青藏高原中部格仁错断裂晚第四纪以来（垂直）活动特征及其构造意义

Late Quaternary activities of the Gyaring Co fault (GCF) is very vital to understand the regional kinematics and deformation models of central Tibet. Due to hard fieldwork conditions in the central Tibetan Plateau, remote sensing image has been intensively used to investigate the horizontal movements of the strike-slip fault, while little information on vertical aspects. We have estimated the strike-slip rate along the GCF, and now realized its accompanying vertical component along the whole fault. Here we plan to take the advantages of the displaced lakeshore landforms along both sides of the GCF to study its vertical movement. Based on previous classification of the lakeshore landforms, we will use integrated technologies of stereo images pairing, differential GPS and Unmanned Aerial Vehicle photogrammetry to recover the distribution of vertical displacements. Meanwhile, we will date lakeshore landforms mainly by Optical Stimulated Luminescence and Cosmogenic Nuclide exposure dating. Then we will reconstruct the history of vertical slip of the GCF recorded by lakeshore landforms and estimate the vertical slip rates since the late Quaternary. Finally, we will obtain the temporal and spatial distribution of vertical slip rates of the GCF and the partitioning between horizontal and vertical movements. This proposed application is expected to provide key data to estimate the geometry and kinematic relationship between GCF-Wuru Co fault conjugate strike-slip fault system and Xainza normal fault system and to understand the mechanism of vertical movements along the GCF, which is important for us to understand tectonic deformation in central Tibet.

格仁错断裂晚第四纪活动研究是认识和理解青藏高原中部构造运动图像和变形模式的重要环节。高原中部野外工作条件差，多借助遥感影像重点研究走滑运动，关注垂直运动的研究有限。申请者已系统地获取了格仁错断裂的走滑速率，注意到断裂整体存在正断层运动。断裂切过系列大湖，开展垂直运动定量研究具有优势。本研究拟选择断层两侧广泛分布的古湖滨线和湖蚀台地为研究对象；依据湖岸地貌分期结果，采用卫星影像立体像对、差分GPS和无人机摄影测量等技术手段提取断层两侧各级湖岸地貌高程信息，计算垂直位移；侧重光释光和宇宙成因核素暴露测年，确定各级湖岸地貌年龄序列；两者结合，估算湖岸地貌垂直活动速率；确认和补充前期其他地貌类型垂直运动工作，全面获取晚第四纪以来垂直活动速率的时空分布特征；结合走滑速率结果，确定垂直与水平运动分配关系；深入认识格仁错断裂与吴如错断裂、申扎正断裂系的运动学关系，分析垂直运动形成机制及其构造意义。

格仁错断裂曾被认为是青藏高原中部物质向东快速逃逸（10-20mm/yr）的南部边界断裂——喀喇昆仑-嘉黎断裂的中东段，同时其东段又与南北向申扎裂谷相接。由于高原中部野外条件差，多借助遥感影像重点研究走滑运动，格仁错断裂垂直运动及其形成机制仍不清楚。本研究通过遥感影像解译、无人机摄影测量技术、光释光等多种测年手段、精细野外构造地貌填图，获取了格仁错断裂系列湖岸阶地等断错地貌的可靠垂直运动历史，并对申扎裂谷北段晚第四纪活动速率进行初步约束。研究结果揭示格仁错断裂主段晚第四纪以来垂直速率基本稳定在0.05-0.1mm/yr，垂直与水平运动比值由北西（与吴如错断裂交汇区）2-4%向东南（与申扎裂谷交汇区）增加到5.5-9.5%；申扎裂谷北段晚第四纪以来垂直（伸展）活动速率由南部的0.5-1mm/yr向北端交汇区增加到2-4mm/yr。区域构造与地貌分析表明，格仁错-吴如错共轭走滑断裂带内物质向东运动驱动着格仁错断裂北盘相对南盘下降。格仁错断裂的右旋走滑运动导致了申扎裂谷北端加速伸展，同时申扎裂谷强化了格仁错断裂主段东南部的垂直运动。我们的结果支持青藏高原中部近东西向的共轭走滑与裂谷伸展共同协调的连续变形模式，为深入理解板块运动应力分配、造山带变形与动力学过程和地震灾害评估提供了关键数据。