore to the deflection of rivers near the coast. We will compare our findings with the collision zones of the Nazca Ridge (migrating along the erosive Peruvian margin), the Cocos Ridge (subducting stationary beneath the erosive Central American margin) and the Gagua Ridge (migrating along the accretive Ryukyu island arc).