The relatively short duration of the early stages of subduction results in a poor geological record, limiting our understanding of this critical stage. Here, we utilize a 2-D numerical model of incipient subduction, that is the stage after a plate margin has formed with a slab tip that extends to a shallow depth and address the conditions under which subduction continues or fails. We assess energy budgets during the evolution from incipient subduction to either a failed or successful state, showing how the growth of potential energy and slab pull, is resisted by the viscous dissipation within the lithosphere and the mantle. The role of rheology is also investigated, as deformation mechanisms operating in the crust and mantle facilitate subduction. In all models, the onset of subduction is characterized by high lithospheric viscous dissipation and low convergence velocities, whilst successful subduction sees the mantle become the main area of viscous dissipation. In contrast, failed subduction is defined by the lithospheric viscous dissipation exceeding the lithospheric potential energy release rate and velocities tend towards zero. We show that development of a subduction zone depends on the convergence rate, required to overcome thermal diffusion and to localize deformation along the margin. The results propose a minimum convergence rate of ∼0.5 cm yr⁻¹ is required to reach a successful state, with 100 km of convergence over 20 Myr, emphasizing the critical role of the incipient stage.

中文翻译：

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俯冲成功与失败的时间尺度：数值建模的见解

俯冲早期阶段的时间相对较短，导致地质记录不佳，限制了我们对这一关键阶段的理解。在这里，我们利用初始俯冲的二维数值模型，这是板缘形成具有延伸至浅深度的板状尖端并解决俯冲持续或失败的条件之后的阶段。我们评估了从初始俯冲到失败或成功状态演变过程中的能量预算，显示了势能和平板拉力的增长如何受到岩石圈和地幔内部粘性耗散的阻碍。还研究了流变学的作用，因为在地壳和地幔中起作用的变形机制促进了俯冲作用。在所有型号中 俯冲的开始具有高岩石圈粘性耗散和收敛速度低的特点，而成功的俯冲使地幔成为粘性耗散的主要区域。相反，失败的俯冲是指岩石圈的粘性耗散超过岩石圈的势能释放速率，速度趋于零。我们显示出俯冲带的发展取决于收敛速率，克服了热扩散和沿边缘局部变形所需的收敛速率。结果表明最低收敛速度为〜0.5 cm年 失败的俯冲是指岩石圈的粘性耗散超过岩石圈的势能释放速率，速度趋于零。我们显示出俯冲带的发展取决于收敛速度，克服了热扩散并使变形沿边缘局部化所需。结果表明最低收敛速度为〜0.5 cm年 失败的俯冲是指岩石圈的粘性耗散超过岩石圈的势能释放速率，速度趋于零。我们显示出俯冲带的发展取决于收敛速度，克服了热扩散并使变形沿边缘局部化所需。结果表明最低收敛速度为〜0.5 cm年要达到成功的状态，需要^-1，在20 Myr上有100 km的会聚，强调了初期阶段的关键作用。