Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra‐oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the onset and operation of plate tectonics in the early and, to a lesser degree, modern Earth. On the contrary, the initiation of intra‐continental subduction still remains underappreciated. Here we provide an overview of 1) observational evidence for upwelling of hot mantle material flanked by downgoing proto‐slabs of sinking continental mantle lithosphere, and 2) previously published and new numerical models of plume‐induced subduction initiation. Numerical modeling shows that under the condition of a sufficiently thick (>100 km) continental plate, incipient downthrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies of moderate temperatures and without significant strain‐ and/or melt‐related weakening of overlying rocks. This finding is in contrast with the requirements for plume‐induced subduction initiation within oceanic or thinner continental lithosphere. As a result, plume‐lithosphere interactions within continental interiors of Paleozoic‐Proterozoic‐(Archean) platforms are the least demanding (and thus potentially very common) mechanism for initiation of subduction‐like foundering in the Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in various intra‐continental areas. A better understanding of the role of intra‐continental mantle downthrusting and foundering in global plate tectonics and, particularly, in the initiation of “classic” ocean‐continent subduction will benefit from more detailed follow‐up investigations.

中文翻译：

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羽状内陆岩石圈地幔下沉：俯冲引发的一个被忽视的机制？

尽管已经提出了许多不同的俯冲引发机制，但在与数值实验的一致性和可再现性方面，只有少数可行。特别是，最近已证明，由上升的地幔羽流引发的洋内俯冲作用可能在早期以及现代程度较小的现代地球上，对板块构造的开始和运行有很大贡献。相反，大陆内俯冲的启动仍未得到充分认识。在这里，我们提供了以下方面的概述：1）观测的证据表明，热的地幔物质上升，两侧是下沉的大陆地幔岩石圈下沉的原型板； 2）先前发表的羽状俯冲引发的新数值模型。数值模拟表明，在大陆板足够厚（> 100 km）的情况下，中等温度的羽流异常可能触发岩石最下层地幔水平的初期下冲，而没有明显的应变和/或与熔体有关的减弱上覆的岩石。这一发现与在海洋或更薄的大陆岩石圈内羽状俯冲引发的要求相反。结果，古生代-元古生代（Archean）陆架内部内部的羽-岩圈相互作用是在生代地球中引发俯冲样沉陷的要求最低的机制（因此可能是非常普遍的）。我们的发现得到了不断增长的在各个洲内地区收集的新地球物理数据的支持。