Rapid rotation of normal faults due to flexural stresses: An explanation for the global distribution of normal fault dips
Rapid rotation of normal faults due to flexural stresses: An explanation for the global distribution of normal fault dips
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DOI：
10.1002/2013jb010512
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发表时间：
2014-04-01
影响因子：
3.9
通讯作者：
Behn, Mark D.
中科院分区：
文献类型：
--
作者：
Olive, Jean-Arthur;Behn, Mark D.
我们提出了一个力学模型来解释为什么大多数地震活跃的正断层的倾角（30-60度）比安德森-拜尔利理论（60-65度）预期的要低得多。我们的模型建立在经典的有限延伸理论，但纳入了旋转的活动断层面作为响应的弯曲应力的积累与增加扩展。我们假设，断层面的旋转行为，以尽量减少所需的拉伸工作量，以维持在故障上的滑动。在弹性层中，这一假设导致在断层隆起达到断层厚度的50%之前，活动断层面从大约60度快速旋转到30-45度。在强度有限的断层层中，会发生相应的但总体上较慢的旋转。断层旋转率的规模作为断层层厚度的倒数，这是在定量协议与2-D地球动力学模拟，包括岩石圈的弹塑性描述。我们发现，断层旋转促进寿命更长的断层延伸相比，继续滑动的高角度的正断层，并讨论了这种机制的影响，在大陆裂谷系统和海洋扩张中心的断层演化。
We present a mechanical model to explain why most seismically active normal faults have dips much lower (30-60 degrees) than expected from Anderson-Byerlee theory (60-65 degrees). Our model builds on classic finite extension theory but incorporates rotation of the active fault plane as a response to the buildup of bending stresses with increasing extension. We postulate that fault plane rotation acts to minimize the amount of extensional work required to sustain slip on the fault. In an elastic layer, this assumption results in rapid rotation of the active fault plane from similar to 60 degrees down to 30-45 degrees before fault heave has reached similar to 50% of the faulted layer thickness. Commensurate but overall slower rotation occurs in faulted layers of finite strength. Fault rotation rates scale as the inverse of the faulted layer thickness, which is in quantitative agreement with 2-D geodynamic simulations that include an elastoplastic description of the lithosphere. We show that fault rotation promotes longer-lived fault extension compared to continued slip on a high-angle normal fault and discuss the implications of such a mechanism for fault evolution in continental rift systems and oceanic spreading centers.