Active tectonics of the Pamir Mountains: kinematics and dynamics

帕米尔山脉的活动构造：运动学和动力学

• 批准号: 2284010
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2284010
• 关键词: Active; tectonics; Pamir; Mountains; kinematics

The rules that govern the large-scale active deformation within the continents, and the ways inwhich tectonic motions are accommodated by slip on active faults during earthquakes, are first-order questions, with many of the models established from observations in the India-Eurasia collision zone. In the India/Asia collision, about 30mm/yr of convergence is distributed across a region that is several thousand kilometresin north-south extent[1 -3]. As a result, individual faultscan movevery slowly(order of <1 mm/yr) and have earthquake repeat times on the scale of thousands of years[3]. This means for most faults north of the Himalayan thrust,the timing, frequency and magnitude of past events is unknown.The seismic data record in Central Asia began in 1901[4]and has since sampled four major (>M7) earthquakes in Tajikistan, three of these in the Pamir[5]-[9]. However, geomorphic evidence of Pleistocene/Holocene ruptureselsewhereshows this record is incomplete[10]. ThePamir is alow relief plateau on the western syntaxis of the India-Eurasia collision,composed of a complex set of terranes accreted across the Mesozoic and Cenozoic[11]. It isa site of intracontinental subduction,at both its northern and southern margins [12][13],and is undergoing westward gravitational collapse into the neighbouring Tajik Basin[1].Despite the high north-south convergence velocities in GNSS data, the majority of strain happening in the Pamir appears to be east-west orientated[14][2][15].In addition, there appears to be more east-west strain in the western Pamir than the eastern Pamir[1]. The interior deformationis thought to be taken up by relatively few major faults, consisting of east-west trending thrust/strike-slip faults exploiting terrane sutures, cut bytwo north-south trending strike-slip/normal faultzones[16][17][10].This rich set of behaviours depend on external forces acting on the Pamir;gravitational forceson the topography;and the resistive forces of the faults in the brittle lithosphereand/orthe viscosity of the ductile lithosphere. They also depend on the inherited geologic structuresformed as the Pamir were built. To determine how these structures and forces drive the deformation,the deformation needs to be well characterized. This will be doneusing GNSS measurements of strain, measurements of the long-term average slip rates ofthe faults, and an understanding of their slip vectors. Studyingmajor earthquakeson these faultsgivesus the best chance of extracting their slip rates and slip vectors, and will provide information on magnitude and repeat time, pertinent to seismic hazard assessments. Since most of the major earthquakes will have occurred pre-1901, studyingrecent surface ruptures and dating offset markers (using radiocarbon or optically stimulated luminescence[18]) will be necessary, in addition to cataloginglarger scale offsets in existing geological maps.Aims and ObjectivesThe aim of this project is characterizing motion on major faults in the Pamir Plateau, and using this data to obtain insights into seismic hazard and tectonic kinematics in the region, both of which are poorly understood. I will then attempt to address why we observe this kinematic behavior, and how it depends on the region's geologic structures and forces.

在地震期间，通过在主动断层上滑倒来适应大陆内大规模主动变形的规则是一阶问题，其中许多模型从印度 - 欧洲碰撞区的观察中建立了许多模型。在印度/亚洲碰撞中，收敛的大约30mm/年分布在数千公里南北范围的地区[1-3]。结果，单个故障扫描缓慢地移动（<1 mm/yr的顺序），并且在数千年的规模上具有地震重复时间[3]。这意味着在喜马拉雅推力以北的大多数断层，过去事件的时机，频率和幅度尚不清楚。中亚的地震数据记录始于1901年[4]，此后已经对塔吉克斯坦的四个主要（> M7）地震进行了采样，其中三个在Pamir [5] - [9]中。然而，更新世/全新世破裂的地球层的地貌证据不完整[10]。 Thepamir是印度 - 欧洲抗冲突的西部语法上的浮雕高原，由中生代和新生代中积聚的一组复杂的地层组成[11]。它的近乎北部和南部边缘[12] [13]的ISA位点，正在向西重力崩溃到邻近的塔吉克盆地[1]。比东帕米尔（Easter Pamir）在西部的帕米尔（Pamir）中菌株[1]。室内变形被认为是由相对较少的主要断层所占据的，包括东西向趋势推力/上流滑动断层，利用地层缝合线，向北延伸到南北偏斜的趋势趋势滑移/正常断裂/正常断裂/正常断层[16] [17] [10] [10]。岩石圈/或延性岩石圈的粘度。它们还依赖于建造Pamir的遗传地质结构。为了确定这些结构和力如何驱动变形，需要很好地表征变形。这将是通过菌株的GNSS测量，对断层的长期平均滑动速率的测量以及对它们的滑动向量的理解。研究这些断层的地震是提取其滑动速率和滑动向量的最佳机会，并将提供有关幅度和重复时间的信息，与地震危险评估有关。 Since most of the major earthquakes will have occurred pre-1901, studyingrecent surface ruptures and dating offset markers (using radiocarbon or optically stimulated luminescence[18]) will be necessary, in addition to cataloginglarger scale offsets in existing geological maps.Aims and ObjectivesThe aim of this project is characterizing motion on major faults in the Pamir Plateau, and using this data to obtain insights into该地区的地震危害和构造运动学，这两者都鲜为人知。然后，我将尝试解决为什么我们观察这种运动学行为，以及它如何取决于该地区的地质结构和力量。