与大型走滑断裂相关的旋转

与大型走滑断裂有关的旋转一方面起因于断裂带的大规模走滑,另一方面也与大断裂带内部及外围次级断裂系的水平运动密切相关.尽管前人提出了一些有关断裂带走滑与旋转的动力学模式,但由于不同走滑断裂系变形环境及边界条件的差异,断裂走滑导致块体旋转的机制是非常复杂的,很难用统一的动力学模式来解释.对美国西海岸圣安德列斯断裂、美国盆岭区Lake Mead断裂系、中国西南哀牢山-红河走滑断裂系以及新西兰Alpine断裂带、土耳其北安那托利亚断裂等的研究结果均表明,在断裂带走滑过程中,相关构造及块体的旋转非常明显.运用古地磁学、磁组构、构造分析、高精度GPS监测及构造模拟等方法,可以对这些构造及块体的旋转方向和幅度进行研究.由于大规模旋转会导致构造格局及地质地貌特征的改变,因此在走滑断裂带的研究中必须加以重视.

A Review on Tectonic Rotations Related to Large Strike-Slip Faults

The rotations is produced not only by the large movement of the main strike-slip fault,but also by the horizontal movement of the secondary faults within the main fault or in the adjacent area.Although some dynamic models have been proposed to illustrate the relationship between vertical axis rotations and fault slips,it is very difficult to find a simple model to explain the mechanism of the rotations and strike-slip fault systems because of the difference of the deformation environment and boundary conditions in different strike-slip fault systems.In many strike-slip tectonic settings,rotations of faults and blocks have been inferred from both laboratory modeling and field geological surveys.Studies show that tectonic rotations related strike-slip faults are very distinct in the areas such as the western coast near the San Andreas fault,the Lake Mead fault in the Basin and Range Province in the United States,the Ailaoshan-Red River fault in Southeast China,the Alpine fault in New Zealand and the Northern Anatolian fault in Turkey.The methods of paleomagnetism,magnetic fabric,tectonic analysis,high-accuracy GPS monitoring and tectonic modeling can be used to identify these rotations,but the combination of the methods are very important to get a reliable result.Much attention should be paid to the tectonic regime and geography changes resulted from tectonic and block rotations during the study of the strike-slip faults,especially the large-scale strike-slip fault systems.