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    秦岭造山带北缘的斜向碰撞与汇聚因子

    Oblique collision and convergence factor on the northern margin of the Qinling orogenic belt

    • 摘要: 提要:秦岭北缘洛南—栾川断裂带是华北板块南缘与秦岭造山带汇聚-拼合带,具有SW→NE向俯冲兼左旋走滑的性质,并构成叠瓦状构造和双重构造的组合样式。秦岭北缘不同性质的构造组成有规律的图案,其展布方位和运动学方式与板块汇聚的动力学特征极为吻合。变形分析结果表明,区内变形岩石主要是中上地壳的产物,岩石有限应变的三轴比为:X∶Y∶Z=8.86∶4.32∶1,应变椭球体为扁椭球状。汇聚因子是:在洛南地区板块汇聚方向为22 °,汇聚方向与板块边界的夹角为73 °;在栾川地区板块汇聚方向为31 °,汇聚方向与板块边界的夹角为82 °,显示出秦岭造山带与华北板块南缘的碰撞和拼合具有典型的斜向汇聚特征。

       

      Abstract: Abstract:The Luonan-Luanchuan fault zone on the northern margin of the Qinling Mountains is a convergence belt between the North China plate and Qinling orogenic belt with the natures of SW-NE-directed subduction and sinistral strike-slip motion. It shows an association style of imbricate structure and duplex structure. The structures of different natures on the northern margin of the Qinling Mountains make up a regular pattern, with their distribution direction and kinematic mode coinciding with the kinematic features of the convergence plate. The results of deformation analysis indicate that the deformed rocks in the area are mainly the product of the middle and upper crust. The triaxial ratio of rock finite strain is X∶Y∶Z = 8.86∶4.32∶1 and the strain ellipsoid is flat-ellipsoidal. The convergence factors are as follows: in the Luonan area the direction of plate convergence is 22° and the angle between the plate convergence direction and plate boundary is 73° and in the Luanchuan area the direction of plate convergence is 31° and the angle between the plate convergence direction and plate margin is 82°. This shows that the collision and convergence between the Qinling orogenic belt and the southern margin of the North China plate have the typical features of oblique convergence.

       

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