The Pamir Frontal Thrust System: Rates, Style, and Controls on Deformation

该项目的重点是位于中国最西部帕米尔高原和天山交界处的结构走廊。这两个相对的造山带逐渐相互碰撞，在它们之间，困住了该地区最大的河流克孜勒苏河。在一个空间紧凑的区域，各种各样的结构和不同的变形机制，包括低角度逆冲断层，逆断层，褶皱陡坎，褶皱和挠曲滑动断层，以适应快速收敛。帕米尔前缘冲断系统是帕米尔造山楔的前缘，在紧邻克孜勒苏河的地方，在其他地方，主断层位于距离克孜勒苏河许多公里的地方。这种沿走向的变化提供了一个机会，以评估有效的河流侵蚀可以集中变形的概念。更快的变形速率远离轴向河流将倾向于否定侵蚀变形假说。与更远的地点相比，天山南缘靠近克孜勒苏的构造的加速速率将支持侵蚀变形假说。为了确定变形率，研究小组将：利用干涉合成孔径雷达描绘十年时间尺度上的区域变形模式;利用光激发发光法确定活跃的表面断裂断层的日期;利用光激发发光法、宇宙成因放射性核素法和放射性碳法确定阶地和扇的变形日期;利用磁性地层学和（U-Th）/He测年法确定长期滑动率;主动侵蚀在调节变形中的作用仍在积极辩论中，尽管许多数值模型预测了概念上有吸引力的观点，即集中侵蚀促进局部和加速变形，但很少有明确的案例研究表明这种联系。这项研究在帕米尔天山可能提供明确的现场证据之间的联系侵蚀和变形，因为该地区有许多有利的属性，应该允许一个明确的评估模式和变形率的河流系统。除了提供对山区动态的洞察力和评估一个流行的构造地貌学范式，几个大型活动断层的古地震分析将提高对这些断层造成的地震危险的理解，其中一些断层已经产生了致命的，最近的地震。最后，该项目将涉及与中国科学家的实质性合作，为研究生和本科生提供研究机会，并与学校和博物馆进行外联。

This project focuses on the structural corridor that lies at the interface between the Pamirs and the Tian Shan in westernmost China. These two, oppositely facing orogens are progressively impinging on each other, and between them, have trapped the largest river in the region, the Kezilesu. Across a spatially compact zone, a diverse array of structures and contrasting deformation mechanisms accommodate rapid convergence, including low-angle thrust faults, reverse faults, fold scarps, folds, and flexural slip faults. Representing the leading edge of the Pamir orogenic wedge, the Pamir Frontal Thrust system is in places immediately adjacent to the Kezilesu River and at others the primary fault lies many kilometers from the river. This along-strike variability provides an opportunity to assess the concept that efficient fluvial erosion can focus deformation. Faster deformation rates farther from the axial river would tend to negate the erosion-deformation hypothesis. Accelerated rates on structures across the southern margin of the Tian Shan that are proximal to the Kezilesu compared to more distal sites would support the erosion-deformation hypothesis. To determine deformation rates, the research team will: delineate regional patterns of deformation at decadal time scales using InSAR; date active surface-rupturing faults using optically stimulated luminescence methods; date deformation of terraces and fans using optically stimulated luminescence, cosmogenic radionuclide, and radiocarbon methods; determine long term slip-rates using magnetostratigraphy and (U-Th)/He dates; and use seismic sections to constrain subsurface structure.The role of active erosion in modulating deformation is still actively debated Whereas the conceptually attractive idea that focused erosion promotes localized and accelerated deformation is predicted by many numerical models very few unequivocal case studies exist that demonstrate such a linkage. This study in the Pamir-Tian Shan may provide unequivocal field evidence for a linkage between erosion and deformation because the region has many favorable attributes that should permit a clear assessment of the pattern and rate of deformation with respect to the river system. In addition to providing insight on the dynamics of mountain belts and assessing a popular tectonic geomorphology paradigm, paleoseismic analysis of several large active faults will improve understanding of the seismic hazards posed by these faults, some of which have produced deadly, recent earthquakes. Finally, the project will involve substantial collaboration with Chinese scientists, research opportunities for graduate and undergraduate students, and outreach to schools and museums.