Subduction style is controlled by a variety of physical parameters. Here we investigate the effect of subducting plate length on subduction style using laboratory experiments of time‐evolving buoyancy‐driven subduction in 3‐D space. The investigation includes two experimental sets, one with a lower (~740) and one with a higher (~1,680) subducting plate‐to‐mantle viscosity ratio (η_SP/η_M). Each set involves five models with a free‐trailing‐edge subducting plate and variable plate length (20–60 cm, scaling to 1,600–4,800 km), and one model with a fixed‐trailing‐edge subducting plate representing an infinitely long plate. Through determining the contact area between subducting plate and underlying mantle, plate length affects the resistance to trenchward motion of the subducting plate and thus controls the partitioning of the subduction velocity (v_S) into the subducting plate velocity (v_SP) and trench velocity (v_T). This subduction partitioning thereby determines the subduction style by controlling the dip angle of the slab tip once it first touches the 660 km discontinuity. The low η_SP/η_M models display two subduction styles. Short plates (≤40 cm) induce a higher subduction partitioning ratio (v_SP/v_S), promoting trench advance and slab rollover geometries, whereas longer plates (≥50 cm) lead to a lower v_SP/v_S, producing continuous trench retreat and backward slab draping geometries. In contrast, the high η_SP/η_M models exclusively show trench retreat with draping geometries, as the high η_SP/η_M enables less slab bending before its tip touches the 660 km discontinuity. Our study indicates that future modeling work should consider the effects of plate length on the style and evolution of subduction.

中文翻译：

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板长对俯冲运动学和板几何的影响：浮力驱动模拟俯冲模型的启示

俯冲方式受多种物理参数控制。在这里，我们使用3D空间中随时间变化的浮力驱动的俯冲的实验室实验研究了俯冲板长度对俯冲方式的影响。调查包括两个实验组，一个具有较低的（〜740）和一个具有较高（〜1680）俯冲板到地幔粘度比（η _SP / η_中号）。每套模型都包括五种模型，它们具有无尾缘的俯冲板和可变的板长（20–60 cm，缩放至1,600–4,800 km），而另一种模型具有固定尾缘的俯冲板，其代表无限长的板。通过确定俯冲板和下伏地幔之间的接触面积，板长会影响到俯冲板向沟槽运动的阻力，从而控制俯冲速度（v _S）到俯冲板速度（v _SP）和沟槽速度（v _T）。因此，这种俯冲分区通过首先控制平板尖端接触660 km不连续点的倾角来确定俯冲样式。低η_SP / η_中号模型显示两个俯冲风格。短板（≤40 cm）引起更高的俯冲分配比（ v _SP / v _S），促进沟槽前进和平板翻转几何形状，而长板（≥50 cm）导致v _SP / v _S降低，从而产生连续沟槽后退和后板悬垂几何形状。相比之下，高η _SP / η_中号模型进行展示与悬垂几何形状的沟槽撤退，作为高η _SP / η_中号在其尖端接触到660 km的不连续点之前，可减少板坯弯曲。我们的研究表明，未来的建模工作应考虑板长对俯冲样式和演化的影响。