Abstract During extension of the continental lithosphere, rift basins develop. These are often initially offset, and must interact and connect in order to create a continuous rift system that may ultimately achieve break-up. When simulating extensional tectonics and rift interaction structures, analogue and numerical modellers often apply a continuous extension rate along the strike of a rift or rift system. Yet in nature significant extension velocity variations occur along rifts and plate boundaries as a natural consequence of tectonic plates moving apart about a pole of rotation, resulting in rotational extension, and associated rift propagation and structural gradients. Here we present various analogue tectonic experiments to assess rift interaction structures forming in orthogonal extension settings versus rotational extension settings. Our modelling efforts show that rotational extension and orthogonal extension produce significantly different large-scale structures. Rotational extension can cause important variations in rift maturity between rift segments, delay rift interaction zone development, and make rift segments propagate in opposite directions. Still, local features in a rotational extension system can often be regarded as evolving in an orthogonal extension setting. Furthermore, we find that various degrees of rift underlap produce three basic modes of rift linkage structures. Low underlap distance (high angle φ) experiments develop rift pass structures. With increasing underlap distance (φ = ca. 40°), transfer zone basins develop. High degrees of underlap (φ ≤ 30°) tend to result in en echelon sub-basins. Our results match with data from previous modelling efforts and natural examples. We furthermore propose a large-scale tectonic scenario for the East African Rift System based on rotational extension and associated rift propagation. These insights may also be applicable when studying other large-scale rift systems.

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正交和旋转伸展实验中的裂谷段相互作用：对裂谷系统大规模发展的影响

摘要 在大陆岩石圈伸展过程中，裂谷盆地发育。这些通常最初是相互抵消的，并且必须相互作用和连接以创建一个可能最终实现分裂的连续裂缝系统。在模拟伸展构造和裂谷相互作用结构时，模拟和数值建模者通常沿裂谷或裂谷系统的走向应用连续的伸展率。然而，自然界中沿裂谷和板块边界发生显着的伸展速度变化，这是构造板块围绕旋转极移动的自然结果，导致旋转伸展，以及相关的裂谷传播和结构梯度。在这里，我们提出了各种模拟构造实验，以评估在正交伸展设置与旋转伸展设置中形成的裂谷相互作用结构。我们的建模工作表明，旋转延伸和正交延伸会产生明显不同的大型结构。旋转伸展会引起裂谷段之间裂谷成熟度的重大变化，延迟裂谷相互作用带的发育，并使裂谷段向相反方向扩展。尽管如此，旋转扩展系统中的局部特征通常可以被视为在正交扩展设置中演化。此外，我们发现不同程度的裂谷下重叠产生裂谷连接结构的三种基本模式。低重叠距离（大角度φ）实验开发了裂隙通道结构。随着下重叠距离的增加（φ = 大约 40°），传输带盆地发展。高度的下重叠 (φ ≤ 30°) 往往会导致形成梯级子盆地。我们的结果与来自先前建模工作和自然示例的数据相匹配。此外，我们还提出了基于旋转延伸和相关裂谷传播的东非裂谷系统的大规模构造情景。这些见解也可能适用于研究其他大型裂谷系统。