【作者】 王峰；

【导师】 徐锡伟； Paul Tapponnier；

【作者基本信息】 中国地震局地质研究所 ， 构造地质学， 2002， 博士

【摘要】 1 选题依据 具有“世界屋脊”之称的青藏高原，平均海拔高度4000多米，是世界陆地上最神秘的地方，吸引了无数的探险者和科学家。其形成、演化，对中国大陆的构造格局、气候等的影响十分巨大。阿尔金断裂带作为青藏高原的北部边缘，全长1600多公里，断裂带的总体走向约为北东75°，在遥感影像上有着明显的线性特征。近年来随着对青藏高原研究的深入，阿尔金断裂带成为地学界研究的热点，国家地震局组织的阿尔金活动断裂带课题组，曾对阿尔金断裂带进行了深入详细的研究，并编写了《阿尔金活动断裂带》一书，迄今为止，此工作仍是对阿尔金断裂带所进行的最综合、最全面的研究。与此同时，其它各国的科学家也对阿尔金断裂带进行了较系统的研究。阿尔金断裂带作为青藏高原的北部边界，分隔了塔里木盆地和青藏高原两大构造单元。断裂带南北两侧的地貌形态截然不同，两侧地貌的垂直落差在局部地段超过3000m。研究这样一条大陆内部巨型走滑断裂带，对于了解青藏高原的形成与演化模式，了解青藏高原隆升过程，了解大陆内部断裂带运动学模式，了解断裂带的晚第四纪以来滑动速率及其与地震的关系，具有重要的科学意义。 本文以国家自然基金项目《阿尔金断裂中殖段第四纪非线性断裂作用的定量地貌学研究》、地震联合基金项目《阿尔金断裂带东段破裂分段性的断错地貌研究》和中法地震科技合作项目《阿尔金活动断层》为依托，在前人工作的基础上，结合大量的野外工作，对阿尔金断裂带晚第四纪以来的滑动速率和阿尔金断裂带东段地震地表破裂分段进行了研究。 2 研究方法和工作量 技术的进步不断促进科学的发展。上一个世纪后期，航空、航天等遥感技术突飞猛进的进步为地质学的研究提供了新的方法；特别是卫星遥感影像与航空照片的出现，使我们足不出户就可以观察到整个地球的每一个角落。高性能计算机的出现，使我们能在很短的时间内对大量的遥感资料进行增强处理、分析，极大的提高了我们的工作效率。如果说，以前我们对地球进行的观察是局部微观和细节性观察，那么，航卫片遥感技术的出现，则极大地拓宽了我们的视野，使我们可以从太空以另外一个视角对地球进行从宏观到微观的综合观察。 2．1 研究方法 在研究过程中，主要采用了室内航卫片计算机处理、分析与制图，野外核实、修改、补充、各种断错地貌(位移)测量、地貌面年代学样品系统采集、室内年代学样品测试和综合分析的技术路线(图1)。 1) 高精度数字化卫星遥感影像处理与断错地貌制图 根据航卫片增强影象所显示的断错地貌特征，绘制活断层迹线的几何结构，在此基础上对活断层进行地震破裂分段。利用航卫片影象资料对活断层进行地震破裂分段主要基于以下基本观察事实：大量震例表明，一次大地震仅在一条活断层的部分地段产生地表破裂，即活断层上具有分段发生地表破裂型地震的错动习性，同一段落上震级相近、位移量相近、地表破裂长度相近的地震会以规则或不规则的复发间隔不断地重复发生，造成断错地貌接近、位移量从段落中部向两端部有规律地衰减现象，一个段落累积错动最终表现出其断错地貌明显区别于具有不同错动历史过程的相邻段落。因此，利用卫星影像进行活动断层地震破裂分段时，主要依据高分辨率卫星影象显示的断错地貌差异性特征，保证同一段落断层具有相同的错断历史一年龄相近地质体或地貌面的位移量相近、被错动的最新地质体和地貌单元相同、覆盖断层迹线的地质体和地貌单元一致;不同段落地表破裂型地震的复发间隔、断错地貌类型、累积位移量等断错地貌特征必然有所不同。因此，在卫星影像上对活断层沿线断错地貌进行详细判读、解译和绘制大比例尺断错地貌图，可以辨别出具有不同地表破裂型地震复发习性和累积断错地貌特征的地震破裂段落。 2)野外实地考察、核实与断错地貌面的系统编年根据野外实地考察核实验证或修改航卫片影象解译图件，测量各种微观断错地貌面(线)和地质体的实际水平和垂直位移量，采集必要的年代样品，通过样品的实验室测试，厘定各种断错地貌面(线)和地质体的形成年龄，确定活断层不同地段不同时期地貌面(线)的累积位移量、最新断错地貌单元年龄、位移量、覆盖活断层迹线最老地貌单元年龄等反映活断层长期滑动习性的定量参数，为活断层地震破裂分段研究奠定基础。考虑到工作区气候干旱少雨，植被发育较少，又临近沙漠，黄土覆盖严重，局部地区黄土厚度上百米，结合现有测年实验室条件，在野外主要采有热释光样品和碳十四样品。热释光样品由黄土和细、粉砂两种，碳十四样品主要是碳屑。 3)各种数据与资料的综合分析修改、完善通过野外实地核实(验证)航卫片详细解译的大比例尺断错地貌图件，结合测年资料综合分析活断层整体地震破裂的分段特性，确定各段落表征其长期滑动习性的各种定量参数，特别是其最新一次地表破裂型地震发生年代、同震位移量和长期滑动速率等参数。 4)活断层水平滑动速率的计算主要采用野外测量活断层两侧河流阶地和洪积扇的微观断错地貌确定活断层的水平或垂直位移量，很少或基本没有采用水系扭动量作为更多还原

【Abstract】 The Tibetan Plateau is the most mysterious highland on continents in the world. Its average elevation reaches 4000m and it attracts numerous explorers and scientists. The process of formation and evolution of the Tibet Plateau influence the tectonic patterns and climate of China continent greatly. The Altyn Tagh fault Zone, as the northern boundary of the Tibetan Plateau, winds more than 1500km from Lazhulong in Tibet province to Kuantanshan in Gansu province. Its linear character is conspicuous on satellite images and topographic maps with a strike of N75癊. In recent years, accompanying further studies on the Tibetan Plateau, the Altyn Tagh fault zone becomes a pop topic of geoscientific research. Ten years ago, China Seismological Bureau organized a group who worked on the Altyn Tagh fault, finished a detailed study on the large fault and compiled a book named " The Active Altyn Tagh Fault Zone". Even by now, this work is one of the most systematic works on active tectonics on the fault. Meanwhile, scientists from other countries are working on the fault zone diligently. As the northern boundary of the Tibetan Plateau, the Altyn Tagh fault separates two tectonic units: the Tarim basin and the Tibetan Plateau. The geomorphology features north to the fault and south to the fault are totally different and the elevation difference reaches 3000m. To study such a long fault zone is of great importance to know the formation and evolution of the Tibetan Plateau and its contribution to the uplift of the Tibetan Plateau and underthrusting of the India Plate.This thesis is focused on slip-rates of the Altyn Tagh fault and the segmentation features on its eastern part. The specific items are:1, the surface rupture segmentation on the eastern part of the Altyn Tagh fault and its seismological features,2, the sinistral slip-rate of the whole Altyn Tagh fault,3, the contribution of strike-slip on the Altyn Tagh fault in assimilating the underthrusting of India Plate beneath Euro-Asia Plate,4, the relationship between strike-slip on the Altyn Tagh fault and vertical and horizontal movement of the Northern Qilianshan thrust.With the progress of technology, new methods come forth continuously and furnish new ways for scientific research. In the last century, tremendous progresses in chronology, remote-sensing, computer and astronomy allow us to study geology with new methods. With satellite images and aerial photos we can observe any place on the Earth without stepping out our office. With help of fast computers, numerous satellite images can be analyzed in short time. All of these technologies improve our efficiency of working greatly.During the process of research, the following methods were adapted.First, by analyzing the TM and Spot images on the fault in detail, the surface ruptures of the fault and geometrical relationship between different parts of the Altyn Tagh fault are found. After that, mapping the terraces of rivers across the fault and alluvial fans near the fault, by this, offset features of different geological bodies near the fault and segmentation of the fault are analyzed. Then the sites, where chronological samples for dating are gathered, are determined.Secondly, by field investigating, chronological samples are collected and the indoor analysis results are corrected. By dating the samples collected in the fieldwork, ages of offset terraces or alluvial fans are obtained. According to offset features and ages of the terraces and fans, segmentation the fault is determined and its strike-slip rate is calculated.Because of drought climate and scarcity of plant in the study region, it is hard to find carbons in the region. Regarding the condition of chronology laboratory in our institute and the possible ages of the samples, thermo-luminescent dating method is adapted.To calculate the strike-slip rate on a fault, two variables are indispensable. One is displacement and the other is the age of the displacement. To get the slip-rate accurately, only offset of terraces and alluvial fans is u更多还原