Lithospheric net rotation (LNR) is the movement of the lithosphere as a solid body with respect to the mantle. Separating the signal of LNR from plate tectonic motion is therefore an important factor in producing absolute plate motion models. Net rotation is difficult to constrain because of uncertainties in geological data and outstanding questions about the stability of the mantle plumes used as a reference frame. We use mantle convection simulations to investigate the controlling factors for the magnitude of LNR and to find the statistical predictability of LNR in a fully self-consistent convective system. We find that high lateral viscosity variations are required to produce Earth-like values of LNR. When the temperature dependence of viscosity is lower, and therefore slabs are softer, other factors such as the presence of continents and a viscosity gradient at the transition zone are also important for determining the magnitude of net rotation. We find that, as an emergent property of the chaotic mantle convection system, the evolution of LNR is too complicated to predict in our models. However, we find that the range of LNR within the simulations follows a Gaussian distribution, with a correlation time of 5 Myr. The LNR from the models needs to be sampled for around 50 Myr to produce a fully Gaussian distribution. This implies, that within the time frames considered for absolute plate motion reconstructions, LNR can be treated as a Gaussian variable. This provides a new geodynamic constraint for absolute plate motion reconstructions.

中文翻译：

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使用地球动力学模型约束岩石圈净旋转的范围和变化

岩石圈净旋转（LNR）是岩石圈作为固体相对于地幔的运动。因此，将 LNR 信号与板块构造运动分开是生成绝对板块运动模型的重要因素。由于地质数据的不确定性和关于用作参考框架的地幔柱稳定性的突出问题，净旋转很难约束。我们使用地幔对流模拟来研究 LNR 大小的控制因素，并在完全自洽的对流系统中找到 LNR 的统计可预测性。我们发现需要高横向粘度变化来产生类似地球的 LNR 值。当粘度的温度依赖性较低时，因此板坯较软，其他因素，例如大陆的存在和过渡带的粘度梯度，对于确定净旋转的幅度也很重要。我们发现，作为混沌地幔对流系统的一种新兴特性，LNR 的演化过于复杂，无法在我们的模型中进行预测。然而，我们发现模拟中的 LNR 范围遵循高斯分布，相关时间为 5 Myr。模型中的 LNR 需要采样大约 50 Myr 才能产生完全高斯分布。这意味着，在考虑绝对板块运动重建的时间范围内，LNR 可以被视为高斯变量。这为绝对板块运动重建提供了新的地球动力学约束。