Re‐orientation of the extension direction and pure extensional faulting at oblique rift margins: comparison between the Main Ethiopian Rift and laboratory experiments
Re‐orientation of the extension direction and pure extensional faulting at oblique rift margins: comparison between the Main Ethiopian Rift and laboratory experiments
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DOI：
10.1111/ter.12049
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发表时间：
2013-10
期刊：
影响因子：
2.4
通讯作者：
G. Corti;M. Philippon;F. Sani;D. Keir;T. Kidane
中科院分区：
文献类型：
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作者：
G. Corti;M. Philippon;F. Sani;D. Keir;T. Kidane
在这项研究中，我们利用解析良好的断层滑动数据和地震震源机制的独特组合来限制东非倾斜延伸的埃塞俄比亚主裂谷中断层类型的空间变化。这些数据表明，边界断层和内部断层（分别与板块散度（PD）倾斜和正交）都表现出几乎纯粹的倾角滑动运动，并表明裂谷边缘的延伸方向存在显着的局部偏转。比例模拟模型密切复制了裂谷的多学科观察结果，并表明该过程是由根深蒂固的、预先存在的弱点（倾斜于局部放电方向）的存在控制的，该弱点能够导致裂谷边缘延伸方向的局部旋转。正如来自裂谷的现有和新的古地磁数据所支持的，需要进行较小的逆时针块旋转，以适应沿不同断层系统的滑移方向的差异。
In this study, we draw on a unique combination of well‐resolved fault‐slip data and earthquake focal mechanisms to constrain spatial variations in style of faulting in the obliquely extending Main Ethiopian Rift, East Africa. These data show that both boundary and internal faults – oblique and orthogonal to the plate divergence (PD) respectively – exhibit almost pure dip‐slip motion, and indicate significant local deflection in orientation of the extension direction at rift margins. Scaled analogue models closely replicate the multidisciplinary observations from the rift and suggest that the process is controlled by the presence of a deep‐seated, pre‐existing weakness – oblique to the direction of PD – that is able to cause a local rotation in the orientation of the extension direction at rift margins. Minor counterclockwise block rotations are required to accommodate the difference in slip direction along the different fault systems, as supported by existing and new palaeomagnetic data from the rift.