指導教授：陳于高臺灣大學：地質科學研究所鍾令和Chung, Ling-HoLing-HoChung2014-11-262018-06-282014-11-262018-06-282014http://ntur.lib.ntu.edu.tw//handle/246246/262005喀拉崑崙－嘉黎斷裂帶是西藏唯一大型右移走滑斷層系統，在青藏高原向東逃脫模型中扮演很重要的角色。本研究工作利用各種衛星影像，與適合第四紀相關的定年技術，進行喀拉崑崙-嘉黎斷層東段活動構造與地形學的研究。本研究工作的主要成果有二：第一，斷裂帶中段的格仁錯斷層相當活躍，依據光螢光定年結果推估，在五萬年內的滑移速率約在14.6 ± 3.1 mm/yr。而且，斷層似乎以每次約3公尺的特徵地震行為活動，依據地形證據顯示此現象至少重複發生七次以上，配合斷層速率計算格仁錯斷層大約每兩百年左右就會引發規模7.2-7.4的大地震。第二，同一系統的嘉黎斷層卻似乎不具活動性，依據定年的結果推估主斷層線的部份已有兩萬年未曾有活動的紀錄。反而是原先認為從屬於嘉黎斷層的分支斷層－那曲斷層在地形上有許多活動跡象。格仁錯斷層、那曲斷層與發生1951年規模八地震的崩錯斷層具有相近的地形特徵與斷層活動性，其所組成雁行排列右移斷層系統為目前西藏中部最活躍的構造單元，並獨立於原本的喀拉崑崙－嘉黎斷層之外。The Karakoram-Jiali fault zone (KJFZ) is the only major dextral fault system in Tibet, and plays an important role in the eastward extrusion of the Tibetan Plateau. Armijo et al. (1989) first recognized the KJFZ and proposed it as the structural boundary along which eastward movement of the Qiangtang terrane relative to the Lhasa terrane. This study focus on the activity of the eastern KJFZ, including with the Jiali fault (JF) and the Gyaring Co fault (GCF). Using high resolution satellite images, I was able to remap those two faults. Several geochronological methods are used, including radiocarbon, in-situ cosmogenic exposure, and optically stimulated luminescence (OSL). The GCF, one of the en echelon faults of the KJFZ, has been reported as a dextral fault, striking N50°-60°W. According to our OSL ages, a slip rate of the GCF can be estimated as 14.6 ± 3.1 mm/yr since ca. 50ka. This study also focuses on a section of the western segment of the GCF, where the slip has been recognized to have occurred 3.0 ± 1.6 m more than 7 times. This ~3 m slip implies Mw 7.2-7.4 earthquakes recurring to the western segment in every 200 yrs, and may reach about Mw 7.7 if both segments break at the same time. Along JF, the main Jiali fault has become less active since ca. 20ka. The field investigation shows there may have been only one small possible event during the Holocene, but none in the Late Pleistocene. The Nagqu fault (NF), previously mapped as the horsetail branch of the JF, shows many evidences to indicate that it is an active fault. The slip rate of the NF is 13~26 mm/yr, as fast as the GCF. The GCF and the NF are similar to another en echelon minor fault, named the Beng Co fault (BCF), which was located on the 1951 M8 event. Such a high slip rate suggests that the central en echelon minor faults of the original KJFZ are kinematically different from the Karakoram and Jiali faults. Turning to inactive along the main Jiali fault may be attributed to the orientation of the Jiali fault, which is parallel to the extensional axis and has no differential stress acting across it. On the other hand, the en echelon faults play essential roles in accommodating the stress in a certain tectonic system.致謝 i 中文摘要 ii ABSTRACT iii CONTENTS iv LIST OF FIGURES viii LIST OF TABLES xxi Chapter 1 Introduction 1 1.1 Tectonic environment 1 1.2 Purpose of this study 3 Chapter 2 Regional background 5 2.1 Crustal deformation models of Tibet 8 2.1.1 Argand-type underthrusting models 8 2.1.2 ‘Rigid block’ models 10 2.1.3 Continuum models 13 2.1.4 Lower crustal flow models 14 2.2 The Karakoram-Jiali Fault Zone 16 2.2.1 Karakoram Fault (喀拉崑崙斷層) 17 2.2.2 Jiali Fault (嘉黎斷層) 20 2.2.3 En echelon faults between the Karakoram and Jiali faults 22 Chapter 3 Analytical methods 23 3.1 Mapping of active fault traces 23 3.1.1 Data resources and processing 24 3.1.2 Geomorphic offset measurements 27 3.2 The Quaternary dating methods 31 3.2.1 Sampling strategy 31 3.2.2 Radiocarbon Dating (14C age) 32 3.2.3 Optical Stimulated Luminescence Dating (OSL age) 32 3.2.4 In situ Cosmogenic Exposure Dating 38 Chapter 4 The Gyaring Co fault (格仁錯斷層) 42 Abstract 43 4.1 Introduction 43 4.1.1 Tectonic setting of the Gyaring Co fault (GCF) 46 4.2 Segmentation and amount of slip along the GCF 49 4.2.1 Western segment between lakes Goman Co and Zigui Co 49 4.2.2 Western segment between Zigui Co and Gyaring Co Lakes 60 4.2.3 Site 4 Aruo: the end of western segment of the GCF 63 4.2.4 Eastern segment between Gyaring Co and Waang Co Lake 64 4.3 Summary of small scale systematic offsets 66 4.4 Discussion 69 4.4.1 Long term slip rate of the Gyaring Co fault (GCF) 69 4.4.2 Characteristic slip along the western segment of the GCF and possible moment magnitude and recurrence interval 71 4.4.3 The Relationship between the slip record and climate change 74 4.4.4 Activity of the Gyaring Co fault from the Miocene until recently and its Kinematics 75 4.5 Conclusion 76 Acknowledgements 77 Chapter 5 The Jiali Fault (嘉黎斷層) 81 Abstract 82 5.1 Introduction 82 5.2 Background 85 5.3 Geomorphologic result along the main Jiali Fault 86 5.3.1 West of Enta 88 5.3.2 Enta-Jiali township 90 5.3.3 East of Jiali 92 5.3.4 The Nagqu Fault (那曲斷層) 94 5.3.5 The Jiagong (甲崗) and Yigong (易貢) faults 101 5.4 Discussion 103 5.4.1 The activity of the Jiali fault from Miocene to recent 103 5.4.2 Neotectonic roles of the Jiali fault and its neighboring faults 104 5.5 Conclusion 107 Acknowledgements 107 Chapter 6 Discussion 108 6.1 Late Quaternary Slip of the KJFZ v.s. Models 108 6.1.1 ‘Rigid block’ model 108 6.1.2 Conjugate fault system in central Tibet 109 6.1.3 Microplate models 110 6.1.4 Continuum models and lower crustal flow model 112 6.1.5 Underthusting model 112 6.2 “Active” and “inactive” faults of the KJFZ 113 Chapter 7 Conclusions 116 References 117 Appendix I 135 Appendix II 149 Appendix III 17122252367 bytesapplication/pdf論文公開時間：2016/09/12論文使用權限：同意有償授權(權利金給回饋學校)活動斷層西藏特徵地震thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/262005/1/ntu-103-D94224009-1.pdf