晚第四纪以来东昆仑断裂带东部活动特征及变形机制

In the Northwest of Sichuan, we will research the activity characteristics and the deformation mechanism on the eastern part of the East Kunlun fault zone since late Quaternary. We will use of the high definition image data and the seismotectonic-geomorphology mapping methods. Fault's geometry, the distribution of terraces will get. We will use the deformation of terraces and other landforms to obtain different displacements order of magnitude of faults. We will use the appropriate terrace model and absolute dating of samples to constraint landforms development time and determine. Comparison the slip rates, which get form Paleoseismology and GPS methods, and interpretation the different between them, so slip rates along the main faults may get. Combining with the 3D distribution of earthquake and the deep seismic reflection data, tectonic style of active structures will access. Combining with previous seismicity parameters (e.g., b values) and focal mechanism solution, linear structures, GPS, such as research achievement, discuss the regional stress field, the kinematics characteristics of eastern kunlun fault zone and the mechanism of deformation. This study helps ascertain the earthquake danger of the eastern part of the East Kunlun Fault Zone, the eastward movement features and the deformation mechanism of the East Kunlun Fault Zone and the end-member model of the development of the Qinghai-Tibet Plateau.

基于高清影像数据，运用活动断层填图方法，获得东昆仑断裂带东部相关活动断裂地表平面几何形态、各级阶地分布等数据；以不同阶地变形为重点，兼顾其它各类地质地貌形变，分析多种地貌记录的不同量级的断裂活动量；以适合的阶地模型和多个阶地剖面系列的样品年龄为依据，约束各级阶地的形成、废弃时间，确定各级形变量对应起始时间，进而拟合断裂的活动速率，并对比和解译与古地震方法、GPS方法得到的活动速率的差异及关系；结合前人的地质资料、地震空间分布和深部物理探测成果，讨论东昆仑断裂带东部活动构造的三维几何形态；结合前人的地震活动性参数、震源机制解、线状构造、GPS等研究成果，讨论区域应力场，进而分析东昆仑断裂带东部的运动学特征和变形的机制。本次研究不仅关系到高速左行滑动的东昆仑断裂带东端点的判定，关系到东昆仑断裂带东部地震危险性的判定，也关系到青藏高原东缘变形和演化模型的判定。

东昆仑断裂带是青藏高原内部主要走滑活动断层之一，它东部的活动特征和变形机制是认识东昆仑断裂带不可缺少的一部分，也是认识青藏高原形成机理重要组成部分。在精细的AMS14C测年、DGPS、低空飞行器高分辨率地貌测量基础上，本次研究提出以下主要认识：（1）建立了晚更新世中期以来的高精度地层时间序列的定量化指标，确定了相关地貌面的形成和废弃年龄；（2）结合GPS形变场数据，确定了塔藏断裂的活动性质为全新世活动断层，滑动速率为1~3mm/a，指出了4-11ka的沉积间断是影响滑动速率的主要原因，否定了Kriby et al.(2007)主张的断层滑动速率在塔藏断裂西部接近于0的观点；（3）确定了白龙江-迭部断层的活动时代为晚更新世以来，得到了较小的滑动速率；（4）确定了塔藏断裂古地震事件，分析了历史地震、复发间隔、震级，讨论了地震空区的分布及危险性；（5）讨论了东昆仑断裂带的东端点位于若尔盖盆地以东，东昆仑向东的滑动转变为前缘断裂和岷山隆起，支持刚性块体挤出模型。