Most subduction zones on Earth are oblique, i.e., the angle between the plate convergence vector and the trench notably differs from 90°. Therefore, modeling and understanding the strain partitioning in the forearc, the development of extensional basins in the back-arc region and the diachronous transition from subduction to collision require a 3D approach. Here, we assess how oblique oceanic subduction and subsequent collision and associated mantle flow around the subducted lithosphere control the thermo-mechanical evolution of active margins. We conducted a series of 3D thermo-mechanical subduction models and discuss the influence of different subduction obliquity angles, the role of mantle flow variations and their connection with sediment transport and back-arc deformation. Numerical models are complemented by scaled analogue models to visualize the mantle flow evolution. Oceanic subduction along an oblique trench results in asymmetric mantle return flow leading to the gradual decrease of the subduction obliquity angle driven by the gradual rotation of the lower plate and the along-trench variation of slab retreat. This creates laterally variable subduction velocities and slab geometries. Back-arc extension is governed by both the toroidal mantle flow along the slab edges and by the oblique subduction induced lateral mantle flow gradient. The diachronous transition from oceanic to continental subduction and collision facilitates the laterally variable trench advance and retreat and back-arc deformation. Tectonically induced lateral sediment transport in the trench and along the subduction interface decreases its strength and viscosity and can alter subduction velocities. Our model results provide critical insights into the evolution of oblique subduction and collisional systems, such as the Arabia-Eurasia convergence zone.

地球上大多数俯冲带都是倾斜的，即板块会聚矢量与海沟之间的夹角明显不同于90°。因此，建模和理解弧前的应变分配、弧后区域伸展盆地的发展以及从俯冲到碰撞的历时过渡需要 3D 方法。在这里，我们评估了倾斜的海洋俯冲和随后的碰撞以及俯冲岩石圈周围相关的地幔流如何控制活动边缘的热机械演化。我们进行了一系列 3D 热机械俯冲模型，并讨论了不同俯冲倾角的影响、地幔流变化的作用及其与沉积物输送和弧后变形的联系。数值模型由比例模拟模型补充，以可视化地幔流演化。大洋沿斜海沟俯冲导致地幔回流不对称, 导致下板块逐渐旋转和板片后退沿海沟变化驱动的俯冲倾角逐渐减小。这会产生横向可变的俯冲速度和板片几何形状。弧后延伸受沿板片边缘的环形地幔流和倾斜俯冲引起的侧向地幔流梯度控制。从海洋到大陆的俯冲和碰撞的历时过渡促进了横向变化的海沟进退和弧后变形。海沟中和沿俯冲界面的构造引起的横向沉积物输送降低了其强度和粘度，并可以改变俯冲速度。我们的模型结果提供了对倾斜俯冲和碰撞系统演化的重要见解，例如阿拉伯-欧亚大陆辐合带。