基于不同时间尺度约束的东昆仑断裂东段运动学特征研究

Based on the research methods at ten thousand year scale, the Millennium scale and the ten year scale, the slip rate of eastern segments of East Kunlun fault is restrained: using the interpretation of remote sensing images and digital elevation models of multi resolutions, to measure the offsets of the river terrace risers on different terrace levels, we will analyze the abandoned and beginning ages of upper terraces and lower terraces to limit the starting age for terrace risers, and study the suitability of the abandoned age of upper and lower terrace and the beginning age of lower terrace on different type of river terraces, by the unified terraces age standards and erosion situation to calculate the slip rate of the eastern segments in past ten thousand years; then, several trench sites will be selected where there is continuous sediments, according to the cycle period and offset of the earthquake, a slip rate in past thousand years can be estimated; finally, along eastern segments at offset terrace riser observation points corresponding to the location of each selected satellite orbits through the area, the slip rate of the segments actived in recent ten years will be measured by using the differential stacking interferometric synthetic aperture radar technology. The results obtained by above methods will be used to analyze the strike-slip rate variation of the Kunlun fault and to constrain the Tibet Plateau internal material flowing mechanism. Thus we can clear the effects of the strike-slip fault in the tectonic evolution of the Tibetan Plateau and the transition from strike-slip to thrust in upper crust that is on the top of middle and lower crust flow, and discuss the dynamics model of the deformation of the Tibetan Plateau.

综合应用万年尺度、千年尺度和十年尺度下的研究方法，对东昆仑断裂东段的走滑速率进行约束：基于不同分辨率遥感和数字高程模型的解译，对多级错断河流阶地陡坎进行测量，研究用上阶地面废弃年龄、下阶地面形成年龄和下阶地面废弃年龄方法来限定错断阶地陡坎起始年龄在不同类型的河流阶地中的适用情况，根据河流侧向侵蚀状况采用不同阶地面年龄对各段的万年尺度走滑速率进行计算；其次选取具有连续沉积物的地点开挖探槽，依据古地震复发周期和同震位移量来约束东昆仑断裂千年尺度的活动速率；再选取相应的卫星轨道数据，运用多时相合成孔径雷达差分干涉叠加技术测量该段近十年来断裂的走滑速率。对比三种方法得到的结果，分析昆仑断裂向东走滑速率变化特征及对青藏高原内部物质流动的制约机理，明确走滑断裂在青藏高原构造演化中的作用，阐明在中下地壳流体作用下，由断层分割的上地壳块体逆冲转换的运动学特征，探讨青藏高原变形的动力学模型。

通过对横穿东昆仑断裂东段的各类河流阶地进行系统观测，总结出了河流对上下游阶地陡坎的侵蚀作用：在河流下游侧被错开远离河道的阶地被保留；被错入河道的阶地被保留，而另一侧全部被侵蚀；上下游阶地全部被侵蚀，只有下游远离河道的被保留；断层有一定的垂向运动。分析上阶地面废弃年龄方法、下阶地面废弃年龄方法在不同类型的河流阶地中的适用情况，结合阶地年龄数据，断裂的走滑速率进行计算。运用合成孔径雷达差分干涉叠加测量技术分析了该段近年来断裂的走滑速率。通过三维软件处理无人机在现场收集的数据，获得了门源地震的地面的数字高程模型、正射影像和3D模型。这为研究表面断裂提供了丰富的数据库，从中可以测量表面断裂模式和位移。D-InSAR结果和现场调查表明，这场地震导致160多公里的同震地表沿预先存在的断层痕迹破裂。本次地震地表观测到的水平偏移量一般小于2米，垂直偏移量小于1米，断层主要表现为左旋走滑运动。玛多地震导致地表变形带形成大量砂土液化特征。构造应力、震动和水力压裂以及动物活动为液化砂提供了迁移通道。根据产生砂土特征的不同流动路径，将砂土液化分为四种不同的形态。第一种形态是由液化砂从主表面破裂区域形成的大裂缝中喷出形成的。第二种形态的特征是，从主表面断裂带外发育的小剪切断裂喷出的砂呈雁列分布。第三种形态的特征是，软弱层下方的砂通过振动和水力压裂液化并喷出，形成独立的砂锥和圆形凹坑。第四种形态的特征是老鼠洞为液化沙的喷发提供了通道。分析了昆仑断裂向东走滑速率变化特征及对青藏高原内部物质流动的制约机理，明确了走滑断裂在青藏高原构造演化中的作用，阐明了在中下地壳流体作用下，由断层分割的上地壳块体逆冲转换的运动学特征，探讨了青藏高原变形的动力学模型。