Abstract In rift settings, extension rates often vary along strike, due to rotation about a vertical axis or Euler pole, yet tectonic modelers traditionally apply constant along-strike deformation rates. Here we compare rift development and propagation under traditional orthogonal extension versus rotational extension conditions. The set-ups involve brittle-viscous layering and localize deformation through structural weaknesses (seeds). Our models provide first-order insights into the differences in rift development between both boundary conditions: orthogonal extension produces a rift basin with constant synchronous along-strike features, whereas rotational extension induces along-strike structural gradients, diachronous rift development causing rift propagation and the development of V-shaped basins. We observe important viscous flow associated with differential pressure gradients in rotational extension. We also describe the important effects of strain partitioning between rift axis and model boundaries, the quantifying of which is crucial to avoid incorrect model interpretations. Although our model results are first-order only, they are in good agreement with various natural examples and previous modeling studies and highlight the importance of considering the third dimension when studying tectonic systems.

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旋转与正交扩展中的裂隙传播：来自 4D 模拟模型的见解

摘要在裂谷环境中，由于绕垂直轴或欧拉极的旋转，延伸率通常沿走向而变化，但构造建模者传统上应用恒定的沿走向变形率。在这里，我们比较了传统正交伸展与旋转伸展条件下的裂谷发展和传播。设置涉及脆性粘性分层和通过结构弱点（种子）局部变形。我们的模型提供了两种边界条件之间裂谷发育差异的一阶见解：正交伸展产生具有恒定同步沿走向特征的裂谷盆地，而旋转伸展引起沿走向结构梯度，历时裂谷发育导致裂谷传播和V型盆地的发展。我们观察到与旋转延伸中的压差梯度相关的重要粘性流。我们还描述了裂谷轴和模型边界之间应变划分的重要影响，其量化对于避免错误的模型解释至关重要。尽管我们的模型结果仅为一阶，但它们与各种自然实例和先前的建模研究非常吻合，并突出了在研究构造系统时考虑三维的重要性。