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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Some thoughts on the stability of cratonic lithosphere: Effects of buoyancy and viscosity
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Some thoughts on the stability of cratonic lithosphere: Effects of buoyancy and viscosity

机译：关于克拉通岩石圈稳定性的一些思考：浮力和粘度的影响

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摘要

Continental cratons have not experienced major tectonic disruptions over a timescale of 10~9 years. The thickness of cratonic lithosphere also appears to have changed little over this timescale. These observations are often attributed to the presence of chemically buoyant and/or highly viscous subcratonic roots. Simple physical scaling relationships are developed to explore the buoyancy and/or viscosity conditions required to stabilize such roots against large-scale deformation and rapid remixing into the mantle. The scalings are tested using idealized numerical simulations with good general agreement. Applied to Earth, the scalings suggest that (1) buoyancy alone is unlikely to stabilize cratonic roots and (2) if root viscosity is to provide stability into the Archean, then roots must be 10~3 times as viscous as the mantle. Based on available experimental data, root dehydration cannot account for the required viscosity increase. Temperature-dependent viscosity can stabilize roots, but it does so at the expense of stagnating the entire mantle lithosphere, i.e., at the expense of sacrificing plate tectonics. This suggests that the plastic yielding properties of rocks at low temperatures will need to be more directly accounted for in future experiments exploring root stability.
机译：大陆克拉通在10到9年的时间内没有经历过重大的构造破坏。在这段时间内，克拉通岩石圈的厚度似乎也没有变化。这些观察结果通常归因于化学上漂浮的和/或高粘性的亚克拉通根的存在。开发了简单的物理比例关系，以探索使此类根部稳定以抵抗大规模变形和快速重新混入地幔所需的浮力和/或粘度条件。使用具有良好总体一致性的理想化数值模拟来测试缩放比例。应用于地球的结垢表明，（1）单独的浮力不太可能稳定克拉通的根部;（2）如果要通过根部粘度为太古宙岩提供稳定性，则根部的粘性必须是地幔的10到3倍。根据可用的实验数据，根部脱水无法解决所需的粘度增加。与温度有关的粘度可以使根部稳定，但是这样做却以使整个地幔岩石圈停滞为代价，即以牺​​牲板块构造为代价。这表明在未来探索根系稳定性的实验中，将需要更直接地考虑低温下岩石的塑性屈服特性。

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