The style of subduction that prevailed on the early Earth, or even whether subduction was prevalent at all, is an important question in the evolution of Earth's crust, mantle, and surface environment. Here, two‐dimensional numerical convection models, that include grain size evolution to generate weak plate boundaries, reveal a clear transition in subduction behavior with increasing internal heating rate. Sustained subduction with a coherent slab gives way to a style where slabs periodically detach and sink rapidly into the deep mantle, with increasing internal heating rate. In this latter, “drip‐like” subduction regime, repeating cycles of slab growth by subduction, followed by necking and detachment of the lower portion of the slab, are seen. These cycles are termed “slab detachment cycles,” and similar behavior has been seen in regional scale subduction models of the early Earth. Fourier analysis is used to constrain the timescale of slab detachment cycles, and a simple scaling law for this timescale is developed. Applying the scaling law to the early Earth indicates that slab detachment cycles can occur on timescales of <10 Myr, even as low as <5 Myr if the lithosphere is thick and mantle temperature is >1900 K. These cycles may thus be capable of explaining repeating sequences of rocks with “arc” and “non‐arc” signatures seen in some Archean cratons. The drip‐like subduction regime could also have significant implications for the generation of the tonalite‐trondhjemite‐granodiorite (TTG) suite of rocks and exhumation of high pressure metamorphic rocks, two important features of the early Earth geologic record.

中文翻译：

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颗粒破坏对流模型中短期俯冲流行的时间尺度：在太古代构造学中的应用

在早期地球上普遍存在的俯冲方式，甚至俯冲是否普遍存在，都是地球地壳，地幔和地表环境演变的重要问题。在此，二维数值对流模型（包括晶粒尺寸演化以产生薄弱的板块边界）揭示了俯冲行为随内部加热速率增加而发生的明显转变。用连贯的平板进行持续俯冲，让平板逐渐周期性地分离并沉入深层地幔中，同时提高内部加热速率。在后者中，可以看到“滴状”俯冲方式，即通过俯冲来重复平板生长的循环，然后是平板下部的颈缩和脱离。这些循环称为“平板分离循环，”，并且在早期地球的区域尺度俯冲模型中也发现了类似的行为。使用傅里叶分析来约束平板分离周期的时间尺度，并为此时间尺度建立了简单的尺度定律。将比例定律应用于地球早期表明，如果岩石圈较厚且地幔温度为20°C，板坯的脱离周期可以发生在<10 Myr的时间尺度上，甚至低至<5 Myr。> 1900K。因此，这些循环可能能够解释某些太古代克拉通中具有“弧”和“非弧”特征的岩石的重复序列。滴状俯冲机制也可能对斜长白千层-长辉岩-花岗岩-闪长闪长岩（TTG）的产生以及高压变质岩的掘出产生重大影响，这是早期地球地质记录的两个重要特征。