青藏高原北部两条大型断裂晚第四纪活动性的时间变化与对比

One of the hot issues among the active tectonics is how to understand the relationship between the fault slip rates measured from contemporary crustal deformation and that from geological and geomorphological time scale. This issue impacts the study related to regional tectonic dynamics and strong earthquake assessments. We think that researches on the temporal variation of late Quaternary activitis of active faults may provide a solution for this issue. We plan to take two large active strike-slip faults (the Akesay - Shibaocheng segment of the Altyn tagh fault and the Maomaoshan - Laohushan fault) of the northern boundary of the Tibetan Plateau as the target faults in this project. We are going to do field surveys on regular offset landforms from multi time scales since late Quaternary. Trench works will be the new endeavor on measurements and dating from paleoearthquakes and micro-landforms induced by strong earthquakes surface rupture. We will manage to acquire the time serial of strong earthquakes and fault slip rates in various temporal intervals. Integrated analysis for these two faults will be possible on the activities and strong earthquake behaviors. The results will give new constraints on the evolutional characteristics, seismogenic mechanism of strong earthquakes of these large active strike-slip faults along the northern boundary of the Tibetan Plateau. This research will also helpful to understand the deformation mechanism of the northern part of the Tibetan plateau.

目前活动构造研究中最突出的一个问题就是如何理解现今地壳形变测量获得的和晚第四纪地质与地貌获得的两种不同时间尺度断裂滑动速率之间的关系。这一问题也严重影响了对相关构造动力学问题的讨论和地震危险性评价。研究活动断裂晚第四纪以来活动性的时间变化是理解现今地壳形变测量获得的和晚第四纪地质与地貌获得的两种不同时间尺度断裂滑动速率之间关系的可能出路。本项目试图以晚第四纪数万年以来的多时间尺度的常规断错地貌定量观测、强震变形微地貌和古地震的探槽揭露为切入点，尤其是新提出通过强震变形微地貌获取时间分辨率更高的断裂断错数据，以青藏高原北部边界两条典型走滑断裂（阿尔金断裂阿克塞－石包城段和毛毛山－老虎山断裂）为对象，重点研究两条走滑断裂在晚第四纪以来活动性的时间变化和强震行为，并进行两条断裂活动性变化和强震行为对比。进而探讨青藏高原北部边界大型走滑断裂的演化特征、强震孕育与发震以及青藏高原北部的变形机制。